Okay so I bought a 92 prelude. Just dumped a jdm h22a in her. And have been having overheating issues. I changed the head gasket. Had the head machined and all new seals and gaskets and valves. So I have a fresh top end. Put in arp head studs to boot. Thermostat is good. Checked 2 of them externally and both operate accordingly. Also has brand new water pump. New temp sensor. No coolant leaks. Also bled properly through bleeder valve on thermo housing. Boths fans are running 24/7 cause I have fan switch jumped cause sensor is no good. No Brainerd there. Got lots of heat in the cockpit. Everthing seems to be fine. Will sit at normal operating temp at idle and start overheating sporadically as soon as I start driving. Once it says it's too hot I jumped out with a temp gun and says everything is at roughly 153-170 degrees with is more than fine. I thought I have all bases covered here and am stumped now? Need some help if any! Thanks.....

 

try swapping your coolant temp sensor with the original sensor that was on the original motor for the car.....maybe the sensor in it now is sending a different signal then the original sensor does...giving you a false temp reading
I dont have a lot of H series knowledge so im not positive if the temp sensors work differently with different cars/generations... i dont think they would be different but its simple enough to try and its worth a shot.....

also its possible that you still have some air in the system...i know you said that you bled the system but sometimes cooling systems can be very stubborn....just a little bit of air trapped somewhere can cause an inaccurate temperature at your gauge cluster along with plenty other headaches...... make sure that the thermostat is OPEN and the motor is nice and warm when you bleed......rev the motor a bit while bleeding...this way the water pump will circulate the coolant and help push any air pockets that may be trapped somewhere...let it idle for 5-10 minutes and bleed again!

If both the upper and the lower radiator hoses are hot then that means your thermostat should be OPEN...another indication that your thermostat is open is your cooling fan will cycle on and off....it may take a while for your lower hose to warm up (or it may not even warm up fully) because you have your cooling fan constantly running...maybe disconnect it temperary just to help everything warm up, you should really replace that fan switch so the fan cycles on and off properly, when the fan is constantly running the motor has a hard time reaching normal operating temperature or its possible it wont even warm up completely.... the motor can be OVER cooled - not good for efficiency or for overall performance, this can also cause the thermostat to open partially or to not open at all resulting in overheating...

cooling systems are very picky...if every component isnt working properly with each other then you will have headaches

after all of that...... lets keep things simple and change your radiator cap

 

Awesome! Thanks for the tips! I'm gonna go grab a new fan switch and rad cap ASAP. And I'll bleed the coolant system as you said. Check all my ground wires and see what happens. Thanks again. I'll post my progress after I try all this.

 

no problem bud...good luck !

 

Hey just curious. When you said bleed it while the car is running should I have the rad cap on or off?

 

it shouldnt matter as long as the radiator is topped off so no air can make its way into the system....but cap it so you dont make a mess with coolant spilling everywhere, as the motor warms up the coolant will expand and overflow if the cap is off....make sure your expansion tank has coolant in it

 

good luck

 

Okay round 1 results.... Nothing changed??? Still overheating as soon as I start driving the car... What now? New etc sensor. Coolant temp sensor. And fan switch installed. Bled coolant system again..m
Just curious if I open up the bleed valve while the engine is running will thatpush out extra air pockets or just sick air in?
I need help good weather is here and wanna drive my lude!!!!!

 

what did you shoot with the temp gun?

 

Idling sits at 130-150 range. at the thermo housing its around 150ish. Upper rad hose connection to the cylinder Head is at 140ish. And coolant at rad cap is at 130ish. After driving for 2 min jumping out with the heat gun when the temp gauge says it's too hot. The thermal gun reads between 170-190 @ those 3 points with should be all around operating temperature am I right?

 

the ECT sensor does not control the coolant temp gauge. The one wire plug next to the ect sensor is the probe for the gauge.

get the online manual test procedures for the temp gauge

 

btw, the online manual can be found in the prelude section FAQ sticky

 

Would you know where I could obtain this online manual test procedures for the temp gauge?

 

Oh okay thanks.

 

I had the same issue last year, my problem was motor to chassi grounds were all f***ed that fixed my issues, hope ya figure it out !

 

Perfect! New project for tomorrow thanks eh!!
Round 2 begins! Posting possible success story tomorrow evening hahaha!

 

Okay so there is a god! Route of all evil was nothing but shat ground cables! Thanks man!!! So all you guys out there having weird overheating issues. Check your crusty ground cables, clean up all contacts beef up the wire size and Boom! . Happy Hondas and happy Honda drivers!!

 

Sick!!! I'm happy it worked !!! It took me a long time to figure out!!!!!! Yeaaah buddy!!!

 

Ha thanks!!!! I'm ecstatic it worked and that's all it was. LOL took me some time too. A good couple months or more at least for me till you told me. Thanks again eh!

 

Gonna take er down the highway now after driving around town for a few hours!