Rep Power: 0

Hello group! I have a 2002 Civic Vtec with approx 183K on it. I have noticed that after driving at highway speeds for 15+ mins on the interstate my cars temperature rises when the speeds get below 55mph. I first noticed this as I exited the ramp and got caught in traffic for a few mins. The temp started to rise but would fall just as fast. It acted as if the thermostat was sticking and unsticking..... It has been intermittent and is hard to duplicate on demand. Both fans are working as they should, so I don't think it is a fan issue.
Here is what has been replaced to solve the problem so far:
New radiator
new thermostat
New water pump
new radiator cap.
Radiator was topped off and checked for air in system. I have taken a laser digital temp sensor(hand held devise) and pointed it at the thermostat housing while the gauge is peg in the hot position and the hand held gauge reads 170-190 degrees F. The fans cycle around 195-205 F.

Is there anything else I can try to "Fix" this problem?? Is driving me nuts!

Another thing that may or may not be related is this.....Last Winter the temp gauge would be in the normal range and it would still take a few miles on a cold engine to develop heat in the cabin. After about 5-10 mins, the heat would suddenly turn to cold without touching anything. It would continue to blow cold air for a few mins then without touching anything, would start heating again?????? Any help, or suggestion will be most appreciated.
thanks,
jeff

 
Rep Power: 185

With all the parts your through at it and if your coolant system has been properly bled of air, it's very likely a blown head gasket. These don't blow like a normal head gaskets if you're familiar with what people perceive as "common symptoms". Search the forum for blown head gasket and read the overheating issues sticky in this forum.

 
Rep Power: 517

Inaccurate temp sensor, I bet.
Dash gauge uses data that comes from the PCM.

Get a scanner that can display an engine data list. (Or maybe a Scangauge?)

Read the coolant temp, compare the temp displayed in the data to the actual temp at the upper water neck or end of head.

Let the car sit overnight, check this before the sun heats the car up..... check temps of ECT and IAT, they should read ambient temp and within only a couple degrees of each other. If they aren't, then at least one of them is wrong.

 
Rep Power: 185

^^^^^^Yeah...listen to him. Disregard what I told you.

 
Rep Power: 517

Why? I don't have any idea what I'm doing. I just typed out the first thing that pooped in my head. (no typo)....

Remember this (the very definition of irony):



The OP could have a blown head gasket, sure.
But I think his description isn't quite that. Yet.

 
Rep Power: 0

Thanks guys. I picked up a temp sensor today and plan on putting it on tomorrow afternoon. I would hate to have a blown head gasket simply b/c that's a whole lot more work!
I did notice the last time the gauge was showing hot that NO water was boiling out the over flow and the engine didn't sound or smell as if it was actually running that HOT...... I hope it is just a faulty gauge! Keep you posted.
P.S.....if there is any others suggestions, please keep them coming!

 
Rep Power: 185

I hope, for your sake OP, that it is a faulty sensor. I truly do, but as ezone pointed out, it could still be a blown head gasket. It's reality in this generation of civic unfortunately. Good luck.

 
Rep Power: 0

that sounds like a head gasket issue