cooling system worries. with some data

[Chriskbmx]

so im having this weird issue with my e30 that is starting to worry me. when i drive my car for an extended period of time(about 15min or more) the needle starts to creep past half way and sometimes the whole way up to the 3/4 mark.
btw the car in question is a 1987 325e. when it idles though the needle seems to go down, but this isn't always the case either, sometimes it will start creeping up. any ideas what it may be? i just ordered an 80degree thermo stat hoping that will fix the problem. any ideas what it might be? i have only had the car for 2 weeks, but i saw that the timing belt was done 30k ago so i assume the pump was done to and the car blows hot air so the cooling system is bleed. ideas?

[Komzorz]

Is it losing any coolant?

If not, I suppose your fan clutch could be bad, although those typically overheat at an idle and cool at speed.

Or, your radiator could be clogged.

[Chriskbmx]

i cant imagine it is the clutch fan but i will check it out in the morning, as far as a cloged rad, idk how that would cause it to just not outright over heat.

[Skunkworks]

Try this, Jack up the front about a foot open the heater valves and bleed the system again.

Take a newspaper and stuff int into the fan at idle, If the fan clutch is bad the fan will stop.

Do you have a shroud in place?

Replace the coolant sensor, They are cheap and are the root of alot of problems

[Chriskbmx]

have a link for the cooling sensor? i will try rebleeding it this weekend when im home though.

[Skunkworks]

www.realoem.com or bmaparts .com

[jlevie]

If the engine temperature climbs when the car is moving at 35mph or faster, the cause won't be solely the fan clutch (though it could be bad). The airflow through the radiator at speed is much greater than what the fan can produce. If the engine only ran hot at idle, the fan clutch would be the first suspect.

A bad thermostat, clogged radiator, or some other restriction of coolant flow are the likely causes of the engine running hot at speed and can cause it to run hot at idle. You should check for air in the cooling system, but I suspect that there is some other problem.

Just because the timing belt was changed 30k ago says nothing about the age of the water pump. The factor schedule calls for a water pump every other timing belt change. But that isn't always done.

[dnguyen1963]

Get an IR thermometer and verify that your engine is actually heating up. I have seen bad SI board/batteries causing the exact symptoms.

[Quinthirty]

There are several fuses that trigger the fan. Check fuses 3, 18, 19 and 20.

[Chriskbmx]

alright thanks everybody, ill go about checking all these things this weekend. what should the car actual temp be at?

[jlevie]

alright thanks everybody, ill go about checking all these things this weekend. what should the car actual temp be at?

That depends on what thermostat is in the engine. If the stock 80C thermostat, the head temperature should be 80C plus/minus a few degrees.

[Chriskbmx]

well im putting another 80degree thermostat in this weekend.

[Chriskbmx]

so i went out and was checking some stuff out and found a few things. i like the car get warm and get a bit past the half way mark on the gauge and this is what i found. rad temp was around 210, top house on thermo housing around 180-190, hose that goes to the bottom of the rad was around 160-170 and the other housing hose was 180-190. i also found that when the car got warm and i shut it off i could move the fan and spin it with no issue. does that mean i have a bad fan clutch?

[dnguyen1963]

The temp looks fine to me. The fan should move with a bit of resistance. I would check for SI board and batteries next. Your batteries might be toasted. Check for leakage and corrosion on the SI board. You might need a replacement.

[Bmwb]

do the newspaper trick for the fan if it stops when fully warmed up and the fans basically on the highest speed its the fan , just replaced thermostat in my e30 due to overheating my thermo... was stuck closed and when i took it out stuck a tourch 2 it ... it would not open and it looks brand new 0_O . also replaced my water pump . mine creeps up at idle but goes down when driveing to cold , heats warm , but sometimes hesitates and turned off on me when it started to creep down when idleing any ideas on that ,