Overheating issue, driving me crazy, please help.

[opponheimer]

I'm using a 3.8l Taurus fan on low speed. Stock ka radiator on an s13 redtop sr, with fmic. I've run this setup before on about 4 s13s and have never experienced problems.

The car overheats when:


accelerating under load
going under boost for periods of time
and doesn't overheat as bad when i have the heat on.


It doesn't smoke, it doesn't eat coolant, it has good compression. I highly doubt theres coolant in the oil. The car runs great.


I'm 100% sure there are no air bubbles in the system, the rad. has been flushed. The thermostat and the waterpump have not been replaced yet.


Please anyone?

[mjjstang]

I think you have pretty much answered your own question here. First off, it is only happening when you beat on it, I know when I am beating on mine, even with my Taurus fan on High, temp increases a little. You are overheating which means something is not working right, Since you have a solid setup save for possibly the Tstat or pump, then there you go. Change out the tstat, see what happens. If it continues then change out the pump. If it still continues and you KNOW there is no way you have air bubbles, then there has to be something in the system blocking the flow. I would still think about upgrading the radiator however to something better. I am running the Koyo Copper and could not be happier.

Also what temps are you considering overheating?

[opponheimer]

I don't have a numerical temp gauge, just the stock one.

Heres what i just spent the night doing:

Replaced stock 0.5" thick auto s13 radiator with a almost new manual 1" thick s14 radiator.
Replaced the thermostat.
Flushed and bled entire system twice.So I took the car out to simulate the overheating that I was experiencing earlier. The way I would get it to overheat was simply go 75MPH in fourth gear on an incline in partial throttle / low boost.

The temperature outside was about 15 degrees less tonight than it was today, and the car did not overheat at all after the simulation.. Don't know if that means anything, but I guess I'll know tomorrow when it gets hot out. I also drove it pretty hard on 14lbs of boost, in low gear, at high speed, still nothing... but again, it is colder outside.




Okay, if my changes did nothing, then the only thing it could be is what, the headgasket? How can i 100% verify it is the headgasket--- will a leakdown test show anything?

[SoloSilvia]

I havent seen much of this posted, but I always swap out the SR coolant temp sensors with the KADE sensors, and that always fixes your stock gauge reading! That is as long as everything is all good. If not you'd know by now! Good Luck!

[opponheimer]

I fixed the problem two days ago, heres what I did:

Replaced the radiator with an s14 thicker radiator, and replaced the thermostat. One of the two did the trick. My guess is the radiator because the stock one had rust built up in it.

[mjjstang]

Opponheimer, I think you cursed me. Today I went out and the temp was about 190, nothing worth worrying about, but I changed the water pump today so Ill wait till tomarrow to see what happens. Glad you fixed your issue.