New advice on Thermostat

[MattBimmer]

Alright guys starting monday I am going to replace my radiator and my thermostat. I bought an original OEM radiator as it was much cheaper than the aluminum radiator (70$). My biggest concern comes to buying the new thermostat.

I bought all this stuff because my rad. has a leak, and the temp gauge had been creeping up to 3/4 at stop lights.

Now the REAL question I have is should I buy the 180 degree T-stat or should I buy the 172 degree T-stat. I have read that the 172 makes the car run between the 1/4 and 1/2 marks. Would this cause problems? I mean it wouldn't really reach the proper operating temp if I use the lower temp t-stat right? OR is it safer as it does a better job of lowering the temp.




Also anybody have advice about whether or not to use Blue coolant, or just standard green coolant.

[BigTe30]

i run prestone premix, a fresh OEM radiator and a 172 thermostat. My car runs right at the mark to the left of center, and creeps up to halfway between that and the center mark when stopped.

[MattBimmer]

yeah thats what I have read. I mean is that not good that it never reaches the optimum temp? But the coolant. I read that for 91 on it is important to use the BLUE coolant as it doesnt have corrosive molecules like nitrates and shit like that.

So in your opinion if I want to guarentee that I don't creep into that hot area go with the 172.

Also how is your heat in the cabin. Is it cozy warm or slightly warm.

[MR 325]

I always run the OEM temp thermostat. Most people running lower temp thermostats are trying to band-aid something else wrong with the cooling system. With the colder thermostat the engine will not run efficiently. It will effect performance and fuel economy.

As for the coolant, you can run either. I run the BMW coolant but it's not required.

[Bearmw]

Doesn't BMW offer different temp t-stats for our cars (m20, m30, etc.) and was that for "band-aid" fix or another reason? What compromises is BMW considering?

[jlevie]

Your choice of thermostat (70, 75, or 80C) has very little to do with whether the gauge will "creep into that hot area". If there is a problem that is causing the engine to run hot a lower temperature thermostat simply means that it takes a little long to get to the "hot area".

If the climate is such that you seldom need heat and mostly use A/C a 75C thermostat will be the better choice. In a colder climate where cabin heat is needed, use the 80C thermostat.

[603Racing]

If your temp gauge is creeping when you are going slow or at a stop it can be a sign of a bad fan clutch.

The best thermostat in the world isn't going to keep your car cool if the entire system isn't functioning properly.

[priapism]

Is it better to run a cooler t-stat on a car that only sees track / competition use?

[jlevie]

Is it better to run a cooler t-stat on a car that only sees track / competition use?

The lower temperature thermostat isn't going to result in lower steady state engine temperatures on track. That will strictly be a function of ambient temperature and radiator efficiency. Well that is true except in pretty cold weather. My Spec E30 settles at about 195-200F in the summer and 180 in 60F weather using an 80C (176F) thermostat. I use the higher temperature thermostat since engine efficiency is better at higher temperatures and thus the car makes more power in cooler ambients where the thermostat is pretty much in control. The 80C thermostat doesn't hurt in the summer as the engine will be at around 195 regardless.

[priapism]

We race mostly in the heat here, sometimes ambient temps get over 110F. I have a new radiator in my Se30.

I knew I had a new thermostat in my street car, I guess the guy put a 76 in there. I'm going to grab an 80 today.

[MattBimmer]

Thanks for the input. I am replacing all this because of the leaky radiator, I have to refill it whenever I move it from my moms to my dad. My fan still works fine. Hopefully the new radiator and t stat will keep her cool :)

[priapism]

My car had always run on the low hash mark (the one to the left of "normal" but to the right of the cold one). I assumed it had a 70c or 75c stat in there. Turns out it had had an 80c all along, yet it still runs cold. Hm.

I put in a new 82c for poops and giggles, turns out it was slightly too big, now the car is making a noise. Figures. Should have left well enough alone haha.