Thermostat

[mikem]

Anyone know what temp the thermostat works at on the E46 M3 ?

[Chaos]

Not 100% sure Mike. I do know that the warning tolerance is 75-110C though, so logic would dictate that the stat would probably open around 90C.

Most people with FI or who run full track cars tend to swap it out for one in the 75-85C range, we've supplied as low as 65C (on a GTR-spec S54) before now though.

[mikem]

Thanks Dan, I can see the temp. guage move from dead centre to slightly cooler and back depending on how I`m driving it, so I thought maybe the thermostat was sticking open slightly.

I put the instrument cluster on test mode today but the water temp is only moving from 83-84 ish to 80-81 ish. If I drive flat out it goes to 87 (slightly beyond vertical) and I can`t get it to go any lower than 79 (just above the first dot of normal) (I can only get 79 by letting the car coast downhill on the motorway for a long time.

I always thought the needle shouldn`t move at all but logic tells me the temp inside the engine can`t be static all the time and a 3-4 degree change doesn`t seem enough to suggest the thermostat is faulty but I can`t understand why the guage has started moving all of a sudden. I also read a topic somewhere that said BMW built a tolerance into the guage (to stop it fluctuating) not to alarm customers by it moving slightly.

[imu]

I always thought the needle shouldn`t move at all but logic tells me the temp inside the engine can`t be static all the time and a 3-4 degree change doesn`t seem enough to suggest the thermostat is faulty but I can`t understand why the guage has started moving all of a sudden. I also read a topic somewhere that said BMW built a tolerance into the guage not to alarm customers by it moving slightly.

Same thing happened to my M3 mate (Pauls phoenix yellow used to do the same, not sure about his SG car tho)

[mikem]

Thats nice to know ............ if its going to break it`ll break in 2 weeks time anyway. :D

Still got 5 mths warranty left (kind of ) :D

[imu]

Thats nice to know ............ if its going to break it`ll break in 2 weeks time anyway. :D

Still got 5 mths warranty left (kind of ) :D


I'm pretty sure it's normal, but like you I only noticed it after having owned the car for 6 months or so, coming back from a Ring trip - maybe thats why it started playing up :D

Warranties are there for a reason... :cool:

[mikem]

Incase anyones looking in the future. The std Thermostat opperates at 80 degrees. So I guess mine is fine.

E39 M5 is 79 degrees.

[Chaos]

Interesting info, always thought it ran a little hotter than that but it's good to know, ta. :) (Also means that the guys changing it out for 75C must either be really precise or they're spending time/money on little gain)

[mikem]

Apparently both these cars are quite low for BMW`s Dan.

I don`t really undestand alot about it but I do know that driving mine flat out only raises the temp by about 4-5degrees compared to sedate driving, so maybe the 5 degrees makes a big difference on track, maybe they don`t have the fans, I know Simpson had removed the one on their demo car.