car overheats!!!

[s13rb25det]

alright! I just got a new t-stat housing and hooked it up with a new nissan t-stat, and took my car for a drive, I got on to the highway and and it was fine for a little bit and then it started to over heat! I then drove it back to my house and removed the t-stat and then drove it again and it still overheats! I have comperssion tested and checked the motor with vaccuum and it was all good 120psi on all cylinders and my vaccum gauge doesnt dip or any thing, so Im sure my head gasket is fine! it only oveheats when Im on the highway which makes me think its the T-stat but its not! I have purged the cooling system and I have no leaks at all! I have noticed a little bit losss of power like I lose boost at higher rpms could this have any thing to do with my motor overheating! could it be in limp mode or something and is making it get hotter or something? thats the only thing I can think of beside mabye a bad water pump or poor air flow through my radiator? have you guys had a problem like this? its driving me crazy!!!!

[Joe]

bleed your cooling system

check for blockages on and in the radiator

and no limp mode wont make you overheat, the ecu has nothing to do with your cooling system, your power loss IS related to the overheating tho. do not beat on the car when its overheating you are inviting a catastrophe

[420_240]

I'm gonna say water pump is your issue....The blocks are iron so they tend to make the OEM pumps rust and corrode over time... and if you haven't replaced it with a fresh one... you're basically gonna flush all your money and time down the $hitter.

[Real Boring 240]

imma go with 420 on this one. sounds like a mechanical device such as a clogged radiator or bad waterpump. Not like you have tons of parts to troubleshoot with the cooling system!

-Rafael

[Yellow4g63]

might be a headgasket. 120psi on a RB25??? it should be higher than that.

[Joe]

might be a headgasket. 120psi on a RB25??? it should be higher than that.

first you have to assume he did the test correctly

this is why compression tests suck, there are so many variables. was the engine warm? was the fuel system disabled? what about wide open throttle?

leakdown test > all

[Bluefire]

Keep bleeding the system. It might be easier to if you lift the front end. Also Check to see that your radiator hoses are getting hot.

-Bluefire

[s13rb25det]

yeah, I thought 120psi was a little low also but that is about average! the specs say 173psi but I have never heard of a rb25det with over 135psi there mostly around 110-125psi and yeah I did it right!! the engine was warm, fuel and spark were disabled, and I held the throttle at WOT. all cylinders were at around 120ish also i show NO signs what so ever of a BHG nothing!!!! I have flushed the cooling system a few times now and put in 50/50 coolant I have a upgraded koyo radiator? I dont know how that could make the car overheat but Im running out of Ideas??!!!!! I will change my waterpump today and also my radiator cap and see what that does!! keep the answers coming in!! thanks Roger

[Joe]

yeah, I thought 120psi was a little low also but that is about average! the specs say 173psi but I have never heard of a rb25det with over 135psi there mostly around 110-125psi and yeah I did it right!! the engine was warm, fuel and spark were disabled, and I held the throttle at WOT. all cylinders were at around 120ish also i show NO signs what so ever of a BHG nothing!!!! I have flushed the cooling system a few times now and put in 50/50 coolant I have a upgraded koyo radiator? I dont know how that could make the car overheat but Im running out of Ideas??!!!!! I will change my waterpump today and also my radiator cap and see what that does!! keep the answers coming in!! thanks Roger

the few ive compression tested are in the 165 neighborhood

mine was 160-165 on all, 120 is NOT normal. try a different compression gauge. but the number isnt important, its the variation from cylinder to cylinder. if they are all within 5-7% usually nothing is wrong unless the compression is incredibly low. i would do a leakdown test on your engine if i got numbers in the 120's.

[s13rb25det]

yeah i have bled the system a few times already also! I will keep doing it though! and my top radiator hose is very hot, and the lower hose that goes to the t-stat is luke warm? thats the way it should be right? thanks

[s13rb25det]

165 psi? really??? thats weird, mine just stays solid at mid 120s on all cylinders!! mabye I have a upgraded thicker head gasket? the comp. gauge I have is alright its a older model snap on I will try it with another gauge and see if it changes! thanks

[s13rb25det]

I think I found the problem! I had worked on my fans and radiator a few days ago and i hooked my fans up backwards!!!! so its blowing instead of pushing the air though the radiator!!! but while I was trying to diagnos this problem I burnt my hand real bad!!! on the exhaust!! so Im pretty worth less right now!!! any way I hope this fixes the problem!! because there is no wayI can work on it now!!!!

[CKs240sxNC]

Thermostat

[s13rb25det]

yeah that seems to have fixed it!! I drove it about 35 miles with no problem!! I am going to flush the system again and seal the radiator a bit more so it gets better flow thanks guys!!!

[JonPowell]

Isnt it funny how most of the time its the last thing we forked with that causes the problem.

Thanks for listing all the stuff you had done to the car to help us eliminate the problem and above all thanks for wasting our time & brain power to troubleshoot a problem that you didnt fully describe.

On my S13 RB25DET with stock S13 radiator I never had a heat problem while driving and I only had the fans on when sitting idle for a while like at a drive through or something. You probably still have another problem.

[Slo_240sx]

haha its always something we touched last!!! I think he also has enough !!!!!!!! at the end of every sentence!!!!!!!!!!!!!!!!!!!!

[goofynick6]

I was going to suggest the easiest solution...did you swap temperature gauge sensors from your ka into the RB?

[s13rb25det]

yeah I swaped temp gauges from rb to ka that helped it be a little bit more accuate, it also showed that it got up to temp faster. thanks for the help guys, Im sorry it was just a goof on my part! later