engine temp e30 m3

[tobias]

hi guys i was wondering if anyone can help.

my m3 gets up to temp really quick (probably about 3-5 miles). it then sits between half to three quarter on the temp gauge.

it by no means overheatsbut i have a feeling it shouldnt be getting that warm so quick??

any comments welcome

regards toby

[maxfield]

No it doesn't warm up as quick as that on ym dads m3

[stuartgallafant]

air lock in the cooling system perhaps?

knackered thermostat?

[tobias]

no air in cooling system but thermostat was next port of call. just wanted some opinions first?

i think thermostat is about £60+vat at bmw

[maxfield]

Cheaper here (clicky)

[herman]

Make sure your electric fan has not gone, when I bought my M3 that warmed up quick. Then when I was stuck in traffic it overheated. When your moving its OK.
Be very carefull
I had to have a new one and German and Swedish, don't do them.

Had to be BMW, £180 I think 2 years ago.

[tobias]

hey herman whats the best way of testing the fan

sorry im no mechanic

[tobias]

Cheaper here (clicky)

cheers maxfield

[herman]

When you have stopped the fan should start as there is no air flow. Do that but keep an eye on the temp gauge if it does not kick in switch off.

[Brianmoooore]

3-5 miles is plenty of time for a BMW to be up to temp, and between half and three quarters is within spec on the gauge, although higher than most E30s normally sit.
Does the reading stay constant when it's up to temp?
In view of the price of a new stat, it might be worth getting an accurate temp reading from an external gauge, and/or inspecting the stat to see if there is anything obviously wrong.

[m3-cab]

Mine seems to creep upto just below three quarters but then it just sits there. I suspect it might be the thermostatis switch kicking in the fan too late. As for warm up time, I'd say mine takes about the same amount of time to get to that temperature.

[Brianmoooore]

Electric fan should be irrelevant when you are moving at any speed, especially in Manchester at this time of year.
Engine temp is set solely by the water thermostat. The electric fans job is to help keep the radiator water below that temp.

[herman]

I was in Devon at the time and its just a visual check to make sure the fan is working then you can move on to other causes.

[tobias]

will have a look at both fan and stat for problems. mine gets up to three quarter mark and just stays there. was just a little concerned incase it shouldnt be that high or indeed up to that temp as fast as it is

[Demlotcrew]

Totally normal, mines heats up after only after a few miles also.

But if you note the temp of the oil that takes quite some time to get upto 80 deg.

All M3's i have worked on have had the needle sitting a few mil under the half way mark and in traffic on the half way mark or a little over.

HTH

A failed thermostat will cause the engine to run cold (on the quarter mark or lower)

I think you should have a look at the rad, make sure theres no leaves/dirt/missing veins.

Andrew

[tobias]

hi andrew, mine sits just under 3/4 all the time. but you say a failed thermostat will make engine run cold. is there maybe a switch that may have gone or a sensor??

[Brianmoooore]

Rad problem will make the car hotter when it is worked harder. Stats usually fail part open but not always.
If the temp is stable, but high, then it must be the stat or the gauge telling lies.

[tobias]

but brian have you heard andrews theory of the failed stat would make the engine run cold??

[Demlotcrew]

Stats usually fail part open but not always.

That would mean that the temp will also rise with 'load' on the engine.

I would just make sure the temp gauge is showing the correct temp.

Does your slow speed on the fan work?

Andrew

[tobias]

not sure how to check andrew?

[Demlotcrew]

Is the fan really noisy or just a whisper?

Andrew

[tobias]

the engine fan isnt excessively noisy

[Demlotcrew]

next test involves pulling out fuses

[tobias]

so what is it im looking to acheive???

[Demlotcrew]

To turn the slow speed off by pulling the 15 amp fuse, then forcing the fan to kick in on the 'full' speed.

Fuse 3 for the slow speed
Fuse 18 for the high speed

Andrew

[tobias]

and in doing so proves what? that the fan works on each speed? therfore the stat is the problem??

[Brianmoooore]

Stat failed part open will make the engine run excessively cool when not under load, possibly rising to normal or above normal temp under load, depending on exactly how it has failed. The important thing is that a failed stat will give variable temps.
You need to determine if the car really is running too hot, or if it's just a gauge problem.