m50 rad bleeder bolt won't bottom out....

[ryan roopnarine]

i've tried searching the archives, and did not find anyone with a similar issue.

the radiator is a 2 year old behr on a 1992 525i auto that has, at most, 500 miles on it. after removing the screw to flush out the radiator on sunday, i noticed that the screw will get really tight, but then keep rotating, and "pop" up a thread or two, and will keep spinning ad nauseum. i know that the tightening torque is not much, but i am worried about the screw popping out under high temperature conditions and ruining my day. anyone else had this problem? would the brass bleed screw help fix this? i tried both the relatively new screw that came with the radiator, and an older one that i keep in my toolbox, and both do this. the screw, before this incident, would snug up and not spin continuously. i don't really want to screw with the threads on the bleed screw hole because of the relative newness of this radiator. thanks.

[whiskychaser]

Had a similar problem with a 318 a few years ago. The PO had either cross threaded the screw and/or glued it in. It would go in so far then spin. As a temporary measure, I put another washer under the head of the screw so it bit on 'good' threads and tightened up. It held fine until I could fit a new rad. I binned my old rad a couple of months ago or I would have posted you the cover and bleeder. Maybe somebody else has one lying around?

[glen-sj]

i've tried searching the archives, and did not find anyone with a similar issue.

the radiator is a 2 year old behr on a 1992 525i auto that has, at most, 500 miles on it. after removing the screw to flush out the radiator on sunday, i noticed that the screw will get really tight, but then keep rotating, and "pop" up a thread or two, and will keep spinning ad nauseum. i know that the tightening torque is not much, but i am worried about the screw popping out under high temperature conditions and ruining my day. anyone else had this problem? would the brass bleed screw help fix this? i tried both the relatively new screw that came with the radiator, and an older one that i keep in my toolbox, and both do this. the screw, before this incident, would snug up and not spin continuously. i don't really want to screw with the threads on the bleed screw hole because of the relative newness of this radiator. thanks.


There should be an o-ring at the opening. Perhaps you're missing this o-ring therefore is preventing the screw to be snug.

[ScottyWM]

Right, check for the o-ring. And even then, an old o-ring can get very flat. I got a new bleed screw with a new o-ring ($2 total) and was amazed at the difference.

[ryan roopnarine]

i think i'm going to have to go with mr. chaser's suggestion. like i said, the rad is new and the bleed screw o-ring looks pretty fresh and vital. the spare screw had a clapped out o-ring on it, but did the same thing.

[Gene in NC]

IIRC and this is the side tank radiator, the screw is not supposed to bottom out. See Bentley 170-5.5 torque to 18-27 inch lbs.