How bad is a stuck open thermostat?

[dcardenas]

Something I should replace right away?

[beatniks325]

simply put, yes! there seem to be alot of thermostat questions lately, it must be this time of year with the colder weather??

[LagunaSecaBlue]

yeah i waited a few weeks to change mine... the car ran alright during the day and for city driving but if it got cold out or i hit the highway the temp gauge droped. it's really easy to do and should only take 4 hours if it's your first time and you're replacing coolant too. make sure to get a 32mm (if i remember) wrench that's really skinny cuz it's a tight fit to get your fan out.

[vml]

snip it's really easy to do and should only take 4 hours if it's your first time and you're replacing coolant too. make sure to get a 32mm (if i remember) wrench that's really skinny cuz it's a tight fit to get your fan out.

It's even easier than that because he has an M44 engine, which uses an electric fan so no need to remove the fan. The only thing is that the thermostat for this engine is more expensive because it comes integrated with the thermostat housing.

[bimmer95]

Should take under an hour to swap out, the M44 thermostat is way easy to change out. Definitely do it ASAP.

[Hollywood Hamilton]

I just did mine and it made a world of difference. I switched to the orange coolant as well. I know I know, save me the "Orange stuff sucks" flames.

[bz94z]

Is the M44 the 4 cylinder? I have the same problem on my 94 318is...

[bz94z]

Is the M44 the 4 cylinder? I have the same problem on my 94 318is...

[DNK]

94 318s are M42s. I believe you will still have to remove the fan for it.

[scooter086]

i've been driving with a stuck open thermostat since last winter, is it really that bad? all i've noticed is a lack of heat in the car when its below freezing out. how much do you think this work would be at the dealer? i'm too lazy to do it myself right now.

[bimmer95]

i've been driving with a stuck open thermostat since last winter, is it really that bad?

Yes, it is. When your engine is below normal operating temperature the ECU leaves the A/F mixture in warm up mode, meaning running rich. Running rich all the time uses up a LOT more fuel, fouls out your O2 sensor and will eventually foul out your cat. Those can turn a $20 fix in to a $1000 fix in a hurry.

[ayton]

Yes, it is. When your engine is below normal operating temperature the ECU leaves the A/F mixture in warm up mode, meaning running rich. Running rich all the time uses up a LOT more fuel, fouls out your O2 sensor and will eventually foul out your cat. Those can turn a $20 fix in to a $1000 fix in a hurry.

exactly.

[Poke2120]

Drove around for 4-5 months with my thermo stuck open, eh money was tight what ya gonna do

Henry

[1995red318i]

my car's doing this too....i should get on it.

so on the m42 engine then you have to remove the fan, but on the m44 you don't?

[blaze]

Yea mine was stuck open a few weeks ago. Happened on my way back from a 300 mile trip.....Needless to say, dont bring it to the dealer to get it fixed. If you can do it yourself, your better off. I didnt have my tools, so I payed....well lets just say raped with no vaseline. I really fathomed just getting a new car cause it was so rediculous for a relatively easy job.....

[bimmer95]

so on the m42 engine then you have to remove the fan, but on the m44 you don't?

Manual gearbox equiped M44s don't have a fan to remove.

[dcardenas]

I was going to take it to an independant shop. How much can I expect to pay?

[captainkarl]

Side Note:
I am about to do this myself tomorrow i think. Where and how do I drain coolant?

[sben]

Well on my m50 there is a little plastic screw under the radiator, similar to the oil pan bolt for draining your oil.

Look it up in Bentley--I imagine it gives model-specific info.

[captainkarl]

How should I dispose of the coolant though?

[NeverLeaned]

Im sorry fellas,

But if you are too lazy OR (more importantly) too poor to change your thermostat, then you shouldn't own a BMW......... Try honda instead

[sben]

How should I dispose of the coolant though?

I drain my coolant into a plastic jug. Then I take it to the nearest Jiffy Lube or whatever, and they dispose of it for me. I believe here in Texas (and most states) lube places are required by law to take coolant and oil from people.

-Ben

[TrunkImpaired]

I drain my coolant into a plastic jug. Then I take it to the nearest Jiffy Lube or whatever, and they dispose of it for me. I believe here in Texas (and most states) lube places are required by law to take coolant and oil from people.

-Ben

I never knew they took it. I may actualy flush out my coolant one of these days. Thanks for the tip.

[ayton]

guys this is a really easy job...I think it took me a total of 30 mins to do it. The hardest part was bleeding the air out. BMW's are harder than other cars at least in my experience. But then again I have only owned german cars. My VW was so easy I just dropped in the coolant and ran it. If you are worried about draining the coolant - I cheated I just popped the top hose and drained the coolant there and the topped it back off after.

[Steve530]

I had a Porsche 944 that was really difficult to bleed. Bleed, drive it, bleed again, drive some more, bleed some more.

BTW, I've read that if the engine doesn't reach operating temparture it will wear more quickly because the engine tolerances are designed at operating temparture.