Cooling Troubles

[Mark-W]

I have bled the system in my car, all was well, all pipes were hot, heaters blowing hot and temp gauge was halfway, let it cool down an tried again. Temp gauge will not go over the blue, heaters blowing hot
Anyone have any ideas what the problem could be?
Cheers

[Rtaylor2208]

Sounds like a stuck thermostat

[Mark-W]

Sure is, thanks man

[Mark-W]

Just changed the thermostat an its still the same, checked to make sure it wasnt dodgy but its fine, anyone have any other ideas?
Would it be an airlock? As soon as the top hose gets warm the heaters start blowing warm, could it be a dodgy gauge or sensor? Although the engine is getting hot.
Ive not done much mechanical stuff so im pretty clueless, any help appreciated

[Jos]

what temperature was the replacement stat? Can you measure the actual engine temperature?

http://www.e30zone.net/e30zonewiki/inde ... ot_Working

[Mark-W]

The gauge is moving, i'll go do that now though, see what happens.
Not sure what the temp replacement stat is or the old one but its doing the same thing, have no way of measuring the engine temp either

[Mark-W]

Also, all was fine before i replaced the water pump the other week, have not driven it since then because the crank sensor gave up the day after, so its probably something i've done or have not done, but i dunno, everything seems to be breaking at the moment

[Mark-W]

Heres a question, a stupid one, but, when your bleeding the system, is it normal for the heaters to blow warm air as soon as the top hose gets warm?

[SGP]

The symptoms seem to indicate a temp sender fault (the brown one) or possibly a dirty harness plug on same. The resistance is supposed to drop as the heat increases, thus sending the needle on the gauge higher.

[Billwill]

When I bought my 318i M40 the temp gauge would not go above about a third.
I removed the thermostat which was marked as "80 deg Centigrade" and replaced it with a Pirate part also marked as 80 degrees....same problem.
I then bought the correct thermostat from BMW for the M40...this was marked at 88 degrees.
This fixed my problem....temp gauge sits nicely just before halfway mark.

I have read, on this forum I believe, that the M40 needs a 88 degree thermostat while the 6 cylinder models take the 80 degree model.

[Mark-W]

The thermostat is definitely 88 degree and working, turns out the one i replaced is working too

I changed the brown sensor about a year ago when i changed the blue one, so doubt thats faulty, and if it was would it work at all?
How would i clean a dirty harness plug? I managed to clean the prong on the sensor with abit of 180, made no difference

Just got the cluster out, the nut on the back is tight

e30wiki says:
"first unplug the cable from the brown plug, and join the two terminals with a piece of wire"
What two terminals?
also
"test by earthing pin 4?" How would i do this, theres nothing in pin 4