Overheating Problem

[TURBOHHH]

ok i am lost! heres my problem. as i posted eariler i have a sock sr , front mount, metal head gasket, koyo, duel electric fans, nismo thermostat. ok i have replaced the temp. control sensor, and temp switch both today. ok heres the problem. i can ride around for about an hour then the gauge will start to rise up like i am overheating. when i pull over its not boiling over and my overflow tank is full of cool water. now if i get in the car with the gauge sitting almost on HOT i can turn on the heat with the recerculate off and the gauge will come back down. but as soon as i turn the switch to reseculate back in the car it will run the gauge back up. so confusing. i did a leak down test on it and it is holding and the water pump seems to be flowing water. ANY IDEAS? PLEASE HELP!

[Blown240sx]

Air in the system? Leak in one of the lines?

Take the radiator cap off and start the car see if it bubbles some and the collant level drops. If so add more until it stops and no more air.

[Rookieca18det]

^yeah im with Blown240sx, def sounds like you might have air trapped in your system. Had air in my system b4 and the temperature needle would act crazy.

[TURBOHHH]

thats what i was thinking but i have bleed the system like crazy, i mean seriously for an hour. so i pulled the termostat out and tried it with it out, because i new that would push all the air out still did it. damn this is nuts.

[fregisr]

There is an air release valve right around the yellow circle, Take out the air plug and keep on pouring coolant until it leaks out

[Nismo_Freak]

Better, but next time don't use all caps.

[TURBOHHH]

there is know making you happy is there NISMO FREAK? lol j/k ok well i have been tring for the past few days to figure this out, new sensors, bleeding the system, etc. ok well the other day i drove it around and it was fine but after about an hour of course the gauge started to rise again. ok well i turned the recurculate button off and turn the heat on and BOOM the gauge started to come back down. so last night i waited till it got really cool outside, also i turned my cooling fans on to run all the time, and i went out driving. ok i was out for a while doing a nice speed, but getting in the boost. gauge never moved stayed right where it was suppose to. also i left the recurculate button on, and left the heat off. so here is my question. do you think that when it was hotter outside and the fans were only running at curtain temps. that my heater core was acting as another small radiator? should i cut open my bumper to try to get more air into the radiator? also is it bad to leave your electric fans running all the time? i.e is it better to have them on a switch as to a termostat controller?

[dustyk]

I run my fans on all the time and I dont have any problems.

Also, your heater core runs coolant through it so blasting your heat will act like a small little radiator. I used to have to crank the heat in mid summer on my old car so it wouldnt overheat.

Also, can you give more detail about your swap? Is it an S13 SR in an S13 or S13 in a S14?

[bluesguy321]

I had the same problem with mine!!

What it was there is a coolant hose on the underside of the intake mani, and it had a pin hole leak in it. My car would over heat turning it on. there was very little signs that there was a coolant leak, until i went to change the oil and I saw coolant on the right control arm.

Long story short, and $369 later, the hose had a hole in it the size of a pen top. Maybe it is that, if you havent figured it out yet.

The hose runs from the return to the radiator, to the under side of the runners. You can touch it if you stick your and in between the 2 and 3rd runners in the little space between.

Maybe thats it????

[TURBOHHH]

I had the same problem with mine!!

What it was there is a coolant hose on the underside of the intake mani, and it had a pin hole leak in it. My car would over heat turning it on. there was very little signs that there was a coolant leak, until i went to change the oil and I saw coolant on the right control arm.

Long story short, and $369 later, the hose had a hole in it the size of a pen top. Maybe it is that, if you havent figured it out yet.

The hose runs from the return to the radiator, to the under side of the runners. You can touch it if you stick your and in between the 2 and 3rd runners in the little space between.

Maybe thats it????

well i have checked for leaks and stuff havent seemed to find any. now before you found it did you do a leak down test or anything? i did a leak down and it held and i couldnt find any leaks but i mean a pin hole would be hard to find. let me know. thanks for your help though. ill for sure check it.

[bluesguy321]

No i did do a leak down, i just follwed the trail of coolant that lead me to the hose. it was all over the oil filter that i changed so i put 2 and 2 together

[TURBOHHH]

No i did do a leak down, i just follwed the trail of coolant that lead me to the hose. it was all over the oil filter that i changed so i put 2 and 2 together

oh ok cool. well i will check it for sure. thanks again.

[nukeone]

Conclusions from what you posted, assuming that all air is vented from the system:

1) Overflow tank is full of cool water - means the radiator side of the cooling system is staying cool (i.e., stuck thermostat) or the radiator cap internal relief valve is not lifting (factory designed to lift at 11 - 14 psi). Feel the radiator, is it extremely hot to the touch - normally gets very hot but, if the thermostat is sticking, may only get warm (from engine heat).

2) Temp gauge goes down with heat on - indicates to me, again, that the thermostat is sticking. The heater core does act as a radiator. Remember that water is always circulated throughout the block, intake mani, and the heater core regardless of whether the thermostat is open or closed. Once you turn on the heater/blower fan switch, you immediately remove heat from the water, just as the radiator does, so the sensed temp will go down.

3) You said you pulled the thermostat and this still continues - blows my first 2 thoughts. Since the thermostat, when closed, blocks flow returning from the radiator, look for other obstructions. Identical conditions have happened to me and the fix was a new thermostat.

[Driver11324]

I hate to bring back old threads, but was this problem solved? and how was it solved? I have the same problem and its really getting me frustrated.

[mi240sx]

I have the overheating problem also and will try the thermostat, something else I was wondering is when I installed my SR. I used the fan clutch that came with the SR, does anyone know the temp rating difference between the SR fan clutch and KA. I also had a question about your crankcase breather coming off your valve cover. I see from your photo, you put a small breather on it, is the other side off the "T" plugged. I used a small hose, ran mine to the cold air intake in between the MAFS and the turbo.