Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Overheat from cold start, heat on for only a minute, NO MORE high temp?

I cannot for the life of this car figure this beast out now.
91 Integra 201k miles.
New distributor cap, plugs, wires about one year ago.
New head gasket, water pump and timing belt app 7 mos ago…?ish?
New starter, battery cable, all three belts, fuel filter and thermostat from about 1 month ago to yesterday.
Starts out with a rising temp gauge when engine gets warm at idle. I turn on heat for a couple minutes, it stops.
No need to continually have heat on. Can even run A/C after if I want to!
Don’t have any rise in temp for the rest of the journey, not until car sits for a bit and journeys again. (couple hours perhaps)
A/C is cold, heat is hot. No loss of coolant. Mechanic (also perplexed) said fans working fine and when supposed to.
My next last ditch attempt is to flush radiator tomorrow.
Also, and maybe unrelated, maybe not,
Sometimes doesn’t want to start, takes either a few tries or 5 minutes.
Temperamental. Will crank but not turn over, sometimes S3 light flashes when in mode to NOT start and cranking. Check engine light intermittent as in maybe one morning, maybe not for 4 mornings. Whatever.
Believing this may be an ECU issue, (scared it is) but can’t figure if that would tie to over heating or not? Sensor wise maybe?
Good grief I have a headache over this…
Will not let red line, overprotective of my baby.

When you put in the thermostat, did you make sure the air bleed was located up? If it is located down to where it is below the thermostat pill, there could be an air pocket forming that is delaying the thermostat from opening. Once it opens, the air bleeds out and all is good until it cools and the air bubble forms again. I’ve seen this happen with imports and domestic cars. I usually remove the jiggle valve or checkball air bleed and leave a small bleed hole. This prevents that air bubble delay.

I did make sure that was up. It was all loose and wiggly. I also burped the radiator after filling back up again.

Have you pulled off the lower radiator hose and looked inside? These can collapse inside restricting flow even though outside of hose looks OK. When you drain the radiator to flush it this will be easy to do.

Also, have you tried a new radiator cap? And is the coolant overflow working properly, going into expansion tank when hot and being sucked back into radiator when cool?

Turning over and cranking are the same thing, the just mean the starter is turning the engine. What you want it to do is start or fire up.
Are you sure it is really overheating? Have your mechanic aim a temperature gun at the radiator while your gauge is rising and see if the temp is really going up.
Does this car have the original radiator? Radiators for this car are not expensive.

Is there an air bleed fitting on the head near the thermostat housing (like there were on my older Hondas)?
Did you bleed that?

If in doubt, do a compression test.

Radiator was replaced right before I bought it about 2 years ago. Previous owner was having overheating issues hence my job to get the head gasket replaced.
I’m assuming if it was just a radiator cap issue, it would be overheating more often?
It only does this from a cold start, only once. After a minute of the heat on, I can turn off and it won’t do it again. Just weird to me…
I do believe the expansion tank is working just fine.
Yes, I did bleed the valve by the thermostat as well.
This little guy is just keeping me guessing.
I am going to leave him with the mechanic overnight so he can replicate the issue as he has been unable to considering it only does it from a cold start.
I don’t ‘officially’ know for a fact it IS overheating but when you have had this issue of overheating and head gasket, water pump replaced, I watch it like a hawk and don’t see how far that gauge is willing to go. Its a red flag to me on a temp gauge that when running normally, doesn’t move a millimeter, ever.
Admittedly I have yet to flush the radiator yet because I can’t GET to the lower radiator hose and would rather do it that way that use the little valve. It’s going to involve some extra work.
I appreciate the attention to the matter, I’m running out of theories here! Thank you all!

Thermostat in backwards?