so i picked up a crx again. got a good deal. $1k 90/si clean title w/ 190k miles. everything original. problem was that the car has overheating problems. previous owner said usually once driven for some time 30-90 minutes, the car will start to over heat. i drove the car home, roughly 30-40 minute drive, 15 miles. no signs of overheating. well i need to get it smogged and i dont want it to start overheating while their doing it. i checked the radiator , fluid tapped off also checked for leaks , doesnt show any. im asking you guys, whats the best way to diagnose where the problem is?

 

does the inside of the radiator appear to be relatively clean? you could test the coolant to see if it has an adequate percentage of ethylene glycol in it. it could also be a partially blown hg which is leading to it overheating over time. is there any greyish sludge like stuff built up in the radiator fill area? you can get a kit to test for the presence of hydrocarbons in your coolant and that would tell you for sure whether you do or do not have a blown head gasket.

 

After you drive it around for a while let the engine idle and make sure that the radiator fan comes on.
Pretty typical issue if it doesn't.

 

I would say check the rad. Try to look in the cap and see if the tubes are clogged. This can restrict flow especially if its an old rad. I swapped mine out and the old clogged one was about 5 pounds heavier.

 

no build up or anything, although i looked at the radiator fluid reservoir and it looks really dirty, like some build up. so im going to test the fluid, hopefully it isnt a blown hg. also at idle, fan doesnt turn on. but when i turn ac on , both turns on. possible fan switch? thanks for the pointers!

 

On the back of the motor by the oil filter there is a connector with two wires in it.
Disconnect the wires from the sensor and then hook jump them together.
Turn the ignition to ON and the fan should turn on.
If it DOES turn on, then the thermal switch that the wires hook to has gone bad.
If it DOESN'T (not likely since it runs with the A/C) then it's wiring or relay.

It's the 2 prong sensor in this pic


The wires look like this
(This pic is from a car with an engine swap - sensor is in a different place on that motor so the wires are only there)

 

good lookin 4drEF. that was the problem. thanks!