I can't get the radiator bled :-(

[bfons]

Guys,

1990 525i (M20)

I am having a heck of a time bleeding the air out of the coolant system. It is driving me nuts. I have done everything I can think of and I still have air in there somewhere.

BTW, I replaced the radiator, water pump, T-stat, and fan clutch.

Any tips?

Brian

[winfred]

m20 525s are a notorious bitch to bleed, drill about a 1/16 hole in the thermostat just inside of where the black rubber o-ring fits and put it in the 12:00 position, that will help it to burp but is not allways enough on that cooling system, i try to burp as much air out as possible before starting it by squeezing the hoses and opening/closing the bleed screw, you can put your finger over the pisser hole inside of the filler neck after you squeez the top hose, let up on the hose then uncover the hole then squeze again in a pumping action, doing this in the proper order will pump the air out and suck the water out of the tank, once you get all of the air out that you can start it up and give it a 2k rpm rev and look for water comming from the pisser hole in the neck, cap it and take a short drive watching the gauge, it should be good

[bfons]

m20 525s are a notorious bitch to bleed, drill about a 1/16 hole in the thermostat just inside of where the black rubber o-ring fits and put it in the 12:00 position, that will help it to burp but is not allways enough on that cooling system, i try to burp as much air out as possible before starting it by squeezing the hoses and opening/closing the bleed screw, you can put your finger over the pisser hole inside of the filler neck after you squeez the top hose, let up on the hose then uncover the hole then squeze again in a pumping action, doing this in the proper order will pump the air out and suck the water out of the tank, once you get all of the air out that you can start it up and give it a 2k rpm rev and look for water comming from the pisser hole in the neck, cap it and take a short drive watching the gauge, it should be good


Thank you for the advise. I was able to finally get the air out by pumping the hoses and letting the air out with my finger. What a PITA but after spending about an hour and a half, I'm finally good to go. Another thing I did and I'm not sure it helped but I had the car up on ramps. A friend recommended this. Anyway, when I did this, it seemed to get easier to get that air out.

Thanks again!

Brian

[uscharalph]

Thank you for the advise. I was able to finally get the air out by pumping the hoses and letting the air out with my finger. What a PITA but after spending about an hour and a half, I'm finally good to go. Another thing I did and I'm not sure it helped but I had the car up on ramps. A friend recommended this. Anyway, when I did this, it seemed to get easier to get that air out.

Thanks again!

Brian
The ramps help and the hole in the thermostat also helps.

[octanejunkie]

Had this problem on a 325 i owned. Kept bleeding and bleeding, and still there was air in it. Took it to several garages and they said there was no problem. But i knew after 20 miles or so it would start to boil.
Sadly this did turn out to be a tiny, tiny blow in the head gasket leaking a very small amount of gas into the coolant. This wasn't detected by several different garages until i went to a beemer specialist. When the old gasket was taken off, you could just see a tiny little scorched mark on it near an exhaust valve. Doh.
Not saying this is the case for you, but you've replaced everything that normally goes faulty. These engines suffer terribly from blocked radiators too if the coolant is not changed on a yearly basis.
If its still not bled after three good goes at it. I would investigate further.

[winfred]

cars with seprate coolent tanks have problems when the small hose or the nipple it's atached to get plugged, i've gotten many cars in that "needed head gaskets" that i fixed in 5 minutes with a drill bit/air hose/piece of wire a lot of them from the dealer and other high end shops in town