"Random?" overheating problem

[davh]

ok, I've searched the other overheating threads but non seem to address this issue.

99 Civic LX, auto, original engine, 134k miles.

The car will randomly overheat (no steam, just the temp guage moves all the way to the H), I get it back to the garage to look for the problem and it does not reproduce. I drvie hard won't happen again, Drive in stop-n-go, also won't happen. Sees impossible to reproduce.

I have replaced...
T-stat (2x)
Radiator
upper hose
lower hose
bled system

Fan is switching on. No white smoke. Nothing in the oil cap.

BTW, at about 130k had the trany fluid changed, oil change, fuel injectors cleaned, changed dist cap, rotor, plugs, wires, and fuel filter.

I want to get another few years from this car, right now I'm at a loss. Any thoughts or recommendations on what to check next?

 

[Tseids]

are you getting hot air out of the air vents?

 

[civicSIcoupe]

any visible leaks from the headgasket?
is there any coolant in your oil?
what colour is your oil?
loosing any coolant?
history of your water pump (been replaced or not)?
has the coolant system been flushed?

 

[davh]

replies

when it overheats, yes, I can turn on the heater and get hot air out of the vents. I can also turn on the A/C and get cool air.

No leaks from the head gasket. Oil changed about 3 weeks ago, looks good. No coolant in it. The only time I loose coolant is when I replaced the t-stat and hoses. Didn't tighten the t-stat housing down enough and it leaked. Foud it pretty quickly and tightened it up.

Then expereinced another overheat incident about 3 days later.

Water pump has not been replaced. When I run it with the rad cap off I can see the coolant circulating.

 

[RonJ]

Try bleeding the cooling system exactly like this:

(This procedure may take 20-30 minutes)

1) Park the car on an inclined driveway with the front end higher than the rear. Or put the front end on jack stands.

2) Push the dash heater lever/knob to MAX heat.

3) Follow the directions in the diagram below

 

[davh]

Thanks for the tip, I'll do this tomorrow. What is this doing, bleeding out any trapped air?

 

[RonJ]

What is this doing, bleeding out any trapped air?

That's the goal.

By the way, never let the engine temp reach full HOT on the gauge. Turn the engine off if the temp gets beyond the halfway mark.

 

[davh]

Ok, its been running great. Apparently for the bleed the incline is important.

 

[davh]

did it again....

Ok this is just getting weird. Bled the system on an incline as discribed. Car has run great for a couple of weeks now.
Today, my wife called and said she is sitting at a light and the temp gauge is going above the half-way mark. It is starting to over heat. The light turn green, she goes and it moves back down. She turns on the a/c and it gets hot.

I don't understand why it will run great for a couple of weeks and then start this again.

Any thoughts would be appreciated.

Davh

 

[fwdpower]

You sure your fan is kicking on?

When you put your hand behind the radiator/behind the fan, do you feel air? This determines if the fan is pulling air or pushing air. It should be pulling.

 

[jcamb]

ive been having this same problem recently

 

[rebirth]

overheating

Did you check the heater hoses? I had oil leaking that could not be located(actually I still have it) but the heat from the leak burned a hole in my heater hose, I also had it happen recently, with a different hose but I can't remember the name right now. Maybe your fan is also not coming on, or something is unplugged. Try the simple stuff first.

 

[davh]

ok it just did it and I was able to verify the fan was NOT coming on. A wile later, the fan did come on. I turned on the AC and the fan went off.

Is this a relay switch or the fan itself?