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5 Posts
Discussion Starter · #1 ·

I reacently bought an e36 m316 compact from 97 with 210k km on the odo.

High temp engine, if ignition is switched off, should the cooling fan be running?

There was issues with the cooling system. The radiator fan was literally melted off the electric motor. Thermostat was stuck, waterpump was a well worn old oem made in plastic, radiator was leaking, the flange on top of motor to radiator was cracked and the system was full of sticky brown goo.

Expected headgasket due to the goo but co test was negative and after flush this has not returned. I believe previous owner used stop leak or similar product.

I flushed the system real good with steamer, changed thermostat, waterpump, radiator, flange ontop of motor, fanswitch, radiator fan, filled with new coolant, bled the system with fan on max heat full blast.
While driving there is no issue, works fine, heater works and changes between warm and cold on request. Temp gauge is optimal temp.

Problem starts when I park.
as soon as I switch engine off the temp goas up and boils over. Pushes all the coolant out from the expansion cap.

what I find strange is the radiator fan only runs at 1 speed. I think it is max speed that kicks in.
I have checked the fuses and relays wich is in perfect working condition.

Long story short.
1. Should the fan speed 1 run constantly during operating temp?
2. Fan kicks in for short bursts but the coolant is at the edge of boiling before it starts.
3. when I park and switch of ignition, should the fan stil be running?
4. If I turn ignition of but switch it back on without the engine start, the fan is running (does not cook if I switch ignition back on and let cooling fan run)

Fun little car to drive, but the cooling system is over sensetive :p

5 Posts
Discussion Starter · #2 ·
Today I tried to bleed it once more. Heres what I did.

1. Jacked up the front with expansion tank elevated.
2. opened bleed screw all the way.
3. opened expansion cap.
4. filled with fresh coolant 50/50 mixed until both bleed screw hole was filled and expansion tank.
5. Screwed on bleed screw about 70%
6. started the car and put fan and heater to max.
7. topped off coolant and regulated the bleeding and could clearly see more bubbles appear.
8. when no visible bubbles in expansion tank and only fluid came from bleed screw I closes it off.
9. pulled gass wire ontop of engine for 10 seconds with 2500-3000 rpm.
10. opened bleed screw and let more air out. Repeated 3 times and no visible air bubbles from bleed screw.
11. closed bleed screw and let system run until operating temp.
12. coolant started rising in expansion tank so I opened bleed screw and more air came out.
13. radiator fan started running in small burst and I topped off with coolant and repeated step 12.
14. no more air bubbles from bleed screw nor the expansion tank.
15. let system run with closed off bleed screw and cap. Runs with no issues and heater is blowing very hot air.
16. test drive. Drove for good 15 mins with both high and low speeds and rpms.
17. parked the car, switched off engine and switched ignition back on, radiator fan starts running and I clearly see level in expansion tank rising. When fan switches on the level sink and it seems normal.
18. another test drive and this time I did not switch ignition back on after turning off the engine and it flods.

Any ideas? Should radiator fan be idling when ignition is off?

5 Posts
Discussion Starter · #3 ·
Late update.

Radiator fan should not be running when ignition off. There is 2 circuits, 1 going from +15 and other from +30. both are connected trough +15 circuit.

So far I have tested alot and more.

parts changed
Radiator fan
Radiator fan switch
Flanges on the engine

after furthertesting with Co tester I have a very minor detektion.
head gasket is ordered with profile gaskets for timing chain housing.

hopefully this resolves the overpreassure problem.

I have no issues of it overheating when standstill on idle
I can drive for 15 min drives before it cooks
I believe the problem is between chain housing gasket ( the one closest to the head at bottom) and the head gasket itself. It have partly blown out on the exhaust side of the engine and now leaking oil.

Will update post when head gasket is changed.
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