99 Honda Accord temp gauge question

99 Accord 4cyl, auto, 105k miles. Had the rubber band changed a couple
months ago, shortly before the weather got cold. Also did water pump at
the same time (since they had it apart anyway), and changed plugs,
wires, etc.

Since then, at cold start, the temp needle takes forever getting off the
peg. At highway speed, it drops down to just above the peg, and only
shows in what I consider the 'normal' range (1/3 to 1/2 of scale) when
driving in town in stop and go traffic. Engine seems to run fine, and
MPG is still mid-20s in town, and a hair under 30 on highway.

Do I have a problem? If I take it back to same shop, what do I need to
ask them to check? Bad sensor? Bad gauge? Wrong T-stat?

Any ideas appreciated- I haven't done any wrenching to speak of since
carburetor non-computer days. Hate to just throw parts at it, since
Honda parts cost twice what normal cars do, it seems. The shell is still
clean, so I was hoping to get another 5-6 years out of this thing.

 

Thermostat.

 

If the engine runs then it will generate enough heat to overheat in
short order. If it is overcooling than you have a bad thermostat.
Or you've somehow recalled the laws of physics.

 

Sounds like an open or missing thermostat. Not an uncommon thing to have
them bad out of the box. One of the reasons I test all the ones I buy
before they get installed.

If they are a good shop they will throw a scan tool on it before they
pull it apart. The tool will show if the gauge is correct or if it
really is running cold.

 

Why is it you think the car might suddenly acquire the wrong thermostat?
If changing the thermostat was part of the recent maintenance work, go
back and complain.

What you describe is exactly what happens with an stuck open
thermostat or perhaps even no thermostat. Probably it is stuck open
(unless for some reason they removed it). Extremely unlikely that the
gauge or sending unit is bad. Its pretty close to impossible, given your
precise description of what its doing, that it could have a properly
working thermostat and a bad gauge or sending unit.

-jim

 

Appreciate all the replies, everyone. I was hoping it was something
minor like that. Unless we get a warm spell, guess I need to take it
back to the shop. :^(

 

One further question - does the heater output coincide with the temp gauge?
That is - does the heater take forever to get warm and only put out warm air
or does the heater seem to work as it should? If the heater is working
normally, the best guess would be either the sending unit or the temp gauge.
If the heater isn't working as it should, then the best bet is the
thermostat.

DaveD

 

I'd suspect the T-stat.it's probably stuck open.
I doubt they changed it during the timing belt service.

--
Jim Yanik
jyanik
at
localnet
dot com

 

....or they removed and never replaced it..

JT

 

Tested that today, by driving the car to work. Heater seems to work
fine, and blows warm within a couple blocks, and very warm within a mile
or so. (Car lives inside the attached but unheated garage, so the start
temp is warmer than a car that lives outside. Has to be subzero for the
garage to freeze hard.) All this with temp gauge on or slightly above
the peg. Gauge does still move a little, if car is stopped and idling.

Still too sniffly to get out there with a flashlight to see if I can get
to the temp sensor, with all the other crap in the way. No hurry at this
point, I guess- I can wait for a warm day, especially if the snow they
are forecasting for later this week actually happens. This is my road
trip car, and I don't have one of those for awhile.

 

Toss a scan tool on it and see what the sender is telling the computer.
If it is OK then ignore the gauge. May be possible to borrow one from
some of the parts places. Just ask them if it will read live data as well.
You could have a bad sender to the gauge OR a bad connection or even a
bad gauge. A quick scan and you would know if you can just ignore it
until better weather.

 

Oh where are you located? If you are nearby I could scan it for you easy
enough.

 

If the heater appears to work fine, then the gauge is suspect. You need to
aim an infrared thermometer at the upper rad hose outlet from the head.
If, fully warm, you get much less than about 205F, then the engine is
running too cool.
If, fully warm, you get about 205, then the gauge is faulty.

It's a one-wire connector that's usually right under the distributor.
Should be easy to get at.

With the infrared thermometer showing about 205 at the "sweet spot", unplug
the sender's wire and push it aside. Using a VOM, connect the sender's
contact to a good engine ground. At full-hot, you should see 35-32 ohms. If
you see significantly higher than that (like 140 ohms), then the sender is
bad.

 

I'm sure you're referring to using the scan tool to check the ECT sender,
not the gauge sender.

Honda coolant-temperature-gauge senders (really just a variable ground) go
bad far more often than the gauge itself.

An infrared thermometer and a VOM are invaluable tools for solving this
problem.

 

Sort of like other breeds. EXCEPT the damn stepper motors GM stuck in
some vehicles....

True, just figured the scan tool was a "clean hands" option.

 

He's in the San Francisco area. Bit of a drive from the Birthplace of
Baseball...

 

Just a bit. I don't think the cable will reach either ;-)
Oh and don't believe that drivel about Cooperstown...

http://www.hobokenbaseball.com/
The first recorded game of baseball in US history officially took place
in Hoboken in 1846 between the Knickerbocker Club and The New York Nine
at Elysian Fields.

 

Now if I only HAD an IR thermometer.... :^(

 

Oh, that's only about 14 hours away, if I cut through Canada.... :^/
But thanks for the thought.

 

????
If you are referring to me (the OP in this thread), where do you get SF
out of anything I have ever posted? I'm in Baja Ontario, aka southern
peninsula of MI. (not a lot of Honda mechanics around here for some
reason...)