Which Thermostat Is Best?

[usualdeviant]

Anyone ever had problems with an 80 degree celsius t-stat from bavauto.com? seems i just replaced mine 2 years ago and now it's bad. goes right up to 3/4 on the temp guage with my a/c on. granted it's hot as hell outside, but come on. shouldn't the needle still be less than half way? new water pump because it leaked, radiator feels hot all around. i even replaced my pressure cap, and nothing changed. pretty sure it's the thermostat. anyway, which one should i get? autozone work ok?

[Cronopoulos]

Anyone ever had problems with an 80 degree celsius t-stat from bavauto.com? seems i just replaced mine 2 years ago and now it's bad. goes right up to 3/4 on the temp guage with my a/c on. granted it's hot as hell outside, but come on. shouldn't the needle still be less than half way? new water pump because it leaked, radiator feels hot all around. i even replaced my pressure cap, and nothing changed. pretty sure it's the thermostat. anyway, which one should i get? autozone work ok?

I had bad luck with an autozone one before, spent the extra $$ money and went with OEM 80*C.

Also, check to see if you have any air in the system and if you have the spare time, boil the thermostat to see if its opening..

[Herr Faust Schinken]

You might want to consider a 75 degree tstati know it gets really hot up in sac in summer

[paperplane94]

Op, Are you sure there is nothing else wrong with your system?

[usualdeviant]

I wonder how much it costs for an OEM one... I should boil it though. Draining and filling coolant is getting old these days... System is bled. Different thermostats only affect when the thermostat opens (warming up the engine), and don't have anything to do with normal operating temperature, am I right? At normal operating temperature (and above), all thermostats should remain fully open, right?

[Cletonius]

I got an 80c one at o'reilly that was stamped made in Germany, i forget the brand now but the box says made in china. I haven't installed it so I can't say how well it works. I'm still trying to decide if its actually made in Germany or if the chinese copied it down to the "made in" stamp. Maybe just the box was made in china?

Thought you should know.

[sayed ali]

Get a 71*C T-stat and enjoy :)

[cabriodster87]

Different thermostats only affect when the thermostat opens (warming up the engine), and don't have anything to do with normal operating temperature, am I right? At normal operating temperature (and above), all thermostats should remain fully open, right?

When a cooling system is operating properly, thermostat fluctuation maintains engine temp.

[jlevie]

If the engine is running hot at speed a bad thermostat or clogged radiator are likely suspects. If it only runs hot when idling the first suspects would be the fan clutch and aux fan.

[usualdeviant]

Totally. Well I read that a 71* C t-stat is for race applications only... So I'm still not sure. I also read that BMW included most cars shipped to the US with the 80* C one. Not sure which one to go with, here. I like my temp needle to sit at the first mark before halfway. You know, like most cars do. So assuming my radiator isn't clogged, (my overheating problem is runs hot at all times after warm-up), shouldn't the 80* t-stat do it for me?

[jlevie]

Assuming this is a car with an M20 engine, the standard thermostat should be an 80C unit. In which case the needle should rest between the 1st mark and half way point. A 75C thermostat will result in a normal position closer to the 1st mark. If the needle is resting above the half way point something is wrong.

[paperplane94]

Assuming this is a car with an M20 engine, the standard thermostat should be an 80C unit. In which case the needle should rest between the 1st mark and half way point. A 75C thermostat will result in a normal position closer to the 1st mark. If the needle is resting above the half way point something is wrong.

That's what I was thinking.

An 80 degree thermostat should not cause the car to be that close to overheating.

[usualdeviant]

It's an M20B25 and I would boil that thermostat right now if I had a thermometer! Yes, it goes up past half way and it may just go all the way to the redline if I let it. But I'd rather not ignore that bit of common sense I have left. Anyway pretty sure it's the thermostat since I don't see how a radiator would suddenly get all clogged up. I recently replaced coolant more than once and had no problem draining it or anything. I guess I'll go with a wahler 80* C t-stat this time (pelican parts). hopefully it lasts longer than 2 years. I actually read the reviews and one customer said it does come with the o-ring even though it doesn't say so.

[Mr. Tasty]

So would you guys recommend a cooler than 80 for a daily driven arizona car? or stay 80c?

[jlevie]

So would you guys recommend a cooler than 80 for a daily driven arizona car? or stay 80c?

The engine will be a little more efficient with an 80C thermostat and if everything is working correctly you won't have a problem with the engine running hot with that thermostat. You can use a 75C thermostat, but under load in hot weather the engine will reach about the same temperatures regardless of which thermostat you use.