M40 Temperature gauge stays just below halfway...

[georgiev]

Hi guys,

Been trying to figure this one out for a while, but can't get to the bottom of it. The temperature gauge in my e30 318i vert (M40 engine) stays just below the midway (center white line).



I have recently changed the thermostat and the fan clutch because the car was running hot before that. Now it stays cool, but the gauge never goes all the way to the middle. It stays below the center. When the engine is hot and I switch the ignition off the gauge goes up to the center point and down again once I turn it on again and start driving again. So the gauge itself seems to work fine.

Also the cooling system is bled and the coolant is at the correct level. The thermostat is also the correct 88 degree part.

This person seems to have the same problem, but no write up of a solution! http://forums.eurocca.net/showthread.ph ... emp-sensor

So any suggestions on what might be causing this are very welcome.

Anton

[TPS]

That looks normal to me, it should sit on the position

[jmc330i]

Anywhere between the middle white lines is fine I've been told. There's not a massive temp difference between the lines, so you only need worry if its above or below them.

Both my M40 and M20 sit just above the first white line.

[georgiev]

that sounds reassuring. I guess I'm used to my e46 and e53 which always stayed smack in the middle.

[BenHar]

What thermostat did you fit?

The M40 should have an 88 degree thermostat which normally makes the gauge sit in the middle.
The M20 should have an 80 degree thermostat which normally makes the gauge sit about where yours is.

Ben

[georgiev]

M40 ... I used a 88CEL from Mayle

[Billwill]

What BenHar said...I had exactly this problem on my M40...finally got it fixed by fitting a genuine OEM 88 Deg thermostat from the BMW dealers....pirate part did not work.

But I think your needle is not too far out....mine sits only slightly higher than yours and I live in a hot climate.

[jimbom30cab]

my 318i vert temp dial pointed the same also. Infact iirc my e30 318i i had back in '95 was the same.

[georgiev]

thanks for all the info guys. I will let it be for now since it seems to be a minor difference in oem vs patent part accuracy. Good thing is the patent part isn't running hot:)

[bmw335icoupe]

mine m40b18 looks identical, I have also changed the thermostat and the fan. The only thing left is to change the water temp sensor.