Proper Radiator Cap Pressure Rating for 1994 Honda Accord EX?

[Gary Kaucher]

1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am wondering if it may have been accidentally replaced last summer.

Thanks,

Gary

 

[jim beam]

1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am wondering if it may have been accidentally replaced last summer.

Thanks,

Gary

before worrying about the cap pressure, consider the following:

when was the thermostat last replaced?

in what condition is the radiator? is it clogged/sludged? filled with bugs?

what level is the coolant? are you losing any? any bubbles in it? [check inside the radiator, not just look at the expansion bottle.]

 

[Gary Kaucher]

1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am wondering if it may have been accidentally replaced last summer.

Thanks,

Gary

before worrying about the cap pressure, consider the following:

when was the thermostat last replaced?

in what condition is the radiator? is it clogged/sludged? filled with bugs?

what level is the coolant? are you losing any? any bubbles in it? [check inside the radiator, not just look at the expansion bottle.]

The thermostat was replaced last summer. When I looked into the radiator recently I did not see anything particulary unsightly, but I suspect that it may have been six years and 50K since the antifreeze has been changed. I keep the coolant level between Cold and Hot, and I don't appear to be losing any. I thought that I saw bubbles once in the expansion bottle, so I fiddled with the radiator cap, and they seemed to go away. I imagine that I could be due for some kind of radiator flush and antifreeze replacement. The antifreeze doesn't look too bad, but I suspect I've seen cleaner.

I called an auto parts place just to see what pressure rating was listed for my Honda Accord's radiator cap and they said 16 psi. Since the one that I have is 13 psi I wonder if it is the wrong radiator cap, and if it would make a significant difference in the ECT sensor's ability to turn the fans on at the correct temperature.

Or, is six year old antifreeze more likely to be a factor?

Thanks,
Gary

 

[Nick (archive)]

The temperature level should not go above the 1/4 mark on he 94-97 models. On my 95 Accord in the 9 years that I have owned it never went past that mark. You could have some air in the system. I would suggest that you purge that air out first and go from there. I'm not certain if the cap could be a problem but just to rule out any possibilities, I'd get one from your local Honda dealer. They shouldn't be that expensive to get and it's one thing to rule out of the checklist.

Good Luck,
Nick

1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am wondering if it may have been accidentally replaced last summer.

Thanks,

Gary

before worrying about the cap pressure, consider the following:

when was the thermostat last replaced?

in what condition is the radiator? is it clogged/sludged? filled with bugs?

what level is the coolant? are you losing any? any bubbles in it? [check inside the radiator, not just look at the expansion bottle.]

The thermostat was replaced last summer. When I looked into the radiator recently I did not see anything particulary unsightly, but I suspect that it may have been six years and 50K since the antifreeze has been changed. I keep the coolant level between Cold and Hot, and I don't appear to be losing any. I thought that I saw bubbles once in the expansion bottle, so I fiddled with the radiator cap, and they seemed to go away. I imagine that I could be due for some kind of radiator flush and antifreeze replacement. The antifreeze doesn't look too bad, but I suspect I've seen cleaner.

I called an auto parts place just to see what pressure rating was listed for my Honda Accord's radiator cap and they said 16 psi. Since the one that I have is 13 psi I wonder if it is the wrong radiator cap, and if it would make a significant difference in the ECT sensor's ability to turn the fans on at the correct temperature.

Or, is six year old antifreeze more likely to be a factor?

Thanks,
Gary

 

[jim beam]

1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am wondering if it may have been accidentally replaced last summer.

Thanks,

Gary

before worrying about the cap pressure, consider the following:

when was the thermostat last replaced?

in what condition is the radiator? is it clogged/sludged? filled with bugs?

what level is the coolant? are you losing any? any bubbles in it? [check inside the radiator, not just look at the expansion bottle.]

The thermostat was replaced last summer. When I looked into the radiator recently I did not see anything particulary unsightly, but I suspect that it may have been six years and 50K since the antifreeze has been changed.

hard to change the thermostat without changing the coolant.

I keep the coolant level between Cold and Hot, and
I don't appear to be losing any. I thought that I saw bubbles once in the expansion bottle, so I fiddled with the radiator cap, and they seemed to go away.

hmm, that's suspect.

I imagine that I could be due for some kind of radiator flush and antifreeze replacement. The antifreeze doesn't look too bad, but I suspect I've seen cleaner.

can't hurt.

I called an auto parts place just to see what pressure rating was listed for my Honda Accord's radiator cap and they said 16 psi. Since the one that I have is 13 psi I wonder if it is the wrong radiator cap, and if it would make a significant difference in the ECT sensor's ability to turn the fans on at the correct temperature.

no, it won't affect that at all. a higher pressure cap just elevates the boiling point a little.

Or, is six year old antifreeze more likely to be a factor?

not unless it's really dirty. check the thermal switch and the fan relays for operation. if the switch checks out ok, to eliminate the head gasket as a suspect, have a chemical test done on the coolant to see if there's exhaust gas in there. then look at the radiator again. they fill up with bugs and all kinds of other debris that impairs airflow significantly. if replacement is in order, i've had good experience with these folks:

http://catalog.eautopartscatalog.com/ipb/wizard.jsp?partner=ipb&clientid=alleurasianautoparts&baseurl=http://www.alleurasianautoparts.com/&cookieid=1TU0Y4A0K1US16U12G&year=1994&make=HO&model=ACC-EX2-002&category=G&part=Radiator&appTransmissionType=Automatic

i'd go plastic tank.

 

[AZ Nomad]

Gary Kaucher wrote:
1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am wondering if it may have been accidentally replaced last summer.

Thanks,

Gary

before worrying about the cap pressure, consider the following:

when was the thermostat last replaced?

in what condition is the radiator? is it clogged/sludged? filled with bugs?

what level is the coolant? are you losing any? any bubbles in it? [check inside the radiator, not just look at the expansion bottle.]

The thermostat was replaced last summer. When I looked into the radiator recently I did not see anything particulary unsightly, but I suspect that it may have been six years and 50K since the antifreeze has been changed.

hard to change the thermostat without changing the coolant.

Only if you do the job with the car upside down.

 

[jim beam]

Gary Kaucher wrote:
1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am wondering if it may have been accidentally replaced last summer.

Thanks,

Gary

before worrying about the cap pressure, consider the following:

when was the thermostat last replaced?

in what condition is the radiator? is it clogged/sludged? filled with bugs?

what level is the coolant? are you losing any? any bubbles in it? [check inside the radiator, not just look at the expansion bottle.]

The thermostat was replaced last summer. When I looked into the radiator recently I did not see anything particulary unsightly, but I suspect that it may have been six years and 50K since the antifreeze has been changed.

hard to change the thermostat without changing the coolant.

Only if you do the job with the car upside down.

ok, let's be pedantic because you know i'm like that. the elevation of the thermostat relative to the engine block is about 2/3rds the height of the whole. and of that, the head carries a significant quantity of the coolant. for the engine, i therefore estimate you'll lose roughly 1/2 its fill of coolant. for the radiator, i estimate roughly 1/3rd. hoses, maybe another 1/3rd. that makes roughly 40% of the coolant changes with a thermostat. that's a higher percentage than you can change on the automatic transmission.

 

[Gary Kaucher]

Gary Kaucher wrote:
1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am

wondering
if

it
may have been accidentally replaced last summer.

Thanks,

Gary

before worrying about the cap pressure, consider the following:

when was the thermostat last replaced?

in what condition is the radiator? is it clogged/sludged? filled with bugs?

what level is the coolant? are you losing any? any bubbles in it? [check inside the radiator, not just look at the expansion bottle.]

The thermostat was replaced last summer. When I looked into the radiator recently I did not see anything particulary unsightly, but I suspect that it may have been six years and 50K since the antifreeze has been changed.

hard to change the thermostat without changing the coolant.

I keep the coolant level between Cold and Hot, and
I don't appear to be losing any. I thought that I saw bubbles once in the expansion bottle, so I fiddled with the radiator cap, and they seemed to go away.

hmm, that's suspect.

I imagine that I could be due for some kind of radiator flush and antifreeze replacement. The antifreeze doesn't look too bad, but I suspect I've seen cleaner.

can't hurt.

I called an auto parts place just to see what pressure rating was listed for my Honda Accord's radiator cap and they said 16 psi. Since the one that I have is 13 psi I wonder if it is the wrong radiator cap, and if it would make a significant difference in the ECT sensor's ability to turn the fans on at the correct temperature.

no, it won't affect that at all. a higher pressure cap just elevates the boiling point a little.

Or, is six year old antifreeze more likely to be a factor?

not unless it's really dirty. check the thermal switch and the fan relays for operation. if the switch checks out ok, to eliminate the head gasket as a suspect, have a chemical test done on the coolant to see if there's exhaust gas in there. then look at the radiator again. they fill up with bugs and all kinds of other debris that impairs airflow significantly. if replacement is in order, i've had good experience with these folks:

http://catalog.eautopartscatalog.com/ipb/wizard.jsp?partner=ipb&clientid=alleurasianautoparts&baseurl=http://www.alleurasianautoparts.com/&cookieid=1TU0Y4A0K1US16U12G&year=1994&make=HO&model=ACC-EX2-002&category=G&part=Radiator&appTransmissionType=Automatic

i'd go plastic tank.

This car is mostly driven on short trips over country roads. It is only recently that we are having really hot weather here in PA, so I suspect that this problem may have existed for awhile, possibly since last summer. Yesterday was particularly hot, and I drove the car for about an hour before I noticed that the fans were cycling at a higher than expected temperature (around the 3/4 mark). Overnight things cooled off, and when I checked the antifreeze reservoir, it looked like the radiator may have sipped about a pint out of it. I removed the radiator cap, started up the engine and added antifreeze whenever I could. I would say that it may have taken another pint . Now the fans are back to cycling on and off at about the 1/4 mark as Nick indicated. So I think that might be back in business. I did notice some things when I purged the radiator:

1) I would sometimes see bubbles coming from the coolant at the radiator fill.
2) The level of coolant would go up and sometimes overflow the radiator when I revved the engine up to about 2000 RPM.

Do either of these things imply a bad head gasket? If so, maybe that is the reason that I needed to add coolant. If not, maybe the radiator was never properly purged last summer when the thermostat was changed.

How can you tell when the thermostat opens? Does the big hose on top of the radiator become pressurized?

Thanks everyone for all the help.

Gary

 

[jim beam]

Gary Kaucher wrote:
1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am wondering if it may have been accidentally replaced last summer.

Thanks,

Gary

before worrying about the cap pressure, consider the following:

when was the thermostat last replaced?

in what condition is the radiator? is it clogged/sludged? filled with bugs?

what level is the coolant? are you losing any? any bubbles in it? [check inside the radiator, not just look at the expansion bottle.]

The thermostat was replaced last summer. When I looked into the radiator recently I did not see anything particulary unsightly, but I suspect that it may have been six years and 50K since the antifreeze has been changed.

hard to change the thermostat without changing the coolant.

I keep the coolant level between Cold and Hot, and
I don't appear to be losing any. I thought that I saw bubbles once in the expansion bottle, so I fiddled with the radiator cap, and they seemed to go away.

hmm, that's suspect.

I imagine that I could be due for some kind of radiator flush and antifreeze replacement. The antifreeze doesn't look too bad, but I suspect I've seen cleaner.

can't hurt.

I called an auto parts place just to see what pressure rating was listed for my Honda Accord's radiator cap and they said 16 psi. Since the one that I have is 13 psi I wonder if it is the wrong radiator cap, and if it would make a significant difference in the ECT sensor's ability to turn the fans on at the correct temperature.

no, it won't affect that at all. a higher pressure cap just elevates the boiling point a little.

Or, is six year old antifreeze more likely to be a factor?

not unless it's really dirty. check the thermal switch and the fan relays for operation. if the switch checks out ok, to eliminate the head gasket as a suspect, have a chemical test done on the coolant to see if there's exhaust gas in there. then look at the radiator again. they fill up with bugs and all kinds of other debris that impairs airflow significantly. if replacement is in order, i've had good experience with these folks:

http://catalog.eautopartscatalog.com/ipb/wizard.jsp?partner=ipb&clientid=alleurasianautoparts&baseurl=http://www.alleurasianautoparts.com/&cookieid=1TU0Y4A0K1US16U12G&year=1994&make=HO&model=ACC-EX2-002&category=G&part=Radiator&appTransmissionType=Automatic i'd go plastic tank.

This car is mostly driven on short trips over country roads. It is only recently that we are having really hot weather here in PA, so I suspect that this problem may have existed for awhile, possibly since last summer. Yesterday was particularly hot, and I drove the car for about an hour before I noticed that the fans were cycling at a higher than expected temperature (around the 3/4 mark). Overnight things cooled off, and when I checked the antifreeze reservoir, it looked like the radiator may have sipped about a pint out of it. I removed the radiator cap, started up the engine and added antifreeze whenever I could. I would say that it may have taken another pint . Now the fans are back to cycling on and off at about the 1/4 mark as Nick indicated.

excellent. you'll see gas mileage improve now too!

So I think
that might be back
in business. I did notice some things when I purged the radiator:

1) I would sometimes see bubbles coming from the coolant at the radiator fill.

that's normal when refilling. fill it as much as you can, then put the cap back on and crack open the bleed nipple. let some air out, close, rev the engine, and crack open the nipple one more time. bubbles you see after a few minutes and at full working temperature are suspect. keep the heater full on while doing this too.

2) The level of coolant would go up and sometimes overflow the radiator when I revved the engine up to about 2000 RPM.

that's normal - don't worry about it. the fluid expands as it gets warm and will surge as the pump increases pressure.

Do either of these things imply a bad head gasket?
no.

If so, maybe that is the
reason that I needed to
add coolant. If not, maybe the radiator was never properly purged last summer when the thermostat was changed.

let's say the system was never purged. replenish accordingly, but stay on top of this situation by checking daily. the early stages of a gasket failure have very minor symptoms and may persist for a considerable period before they get bad enough to warrant surgery.

How can you tell when the thermostat opens? Does the big hose on top of the radiator become pressurized?

there will be pressure, but that's not a result of the thermostat function - pressure is equal throughout the system. the thermostat's open when the /bottom/ hose gets hot.

 

[Elle]

Gary Kaucher wrote:
Gary Kaucher wrote:
1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and
now both my AC fan
and Radiator fan seem to be capable of turning on and
off. However,
I don't think that they are turning on soon enough.
With the recent hot
weather here in PA, if I idle the car with the AC
off, I've noticed that
the temperature gauge needle will rise to just under
the red zone (hot),
and then both fans (AC and Radiator) will come on,
cool things a
little, turn off and then cycle on and off as they
should, but at a
generally
higher temperature than I remember in the past. The
radiator cap is
rated at
13 psi. Is this the correct rating for the above
vehicle? I am wondering
if
it
may have been accidentally replaced last summer.

Thanks,

Gary

before worrying about the cap pressure, consider the
following:

when was the thermostat last replaced?

in what condition is the radiator? is it
clogged/sludged? filled with
bugs?

what level is the coolant? are you losing any? any
bubbles in it?
[check inside the radiator, not just look at the
expansion bottle.]

The thermostat was replaced last summer. When I looked
into the
radiator recently I did not see anything particulary
unsightly, but I
suspect that it may have been six years and 50K since
the antifreeze
has been changed.

hard to change the thermostat without changing the
coolant.

Only if you do the job with the car upside down.

ok, let's be pedantic because you know i'm like that.

I don't know what I'd call you, except it's not "pedantic." Let's just be honest.

One does not have to change the coolant on all Hondas after a thermostat change.

Have a gallon of coolant (OEM or whatever is used in the car) on hand, because one certainly will lose some.

the elevation of the thermostat relative to the engine
block is about 2/3rds the height of the whole. and of
that, the head carries a significant quantity of the
coolant. for the engine, i therefore estimate you'll lose roughly 1/2 its fill of coolant. for the radiator, i estimate roughly 1/3rd. hoses, maybe another 1/3rd. that makes roughly 40% of the coolant changes with a thermostat. that's a higher percentage than you can change on the automatic transmission.

That's the ball park.

 

[Gary Kaucher]

Gary Kaucher wrote:
Gary Kaucher wrote:
1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am wondering if it may have been accidentally replaced last summer.

Thanks,

Gary

before worrying about the cap pressure, consider the following:

when was the thermostat last replaced?

in what condition is the radiator? is it clogged/sludged? filled with bugs?

what level is the coolant? are you losing any? any bubbles in it? [check inside the radiator, not just look at the expansion bottle.]

The thermostat was replaced last summer. When I looked into the radiator recently I did not see anything particulary unsightly, but I suspect that it may have been six years and 50K since the antifreeze has been changed. hard to change the thermostat without changing the coolant.

I keep the coolant level between Cold and Hot, and
I don't appear to be losing any. I thought that I saw bubbles once in the expansion bottle, so I fiddled with the radiator cap, and they seemed to go away.
hmm, that's suspect.

I imagine that I could be due for some kind of radiator flush and antifreeze replacement. The antifreeze doesn't look too bad, but I suspect I've seen cleaner.
can't hurt.

I called an auto parts place just to see what pressure rating was

listed
for

my Honda Accord's radiator cap and they said 16 psi. Since the one that I have is 13 psi I wonder if it is the wrong radiator cap, and if it would make a significant difference in the ECT sensor's ability to turn the fans on at the correct temperature. no, it won't affect that at all. a higher pressure cap just elevates the boiling point a little.

Or, is six year old antifreeze more likely to be a factor? not unless it's really dirty. check the thermal switch and the fan relays for operation. if the switch checks out ok, to eliminate the head gasket as a suspect, have a chemical test done on the coolant to see if there's exhaust gas in there. then look at the radiator again. they fill up with bugs and all kinds of other debris that impairs airflow significantly. if replacement is in order, i've had good experience with these folks:

http://catalog.eautopartscatalog.com/ipb/wizard.jsp?partner=ipb&clientid=alleurasianautoparts&baseurl=http://www.alleurasianautoparts.com/&cookieid=1TU0Y4A0K1US16U12G&year=1994&make=HO&model=ACC-EX2-002&category=G&part=Radiator&appTransmissionType=Automatic

i'd go plastic tank.

This car is mostly driven on short trips over country roads. It is only recently that we are having really hot weather here in PA, so I suspect that this problem may have existed for awhile, possibly since last summer. Yesterday was particularly hot, and I drove the car for about an hour before I noticed that the fans were cycling at a higher than expected temperature (around the 3/4 mark). Overnight things cooled off, and when I checked the antifreeze reservoir, it looked like the radiator may have sipped about a pint out of it. I removed the radiator cap, started up the engine and added antifreeze whenever I could. I would say that it may have taken another pint . Now the fans are back to cycling on and off at about the 1/4 mark as Nick indicated.

excellent. you'll see gas mileage improve now too!

So I think
that might be back
in business. I did notice some things when I purged the radiator:

1) I would sometimes see bubbles coming from the coolant at the radiator fill.

that's normal when refilling. fill it as much as you can, then put the cap back on and crack open the bleed nipple. let some air out, close, rev the engine, and crack open the nipple one more time. bubbles you see after a few minutes and at full working temperature are suspect. keep the heater full on while doing this too.

2) The level of coolant would go up and sometimes overflow the radiator when I revved the engine up to about 2000 RPM.

that's normal - don't worry about it. the fluid expands as it gets warm and will surge as the pump increases pressure.

Do either of these things imply a bad head gasket?
no.

If so, maybe that is the
reason that I needed to
add coolant. If not, maybe the radiator was never properly purged last summer when the thermostat was changed.

let's say the system was never purged. replenish accordingly, but stay on top of this situation by checking daily. the early stages of a gasket failure have very minor symptoms and may persist for a considerable period before they get bad enough to warrant surgery.

How can you tell when the thermostat opens? Does the big hose on top of the radiator become pressurized?

there will be pressure, but that's not a result of the thermostat function - pressure is equal throughout the system. the thermostat's open when the /bottom/ hose gets hot.

Thanks everyone for all the help.

Gary

Where is the bleed nipple on the radiator. Is it possible that some radiators don't have one. Or are some radiator caps equipped with a bleed nipple?

Thanks,
Gary

 

[jim beam]

Gary Kaucher wrote:
Gary Kaucher wrote:
1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am wondering if it may have been accidentally replaced last summer.

Thanks,

Gary

before worrying about the cap pressure, consider the following:

when was the thermostat last replaced?

in what condition is the radiator? is it clogged/sludged? filled with bugs?

what level is the coolant? are you losing any? any bubbles in it? [check inside the radiator, not just look at the expansion bottle.] The thermostat was replaced last summer. When I looked into the radiator recently I did not see anything particulary unsightly, but I suspect that it may have been six years and 50K since the antifreeze has been changed. hard to change the thermostat without changing the coolant.

I keep the coolant level between Cold and Hot, and
I don't appear to be losing any. I thought that I saw bubbles once in the expansion bottle, so I fiddled with the radiator cap, and they seemed to go away.
hmm, that's suspect.

I imagine that I could be due for some kind of radiator flush and antifreeze replacement. The antifreeze doesn't look too bad, but I suspect I've seen cleaner.
can't hurt.

I called an auto parts place just to see what pressure rating was listed for my Honda Accord's radiator cap and they said 16 psi. Since the one that I have is 13 psi I wonder if it is the wrong radiator cap, and if it would make a significant difference in the ECT sensor's ability to turn the fans on at the correct temperature. no, it won't affect that at all. a higher pressure cap just elevates the boiling point a little.

Or, is six year old antifreeze more likely to be a factor? not unless it's really dirty. check the thermal switch and the fan relays for operation. if the switch checks out ok, to eliminate the head gasket as a suspect, have a chemical test done on the coolant to see if there's exhaust gas in there. then look at the radiator again. they fill up with bugs and all kinds of other debris that impairs airflow significantly. if replacement is in order, i've had good experience with these folks:

http://catalog.eautopartscatalog.com/ipb/wizard.jsp?partner=ipb&clientid=alleurasianautoparts&baseurl=http://www.alleurasianautoparts.com/&cookieid=1TU0Y4A0K1US16U12G&year=1994&make=HO&model=ACC-EX2-002&category=G&part=Radiator&appTransmissionType=Automatic i'd go plastic tank.

This car is mostly driven on short trips over country roads. It is only recently that we are having really hot weather here in PA, so I suspect that this problem may have existed for awhile, possibly since last summer. Yesterday was particularly hot, and I drove the car for about an hour before I noticed that the fans were cycling at a higher than expected temperature (around the 3/4 mark). Overnight things cooled off, and when I checked the antifreeze reservoir, it looked like the radiator may have sipped about a pint out of it. I removed the radiator cap, started up the engine and added antifreeze whenever I could. I would say that it may have taken another pint . Now the fans are back to cycling on and off at about the 1/4 mark as Nick indicated.

excellent. you'll see gas mileage improve now too!

So I think
that might be back
in business. I did notice some things when I purged the radiator:

1) I would sometimes see bubbles coming from the coolant at the radiator fill.

that's normal when refilling. fill it as much as you can, then put the cap back on and crack open the bleed nipple. let some air out, close, rev the engine, and crack open the nipple one more time. bubbles you see after a few minutes and at full working temperature are suspect. keep the heater full on while doing this too.

2) The level of coolant would go up and sometimes overflow the radiator when I revved the engine up to about 2000 RPM.

that's normal - don't worry about it. the fluid expands as it gets warm and will surge as the pump increases pressure.

Do either of these things imply a bad head gasket? no.

If so, maybe that is the
reason that I needed to
add coolant. If not, maybe the radiator was never properly purged last summer when the thermostat was changed.

let's say the system was never purged. replenish accordingly, but stay on top of this situation by checking daily. the early stages of a gasket failure have very minor symptoms and may persist for a considerable period before they get bad enough to warrant surgery.

How can you tell when the thermostat opens? Does the big hose on top of the radiator become pressurized?

there will be pressure, but that's not a result of the thermostat function - pressure is equal throughout the system. the thermostat's open when the /bottom/ hose gets hot.

Thanks everyone for all the help.

Gary

Where is the bleed nipple on the radiator. Is it possible that some radiators don't have one. Or are some radiator caps equipped with a bleed nipple?

Thanks,
Gary

it's not on the radiator - it's on the aluminum engine casting where one of the big radiator hoses connect.

 

[TeGGeR®]

1994 Honda Accord EX, 4 door
4 cylinder, Automatic Transmission

I just recently replaced the Radiator fan motor, and now both my AC fan and Radiator fan seem to be capable of turning on and off. However, I don't think that they are turning on soon enough. With the recent hot weather here in PA, if I idle the car with the AC off, I've noticed that the temperature gauge needle will rise to just under the red zone (hot), and then both fans (AC and Radiator) will come on, cool things a little, turn off and then cycle on and off as they should, but at a generally higher temperature than I remember in the past. The radiator cap is rated at 13 psi. Is this the correct rating for the above vehicle? I am wondering if it may have been accidentally replaced last summer.

Check the thermostat rating. You should be using a DEALER thermostat, with a rating of 78C. A 90C (190F) thermostat will cause overheating.

Also, your rad cap should be stamped "1.1" bar, or about 16lbs. A 13lb cap is stamped "0.9".

 

[Gary Kaucher]

Check the thermostat rating. You should be using a DEALER thermostat, with a rating of 78C. A 90C (190F) thermostat will cause overheating.

Also, your rad cap should be stamped "1.1" bar, or about 16lbs. A 13lb cap is stamped "0.9".

The thermostat was replaced last summer. Hopefully, the mechanic used the correct one. Recent purging of the system seems to have helped, but I suspect that something is still wrong, and that I should change the radiator cap. The actual installed radiator cap is stamped "13lb" and "0.9", so it appears to be the wrong one. Does this mean that the coolant would be inclined to boil prematurely, and if so, what effect would that have? Would boiling coolant impair the ability of the temperature gauge sensor and ECT sensor to sense the proper temperature and respond properly? Would boiling coolant effect the tarnsfer of heat from the block to the coolant?

Is there any reason why one would intentionally install a radiator cap with a 13lb rating instead of 16lb? A car with 300K is certainly a candidate for a blown head gasket. Would installing a lower pressure rated 13lb radiator cap instead of a 16lb cap be a good way to keep coolant from being blown out the exhaust pipe?

Thanks,

Gary

 

[TeGGeR®]

The thermostat was replaced last summer. Hopefully, the mechanic used the correct one. Recent purging of the system seems to have helped, but I suspect that something is still wrong, and that I should change the radiator cap. The actual installed radiator cap is stamped "13lb" and "0.9", so it appears to be the wrong one. Does this mean that the coolant would be inclined to boil prematurely, and if so, what effect would that have?

It's possible. Change the cap with new OEM, top up the rad and see what happens. The critical thing is that the reservoir level should rise with a hot engine, but then go back down to its usual cold level when cold again. If it does not, the water is being displaced with air. By the way, this can also happen if the fluid connection between reservoir and rad filler neck is compromised. If there is a leak in that circuit, the engine will be unable to suck coolant back into the rad as it cools.

At this point, reading this thread through, I'm suspecting a failed head gasket. Your low coolant level, bubbles in the reservoir, overheating at idle...bad signs. You need to investigate that possibility if s new OEM rad cap doesn't help.

Is there any reason why one would intentionally install a radiator cap with a 13lb rating instead of 16lb?

Mistake. But their operating ranges overlap, so this should not be a disaster. A blown head gasket will cause more problems than the wrong cap.

A car with 300K is certainly a candidate for a blown head gasket.

You bet. Get a"pressure test" (NOT a "compression test") done. Some garages can do a chemical test for combustion gases in the coolant, which is probably better.

Would installing a
lower pressure rated 13lb radiator cap instead of a 16lb cap be a good way to keep coolant from being blown out the exhaust pipe?

In your case, probably not. I'd replace the cap and top up the coolant in the rad. If that doesn't work, get the head gasket checked as above.

 

[Gary Kaucher]

Check the thermostat rating. You should be using a DEALER thermostat, with a rating of 78C. A 90C (190F) thermostat will cause overheating.

I installed a cap. It was not a dealer cap, but it looks just like one. My radiator is probably an aftermarket one. I know the radiator fan is NipponDenzo, and I think the radiator is also. There is no writing on the radiator to identify it. I've seen the Toyo radiator cap, and I don't think it would work on my radiator, so I think that the "NipponDenzo type" cap is the correct cap.

At this time, the reservoir level increases when the engine heats up, but still stays at that elevated level when the engine cools down. The radiator and AC fans cycle on and off properly, and the temperature gauge stays steady about 1/4 of the way up from C (Cold). If I open up the radiator cap in the morning when it is cool, I usually have to add about 2 or 3 cups of coolant. There are no more bubbles in the coolant, and there are no coolant leaks anywhere on the ground under the car or on the engine or radiator. No unusual exhaust, and the oil looks normal.

Either I am still purging the system of air or I am in the early stages of a head gasket problem. The thermostat was replaced last summer. If it was mistakenly replaced with the 90C instead of the 78C, then my engine block could be 12C higher than it should be. Would this put undo strain on the head gasket? If it turns out to be a headgasket problem, would it be wise to use the 13lb radiator cap instead of the 16lb?

Thanks

 

[TeGGeR®]

At this time, the reservoir level increases when the engine heats up, but still stays at that elevated level when the engine cools down.

Bad, bad, bad sign. Very bad.

Check this though: The line running from rad filler neck to the bottom of the expansion reservoir tube. If it has been breached in *any* way, the engine will not be able to suck in fluid as it cools, but will suck air instead. The connection must be *absolutely* airtight.

The radiator and AC fans
cycle on and off properly,
and the temperature gauge stays steady about 1/4 of the way up from C (Cold). If I open up the radiator cap in the morning when it is cool, I usually have to add about 2 or 3 cups of coolant. There are no more bubbles in the coolant, and there are no coolant leaks anywhere on the ground under the car or on the engine or radiator. No unusual exhaust, and the oil looks normal.

Either I am still purging the system of air or I am in the early stages of a head gasket problem.

I vote for the second one (if the expansion hose is OK). Better get it looked at. Failure to quickly address a possible failed head gasket will result in a greatly increased chance of making the engine uneconomic to repair.

Make haste to a garage. Don't fool around with rad caps any more.

 

[Gary Kaucher]

Bad, bad, bad sign. Very bad.

Check this though: The line running from rad filler neck to the bottom of the expansion reservoir tube. If it has been breached in *any* way, the engine will not be able to suck in fluid as it cools, but will suck air instead. The connection must be *absolutely* airtight.

I checked this line throughly and, unfortunately, it has no problems. I guess I have some kind of gasket problem.

I did find out from my mechanic that he installed the 90C thermostat, and not the OEM 78C one. I wonder if that might have some effect on this condition. When I shut the engine off and it cools down, the thermostat closes at 90C instead of 78C. If I changed the thermostat to the OEM 78C one, would the engine somehow have an improved opportunity to draw coolant from the reservoir? Would the thermostat being open for that additional 12C differential create more suction from the reservoir as opposed to through the head gasket? Does that make any sense or is it just "wishful thinking"?

Thanks again

 

[TeGGeR®]

I did find out from my mechanic that he installed the 90C thermostat, and not the OEM 78C one.

Oh, that changes everything!

I did mention to check that, a few posts ago.

I wonder if that might have some effect on this
condition. When I shut the engine off and it cools down, the thermostat closes at 90C instead of 78C.

You have it sort of backwards. It *begins to open* at 90C, which is WELL above the proper temperature for that motor.

A 90C thermostat will cause the car to overheat. Your mechanic has committed a serious mistake here.

If I changed the thermostat to the OEM 78C one, would the engine somehow have an improved opportunity to draw coolant from the reservoir? Would the thermostat being open for that additional 12C differential create more suction from the reservoir as opposed to through the head gasket? Does that make any sense or is it just "wishful thinking"?

Replacing the thermostat is certainly worth a try.

If the fluid boils so as to cause the top of the rad to be filled with gas and not fluid, the engine will be unable to pull fluid from the reservoir back into the rad.

Put the proper **DEALER** thermostat in and see what happens.

 

[jim beam]

Oh, that changes everything!

I did mention to check that, a few posts ago.

You have it sort of backwards. It *begins to open* at 90C, which is WELL above the proper temperature for that motor.

A 90C thermostat will cause the car to overheat. Your mechanic has committed a serious mistake here.

Replacing the thermostat is certainly worth a try.

If the fluid boils so as to cause the top of the rad to be filled with gas and not fluid, the engine will be unable to pull fluid from the reservoir back into the rad.

Put the proper **DEALER** thermostat in and see what happens.

what tegger said.

wrong thermostat is not good. consider a different mechanic in the future.