E34 sal. manual. cooling system leak

[powerfulheart]

Hya! I finally managed to bleed my E34(5.25 1991-1996) After many attempts.The thermostat is now opening-pressure gauge OK,Heaters working-Ticking over nicely.Sadly I have discovered a leak which appears to be coming from the expansion platic tank attached to the side of the radiator.Can I seperate the expansion tank from the radiator or is there anyway of repairing the leak etc-Hope you can help-Powerfulheart

[darkhorse737]

i sorry to hear that... unfortunately, air pockets in bimmers are hard to bleed sometimes. Personally, i squeeze the hoses a few times during the bleedin process. It helps to purge the air out.

Your radiator must have the integrated reservoir. I'm not sure if you can separate radiator from the expansion tank. But the easiest way to know is: call your local dealer and ask if just the expansion reservoir is available as a part. If yes, then there's your answer.

From experience, the leak mostly occurs from the seal of you coolant level sensor(located underneath the reservoir). Have a look-see. It just might be that an o-ring seal is all you need :-)

[burtv]

I had a really hard time bleeding the tank on my 91 525i. When the engine was cool I filled the coolant tank to the cold level mark, removed the bleeder screw (located next to the radiator cap) then removed the upper radiator hose from the radiator leaving the other connected to the thermostat housing. With the help from a friend we then poured coolant into the hose (more than a gallon and probably because the radiator was replaced with a new one and and was completely empty). we kept pouring coolant in there until it was full. Be careful because if you are holding the hose higher than the neck on the radiator, coolant will start coming out at the neck. When full re-connect the hose to the radiator and then start the engine without the radiator cap or bleeder screw in the radiator. Very quickly the coolant will begin to come out of the bleeder screw. At that point I carefully put the bleeder screw back into the radiator and screwed it down tight being careful to not screw in to tight and break it. Then I watched the coolant flow into the recovery tank through the upper hole between the radiator and the coolant tank. I then turned off the engine, let it cool and filled the tank to the proper coolant level. Then with the radiator cap on, start the engine and let it pressurize and reach the proper temperature and then examine for any leaks and your done (unless you have any leaks).