Rep Power: 0

2002 Honda Civic Ex 4 door.

Been trying to trouble shoot this problem for about a week. Had a thread here about having no heat after a radio install, but have new symptoms/info so I figured I would start over.

My wife noticed that she had no heat when engine was just idling. From what I've read here that's a bad sign.

When driving it, the temperature will climb to about 2/3 and then drop back down. It will do this several times in about a 5 mile trip. Every once in awhile, the temp will take off and get almost to the red line.

I don't think it is losing coolant, or if it is its a very small amount. The oil is not milky at all. The car runs great, plenty of power.

The cooling fans are kicking on when I start the car, but will not come on again, even when the car is hot.

After I cut the car off, it looks like there are a few bubbles coming up into the collant overflow, but it does not spill over. Just seems like a little air.

After reading the overheating thread/sticky, I'm thinking the thermostat may be shot, and letting in tiny bits of air. Also, maybe the fan cut on switch, (in the thermostat I believe) is shot and thats why the fan isn't coming on.

I will probably replace thermostat, radiator cap, and fan switch. Sound like a reasonable course of action? Not sure of the fan switch's location. Is it on the radiator hose side of the thermostat, or the block side? There are two connectors and I wasn't sure which was which.

 
Rep Power: 185

So basically you're going to ignore everything ezone already recommended to isolate a bad head gasket and go ahead and fire the parts cannon.

Good luck with that.

 
Rep Power: 517

Not possible.

Could be. Diagnose them.


On the thermostat housing. 2 wires. A green and a black.
Turn the key to ON, don't start the engine. Pull the connector off and jump the terminals with a wire. If the fans run, then the only thing you didn't check is the switch itself.




Wait for it..................







Had to happen.
Actually yes, but maybe none of those are the problem.


Test for a blown head gasket. Search for any of the dozen+ posts I've made that describe my method.

HTH

 
Rep Power: 517

Wow, I didn't even realize this was that poster. LOL

Gratuitous pic of the parts cannon was in order.

 
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it could be because of power supply damage or because of any disturbance in motors of the coiling fans.

 
Rep Power: 517

Am I the only one that read that as "A disturbance in The Force"?

 
Rep Power: 185

LOL, nope. I saw it too.

 
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Ezone and others,
Can it be a blown head gasket without losing coolant?

I did the parts store exhaust gas test but it showed fine. I realize I havent pressurized the cylinders as you suggested, but I only have an air tank, not a compressor.

The reason i mention the thermostat letting in air is from the overheating sticky at the top of the main page.

 
Rep Power: 185

What is this power supply that you speak of?

 
Rep Power: 185

Simple answer yes, but the coolant leak may so minute you may not notice.

A tiny amount of bubbles showing up in the reserve tank is just the beginning....probably. Those air bubbles are probably coming from one of the pressurized cylinders and pushing air into the cooling system because of a failing head gasket.

 
Rep Power: 517

Yes.
It DID lose coolant though. Just pushed enough liquid out of the radiator to let the bubbles go into the overflow bottle. And get an "air" bubble trapped in the heater lines or core.

That's why I can't use that for a test. Unreliable and inaccurate.


Funnel-fill radiator funnel (google that) stuck in the radiator. Engine running and coolant stabilized. Watch for bubbles. Any bubbles at all are bad news.
Doesn't matter. A stat cannot let air INTO the cooling system.
Unpossible.

 
Rep Power: 0

Thanks guys. Will try and round up a rad funnel and be back later with results. Appreciate the help. Why would the fans not come on even when the thing is close to pegging the temp gauge?

 
Rep Power: 517

This is what I use


http://www.amazon.com/Lisle-24610-Sp.../dp/B001A4EAV0


The check won't work right if you just stuff any old funnel down in the radiator neck.


I have modified the adapters just a little bit too.

 
Rep Power: 517

Depends.

Is the coolant at the fan switch hot? Maybe (probably?) not.

HINT: The fan switch is nowhere close to the coolant temp sensor that the gauge and the computer use.
It could still be nice and cool, while the temp inside the head is past boiling. The fan or switch may not be having any problems at all.



HTH