Any ideas anyone car is running fine when driving soon as I turn it off the...

Any ideas anyone, car is running fine when driving, soon as I turn it off the coolant level rises and starts coming out of the cap :(

Just changed the coolant on it

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  • Try to bleed it properly. Put car front uphill and use that screew on thermostat housing. It is always very tricky to bleed bmw ;)

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  • Bleed it in the morning, when the engine is still cold...no need to sell the car for the gasket. Just get a new gasket instead...and have the head checked for warping and so a pressure test on it.

  • If yours is M30B30 i can sell you full gasket set i still have it from my project which didnt ended up well, took head of and spoted cracked block.

    But yes do it when it is cold engine. If any help dont hesitate and ask.

  • I have had the same issue with my m30 and it was the new not original cap that wasn't tight. Used the old one and my problems disappeared!

  • It doesn't have a thermo bleed screw, and it's an m70 V12, gaskets on that is way behind my skills/ budget

  • Nice car you got. Try using older cap might be new one thats bad

  • I had a cracked expansion tank and a lot of water was coming out of the cap and bottom of the tank, I changed the cap, tank, coolant, thermostat and it's doing this :( also fitted an electric fan for when it's sat

  • My M70 did the same when the fan clutch was worn. With circulation it barely managed to keep from boiling, and as soon as I turned it off it puked coolant. I solved it by filing down the length of the regulating pin of the fan clutch. That made the clutch engage sooner and keeping the engine cooler at low speed

  • Interesting Stian, I've fitted an electric fan which I've had running. Even with your fan clutch mod surely it still is not being cooled once you switch off?

    It runs fine until it's turned off and the coolant rises up

  • If your fan was running before you shut the engine off, you probably have a different problem. Maybe your thermostat is too hot or the circulating pump is bad and keeping it from bleeding properly.

  • Joe, since you've got an M70, which does not have bleed pin on the thermostat housing, try the other way:

    - Start the cold engine with the coolant tank open. When engine i getting to the normal operating temperature, the thermostat starts to open, and at that point you need to start revving up around 2000rpm. With the cap opened you would be able to see the bleed hose bleeding some coolant + bubbles inside the tank. You need to get to the point when there are no bubbles coming out of the hose - just pure coolant. Then you're ready to go.

    PS This needs to be done when car is DOWNHILL since the coolant tank is on the rear of the engine.

  • Сто Ян thanks! When you say bleed hose do you mean the hose at the bottom of the tank?

  • No Joe, on the top of the tank, bellow the cap there are two hoses going in - one is the bleed for the extra coolant, the other one is for getting out the air from the radiator.

  • Сто Ян I will try and spot the bubbles from the air bleed hose. At the moment it only seems to be rising once I've turned the car off, very confusing. Must have air somewhere! Hopefully head gaskets are good, still pulls like a train

  • I'm pretty sure all is good, except there is some air in the system.

    Forgot to mention - VERY IMPORTANT - when bleeding the air from the system, turn the IHKA to max hot, in order to get the air from it as well.

    This must turn it's electric pump on, and would help much.

  • This should not happen. Can you see where the leak is coming from? Are you sure the two o-rings are in working order and this expansion tank is functional. If the head gasket would be blown, you would get heating problems with engine running and cold air from your inside heating(blower motor). I'm not eliminating that you could have headgasket issues but i doubt it since the engine works fine running.

  • I let it 'bleed' as described above for a while last night. The cars temp stayed normal but when I turned it off the coolant erupted out, made a right mess. Booked into a specialist BMW garage on thursday

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  • Maybe the have a vaccum-pump..?