'90 Civic hot after 1 hr highway trip, overflowing coolant

I drove my '90 Civic EX sedan 1.6L (180k miles, 5spd) on a 65 mile trip
last week (averaging 75mph, 3.5-4k rpm, no AC, ambient temp 85) and
about 5 mins after I pulled off the highway, the temperature gauge
slowly climbed to 2/3, up from its normal position at just under 1/2.
Once I parked, I heard gurgling coming from the coolant overflow
bottle. After about 4 hrs, I opened the radiator cap to check coolant
level, it was still topped off even though about a cup leaked out of
the top of the OF bottle. OF bottle was empty, however. I
trepidatiously drove home, this time keeping my speed at 60mph or
below, and had no problems.

This was the first time since buying the car last fall I drove it at
this speed for a prolonged time, have driven several 1/2 hr trips at
less than 60mph since and no problem at all.

There's no oil or HCs in the coolant, no coolant in oil, so I'm
relatively confident there's not a head gasket problem, but who knows?
This car's so old and only cost me $1000, so if that's the case it's
junkyard time anyway. I plan on changing the thermostat, coolant hoses
and rad cap this weekend, and possibly the thermal switch that controls
the fan... don't recall ever hearing the fan run so that might be the
problem right there (anyone know off-hand where this switch is
located?). Perhaps the airflow at 70mph was enough to cool the engine,
but after heavily taxing the engine for over an hour the flow at 30mph
wasn't enough since the fan wasn't working? Maybe a collapsed lower
hose? I changed the timing belt this spring and did water pump change
then too... also, radiator is relatively new (according to previous
owner).

One other problem (maybe related, maybe not): I have noticed an
intermittant squeal coming from the front left wheel that is in time
with wheel rotation, and is more pronounced when I turn left. It's
quiet during right turns, and whenever I apply even light brake
pressure. This noise was very pronounced when it was running hot after
the first half of my trip last week (only after I got off the highway
and was driving for 5 mins at ~30mph on city streets). Possibly coolant
leaking on brake pad/caliper?

 

The coolant overflow system did its work.

Your radiator may be plugged up, or your water pump may not be working
correctly. Either way, your coolant isn't getting cooled by the outside
air well enough and the system is overheating.

A quick look inside the radiator will tell you if the radiator is
getting plugged up with gunk and needs replaced or not.

CV joint is bad. No big deal. Buy a rebuilt axle and be done with it.

 

Gotcha.

The radiator doesn't appear gunked up, but it's very possible. The
filler neck comes out at an angle and doesn't allow one to look down
inside like the rad on my old Toy pickup. No obvious white
scaley-looking crap though. I'll probably have it checked/flushed at a
local radiator shop after I change the hoses, etc just to eliminate it
from the equation. The cap is definitely old and the rubber seals are
cracked so I know at least that needs replaced.

The CV boots still appear supple, not dried and cracked, and no grease
leaking out... I thought a bad CV joint would produce a
"clack-clack-clack" sound during turns and not a squeal, but maybe it's
just not to that point yet. I think I can get a rebuilt axle shaft for
$80 at Pep Boys, so that's not too bad if it stops that infernal
squealing.

Thanks for the advice...

 

My daughter's 95 Civic had a similar problem with overheating, no
oil in the water, no water in the oil, reasonably new radiator,
timing belt/water pump replaced in the last year, etc. There
was a head gasket problem, and replacing it fixed the overheating
problem.

 

First check the top radiator hose. Is it hot when the engine is hot.
If not you have a sticking t-stat.

Second, unplug the radiator fan behind the fan and go directly from
the battery to the leads on the fan connector (the one connected to
the fan) and see if your fan turns. If not that is your problem,
replace the fan motor. With a car that old, the brushes in the fan
motor may be worn out. Recently happend to me.

But if it turns then you should check the thermoswitch. Trace the
wires from the fan motor to the t-switch and you will find it. should
be close to the t-stat housing, at least it is on the accord.

Frank

 

I've got the same overheating problem... I replaced the radiator and
thermoswitch last spring and the problem was fixed - or so I thought. Just
today, however, I experienced overheating that occurs when sitting at a
stoplight for a long period. My radiator fan does not come one. I may
re-wire it to always be on when the engine is on.

 

Replace your rad cap. That's the #1 culprit here.

The giveaway is that the coolant sucked itself back in after the car cooled
down. If it had been the head gasket, there would have been air in the rad.

Use OEM only. Toyota sells the same cap for cheaper than Honda. Ask for an
'86 MR2 rad cap.

Possibly rotor perimeter rust rubbing on the anti-rattle spring when the
rotors heat up. Pull caliper and check for shiny spots on the pad slide
shims where they tuck inside the mount bracket, and on the anti-rattle
spring embedded in the caliper.

 

Then you will have a problem of not having an engine at optimal operating
temperature as you will
be over cooling it. Thus your gas milleage will suffer and if you have to do
any smog check, you will fail.

 

same as some subarus too. nippon denso. was in a junk yard this
weekend - found all the [good] honda caps gone, all the [good] toyotas
gone, but the subarus, plenty of pickings!

 

In my 94 the thermostat is on the engine side of the *bottom* hose. Top
hose got hot, bottom remained cool after the point at which he
thermostat should have opened. Thermostat was stuck, and I was
experiencing overheating similar to what Bruce describes.

Try replacing the thermostat first, Bruce--simple, cheap, and why spend
good $$ on the other stuff when it could just be the thermostat? ;-)
Solved my overheating.

Also, remember your heater: it doubles as a radiator when your
thermostat sticks. Set the heater/defroster on full blast and watch your
temp gauge drop (as long as you aren't accelerating a lot, that is).

 

Nightdude wrote:

Then you will have a problem of not having an engine at optimal
operating
temperature as you will
be over cooling it. Thus your gas milleage will suffer and if you have
to do
any smog check, you will fail.
----------------------------------

Stop and think, the fan doesn't control the engine temp,
that is done by the thermostat. In older cars,like my 1985
Celica the fan is driven by the alt belt and is always running.

Or think about the air moving through the radiator whne you
moving. 30Mph forces a lot more air then the dinky little
cooling fan could ever move.

It would be better to repair the electrical problem that is
not starting the fan on demand, but his idea will work.
It will also really shorten the life of the fan motor. But in
ho tweather it might be worthwhile until he can get the
problem fixed.

Terry