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View Full Version : BMW 318i temp needle not moving.

carl0s
04-06-08, 08:42
We had loads of air in the system. Heaters not working right. Sorted that out, bled it etc and heaters work nicely now.
Car seems fine, but the temperature needle rarely moves above zero.

What's a likely cause? Still some air in the system around the sensor? Or do these coolant temp sensors die if they're not submerged in coolant?

It's a 1995 e36, M43 engine I think. I'd love to know how to tell if it's an M42 or M43.
monkey3
04-06-08, 08:47
Thermostat could be stuck open or not there.

The M42 engine was in the late e30s and early e36s I believe, so it's more likely it'll be the later engine... but don't quote me on that.
carl0s
04-06-08, 08:59
How do I get to the thermostat? I have looked at changing the water pump, but with the rad cap off I noticed that when I revved the engine the coolant came gushing out of the bleed hole like a massive fountain. This suggests to me that the water pump is OK. What do you reckon?

Is the thermostat located around the water pump. i.e. belts off to get to it?
AshBhp
04-06-08, 09:04
Check connection to temp sensor.
carl0s
04-06-08, 09:05
That's a good idea. I think I know where the temp sensor is. The one to the needle on the dash (the iffy one) is separate to the one used by the ECU apparently.

The difficulty with these cars is that there are so many different engines! With the Supra you can find a good writeup by someone and it's gonna be the same engine!

The best I have found is realoem.com for an EPC like thing, but it's not easy going off those diagrams to find things :(
AshBhp
04-06-08, 09:13
I think it's the left sensor with wire

http://www.zeebuck.com/bimmers/tech/Megasquirt/pics/sensorneck01.JPG
monkey3
04-06-08, 09:15
This happened to me... mine used to overheat so I took the thermostat out and it never overheated again, but then it also never got up to a good temp.

On the m42 engine, the thermostat is located behind the pipe elbow that comes off the front of the head at 90 degrees towards the passenger side iirc.

You can take that pipe off without taking much more off, but it's awkward.
Also, if you do take it off, be careful when you put it back on as I managed to snap a bolt off in the head (those bolts are very fragile it would seem).

I can take a picture tonight of the pipe I mean, unless you happen to have a picture of the front of the engine to hand.
monkey3
04-06-08, 09:17
I think it's the left sensor with wire

http://www.zeebuck.com/bimmers/tech/Megasquirt/pics/sensorneck01.JPG

Well, if yours looks like that, I'm fairly certain it's not the m42.
carl0s
04-06-08, 09:34
This happened to me... mine used to overheat so I took the thermostat out and it never overheated again, but then it also never got up to a good temp.

On the m42 engine, the thermostat is located behind the pipe elbow that comes off the front of the head at 90 degrees towards the passenger side iirc.

You can take that pipe off without taking much more off, but it's awkward.
Also, if you do take it off, be careful when you put it back on as I managed to snap a bolt off in the head (those bolts are very fragile it would seem).

I can take a picture tonight of the pipe I mean, unless you happen to have a picture of the front of the engine to hand.

Amanda has gone to work in the car, but a photo would be great if you get chance.
carl0s
04-06-08, 09:35
I think it's the left sensor with wire

http://www.zeebuck.com/bimmers/tech/Megasquirt/pics/sensorneck01.JPG

Thanks for pic. I'm not sure where that is on the engine but I'll have a look when the missus comes home from work.
carl0s
04-06-08, 09:38
I think it's the left sensor with wire

http://www.zeebuck.com/bimmers/tech/Megasquirt/pics/sensorneck01.JPG

That pic is from a 2002. Whatever one of those is. Looks like an old car.
monkey3
04-06-08, 09:41
that is ancient...
http://images.google.co.uk/images?sourceid=navclient&hl=en-GB&ie=UTF-8&rls=GGLJ,GGLJ:2006-25,GGLJ:en-GB&q=bmw%202002&um=1&sa=N&tab=wi

or is it a 2002 model?
carl0s
04-06-08, 10:03
that is ancient...
http://images.google.co.uk/images?sourceid=navclient&hl=en-GB&ie=UTF-8&rls=GGLJ,GGLJ:2006-25,GGLJ:en-GB&q=bmw%202002&um=1&sa=N&tab=wi

or is it a 2002 model?

No, it's one of those in the google images.
monkey3
04-06-08, 10:09
It's a 1995 e36, M43 engine I think. I'd love to know how to tell if it's an M42 or M43.

http://www.madabout-kitcars.com/kitcar/kb.php?aid=225

Fairly certain that would be an M43 then...

It might still be the thermostat though, or the temp sensor.
carl0s
04-06-08, 10:17
http://www.madabout-kitcars.com/kitcar/kb.php?aid=225

Fairly certain that would be an M43 then...

It might still be the thermostat though, or the temp sensor.

Yeah. According to that, it would have to be an M43. If the car was a 318is then it might be an M42, but it's just a plain 318i so I think M43 is right.