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1999 bmw 540i bleeding screw

1016 Views 5 Replies 4 Participants Last post by  bluebee
Hi everyone, I have a 99 BMW 540i, I added more coolant and did a bleeding because the low coolant light came on. So I noticed the bleeding screw goes all way down but will not tight hard, but not leaking, I bought a new bleeding screw, same thing it goes all way down but if you keep screwing it keeps turning but not too loose . The coolant tank is less than a month so new. I wonder if that is way it is supposed to be or I want to know if it should be screwed tight like any other screw, Any help is welcome
Thanks
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Seems either the screw or the tank threads may be stripped. While these screws should not be overtightened, they do tightened down after about 3 to 4 full turns.

While you said screw and tank are new, I would double check them, as tank quality is questionable these days even Behr tanks.

BTW, you did not mention what brand your 1 month old tank is, Behr or aftermarket.
Hi everyone, I have a 99 BMW 540i, I added more coolant and did a bleeding because the low coolant light came on. So I noticed the bleeding screw goes all way down but will not tight hard, but not leaking, I bought a new bleeding screw, same thing it goes all way down but if you keep screwing it keeps turning but not too loose . The coolant tank is less than a month so new. I wonder if that is way it is supposed to be or I want to know if it should be screwed tight like any other screw, Any help is welcome
Thanks
It's plastic and threads into plastic. There is an o ring that does the sealing.
If it won't tighten the threads are probably stripped.
You only need to turn it until the o ring touches and then turn it another 1/2 turn.
ok, thank you, I am putting back the old coolant tank I have in hands, the new one is doorman probably raggedy.
I appreciate your help
Yes the new coolant is doorman made, may I need put the old one back on since the car has 118,000 mi I should be fine.
Thanks a lot
See this for details:
- How not to bleed your E39 cooling system (1) (broken bleeder screw)
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