Overheating?

[warpd]

My car is getting hot, too hot for me. I have a new OEM radiator I put on this summer, new water pump, Mr. Gasket 180* thermostat. The car will not stay cool it will never get all the way hot but sometimes it will get 3/4 of the way over. On the highway its fine it stays alittle above a 1/4 over on the gauge. Driving around town though it almost always alittle over halfway over, when I get on it hard it gets 3/4 of the way over. When I first got it with a 180* thermostat it would never go over the halfway mark. The fans come on too. I took it to a shop and they said it was running in the acceptable range at 210*, I told them "no you don't understand that is not acceptable for me". That was sitting in a shop too, not even after it had been run hard. I was thinking my FMS Underdrive Pulleys might be the problem, what do ya'll think?

P.S. It also stays cool with the heater or A/C on. I'm assumimg this is because the heater core acts as another radiator.

 

[86bluecobra]

yes probably your UD pulleys. thats what they do. they drive the water pump slower. 210 degrees is fine don't worry about that. water boils at 212 degrees when it isn't under pressure. so it hasn'e even got to boiling temp yet. your system is under pressure so it should be fine. by the way did you replace the rad cap? maybe it isn't holding the pressure in the system it once did.

 

[HISSIN50]

A real gauge is needed, even if just to troubleshoot this down.

Since this happens at all times, it suggests the radiator cant reject enough heat (if the gauge is accurate).

You know where I would start. Good luck.

 

[warpd]

Well like I said it doesn't happen all the time, at least not on the highway. Yes I replaced the radiator cap and I tested it with a pressure tester. The reason I replaced the radiator was it was doing this during the summer and I had a small coolant leak. It turned out the leak was from the plastic radiator neck and one day it got hot as usual and the plastic neck exploded. So no more coolant leak but its still getting hot like before. I understand getting a better gauge but the shop I took it to actually tested the temp and it was sitting at 210. I know thats not real hot but it seems hot for a car that was just started up and let idle and revved up alittle. I'm just gonna put the old water pump pulley back on and see if it cools down I guess.

 

[iblue]

Do you have electric fans? If so, ususally the radiator fan switch relay will only kick on once the car has reached operating temperature as detected by the temp sensor. So even though the themostat has opened up and coolant is flowing, the car will heat up to normal operating temperature while idling. At that point the rad fan switch engages the fans to cool the car back down. However when you are driving down the highway the airflow is substantial enough to push the car back down to the 180 degrees that is being regulated by your thermostat. I know of guys who modify wiring to the rad fan switch so that they kick on at lower temperatures (or just run the fans constantly via toggle switch / bypassing rad fan switch). Bypassing entirely may result in a check engine light depending on your car.

Hopefully this helps.

 

[HISSIN50]

Iblue hit along the lines of what I was. This issue does not just happen at idle (suggesting fan) or at speed (suggesting the radiator), etc. It is not constant, but appears to happen in various conditions, if I read ya right.

How was the temp tested at the shop, BTW? IR thermometer? 210 is not unheard of, if the car was hot, sat for a few mins (heat soak sets in and the temps actually escalate - this is normal), and then the car was tested while idling. If your fan is not quite up to par, it might have a hard time getting the temps back down while stationary.

We are just tossing out ideas since we dont know exactly what the car is doing. We let you pick or choose what sounds plausable, so take no offense by the things that we post.

FWIW, the last line of your opening post would make me want to confirm that the fan is kicking on full bore at whatever temp threshold it should (the fan should come on when the A/C is turned on. So if the fan is simply switched on, you report that the car runs fine, right?). That would be simple.

For me, with a 180 stat, I would want the fan to come on at ~195 and off at 187 or so, give or take a few. I will note that some controllers are not very well calibrated and dont quite do what they are suggesting they are (with regard to the temp thresholds and their settings).

Good luck.

 

[warpd]

I'm not sure how it was tested but it sat for about an hour before they did. I can tell you I have a new coolant temp sensor and a new fan control module. Forgot what its called but it is $140 and basically a black box that regulates when the fan comes on and and when it goes off. I have replaced alot of **** chasing this little bugger. I also think that perhaps it runs fine when the A/C is on because there is both a high and low setting fan speed. The high speed mode only comes on when the A/C is switched on.

 

[HISSIN50]

Ooops, I missed that you have a 95 (when you mentioned having replaced the Constant control relay module, that made me look).

You know that there was a recall on the fan/fan wiring, right? Just FYI since yours appears to work. If you see a circuit breaker on the fan connector, that indicates the recall was already done.

Here is the deal! Low speed does not kick on till 208*F - that is why you run as hot as you do. High speed comes on at 226, unless the A/C is on.

What you are experiencing is TOTALLY normal. The normal solution: Install a switch for the low speed and perhaps a switch for the high speed fan.

Always check things with your meter before tapping circuits. Here is how to install a switch or switches (so you can turn the fan on before you reach 208*F) :

For low speed activation, you need to supply Pin 14 of the CCRM with fused 12 volts. This is done with one switch.

If you want to be able to turn on the high speed, supply Pin 17 with a ground pulse. This is a separate switch.

You very well could probably get away with just a switch on low speed. If you do both, DONT leave both switches on. Given the issue with the high-speed fan connector overheating, for some I feel it is best to simply wire up one switch for low speed (omit the high speed switch - your choice, you can add it later if needed).

Anyhow, I am pretty conversant with the fan switches so let me know if you have questions.

Good luck.

 

[warpd]

Ok I'll have to try this and thanks for the help. One other question how come I hear about so many SN95 owners sitting right at around 190* with stock cooling if this is normal for it to be at a higher temp?

 

[HISSIN50]

Ok I'll have to try this and thanks for the help. One other question how come I hear about so many SN95 owners sitting right at around 190* with stock cooling if this is normal for it to be at a higher temp?

190*F is not normal on a stock cooling system. The stock rated t-stat doesnt even open a good ways until it reaches 195*F. Add to that the paper-thin stock radiator (3/4-1" thick) and high fan thresholds (the latter was for emissions output), and they run hot in stock form.

Most of the guys who run under 200 while in-town have a 180* stat, along with a fan switch, stand-alone fan controller, or have flashed the puter and changed the fan turn on temp. Not to mention other cooling system upgrades.


Simply stated, since you said it runs cooler with the A/C on, a fan switch should take care of it. If you want to do it a cool way, a variable controller would be neat and you would not have to worry about flipping switches.

My thoughts.

Good luck.

 

[86bluecobra]

i put a fan switch in my car to keep it cool in stop and go traffic.