Engine Temperatures

[Jarvis]

There's 3 different thermostats for the M20:
71, 75, and 80 degree, correct?
Are you guys all referring to the 71 deg. as the "low temp thermo" and the 80 as the "high temp thermo"? If so, I'd just go with the 75. My old E30 ran very low (above 1/4 maybe twice ever) and my new one heats up to 1/2 pretty quickly, and will go up to 3/4 given the right situation.
I don't like either. In my old car, the heat system wasn't as warm as I wished it had been in the cold upstate NY winter, and in the new I'm worried about it overheating.
New thermo's are only like ~$15-17 new. I'll give the 75 a shot after I order it this week and let you guys know what difference it makes.

[cahomey]

this is the reason why temperature is important in an engine. too hot is bad but too cold is equally bad -Although it’s important to keep the engine from overheating, it is equally important to prevent over-cooling. Over-cooling encourages the formation of acids and sludge in the oil. It also tends to reduce combustion-chamber temperatures by quenching the flame front. This results in higher emissions and greatly reduced fuel efficiency, because much of the fuel remains unburned. That’s why it is never a good idea to substitute a thermostat with a lower opening temperature than that of the one you are replacing.

I agree with you that temperature is important, but unless you have exact numbers, your comment is worthless. Not to mention all the variables in the equation.
Just going from a gauge renders no accurate information to what the m20's perfect operating temperature really is.

The only way to find concret information is to do tests.

[tonytony]

my car rarely sees pass about the 1/4 mark, even on the drive to the beach awhile back on the beach drive and I was mashing on it. I'ts always been like thta since I bought the car last year.

[royalflush313]

I have plenty of heat, it contributes to the such cool temperatures.
Any clue why the gas mileage drops? Or are you just relaying a delusive post you saw a while back.

Im commenting what I heard from a mechanic (a reputable bmw mechanic if that matters) that having a bad thermo does not need immediate attention, and that the only thing that suffers due to running a cold temp is worsened gas mileage and lack of heat.
My mechanic told me that the engine is more efficient at the operating temperature.

I replaced my thermo before the winter, and so I cannot speak about the heat. But, I can say that my gas mileage did go up.

So gas mileage is affected because engine runs more efficient at the optimal running temperature. All of this is according to my mechanic whom I put my trust before any of my stupid theories about cars

and this post is not my stupid theories about cars. I'm only speaking what I'm told, and what i personally experienced.

:)

EDIT: the change in gas mileage was not drastic. So I cannot blame the tstat as the sole cause.

[cahomey]

So your mechanic knows what temperature the m20 likes to run at? And he knows where that temperature sits on our gauges?

All I'm saying is how does anyone know for sure that running these engines a few degree's cooler, according to the gauge, makes any difference?

btw, please don't take any of my comments as threats. I am just trying to get to a conclusion.

[hotghias]

I have plenty of heat, it contributes to the such cool temperatures.
Any clue why the gas mileage drops? Or are you just relaying a delusive post you saw a while back.

i don't know a lot about our efi systems, but in general, your car runs rich during warmup mode. if you're always running cold, you're always in warmup mode.

and your car needs to heat up to burn the moisture out of the oil and a bunch of other stuff i'm sure.

so just go get a new thermostat. 15 bucks.

[hotghias]

this is the reason why temperature is important in an engine. too hot is bad but too cold is equally bad -Although it’s important to keep the engine from overheating, it is equally important to prevent over-cooling. Over-cooling encourages the formation of acids and sludge in the oil. It also tends to reduce combustion-chamber temperatures by quenching the flame front. This results in higher emissions and greatly reduced fuel efficiency, because much of the fuel remains unburned. That’s why it is never a good idea to substitute a thermostat with a lower opening temperature than that of the one you are replacing.

I agree with you that temperature is important, but unless you have exact numbers, your comment is worthless. Not to mention all the variables in the equation.
Just going from a gauge renders no accurate information to what the m20's perfect operating temperature really is.

The only way to find concret information is to do tests.

no need to insult the guy trying to give you advice. do you want him to pull percent sludge numbers out of his ass? sheesh.

you can disregard the input of all the people on here if you want. go perform your own test if you're not satisfied with conventional wisdom. i just wouldnt want to perform tests with my mode of transportation though.

[cahomey]

Not trying to insult anyone. Besides Derek is cool.
Can an engine even return to cold start mode after running for a while just by to much cooling?

I will most likely just buy a warmer thermostat to put my mind at ease.

[nando]

my car ran at 1/4 before I did the timing belt/water pump and a new tstat. now it stays just under 1/2 no matter what, although during a few hot autocrosses it crept past the 1/2 mark..

[cracker5947]

simply put: BMW (as well as all other manufacturers) spend millions of dollars designing and engineering each vehicle. It was designed to run at a certain operating temperature (usually somewhere around 190 degrees) for a reason. When it runs cold incomplete combustion occurs and emissions get higher while fuel efficiency decreases. And as im sure you already know, overheating is no good either. Designated operating temperature should be maintained to keep the best of both worlds. Thats just my $.02