m42 radiator drain plug

[monty23psk]

recently I am leaking coolant from my drain plug. It is all the way tight and feel if I go tighter, the plastic screen on the plastic tank is going to crack. Is ther an o-ring inside. I know I can get part #9 from this diagram but wondering if anyone knows or has a radiator out of the car they can check for me.

[Ryann]

Yeah, there's an o-ring. You could pull your drain plug out and take it to any auto parts store, they'll have a new replacement. Or you could buy the whole drain plug.

[monty23psk]

Thanks. I also got another response that it has an o-ring also so my next step was to remove it and check it. I do have o-rings and just waiting on my BMW coolant to get here so I can do this. I got this radiator new 5 years ago and I only loosend it to remove the coolant for a flush or when I did the aux fan, so about 4 times in 5 years.

[monty23psk]

Took the drain plug out. Plug is intact and has 2 small orings. One looks like it has expanded versus the other one but still looks ok. Also the bigger oring is the one that goes in first, so its the first one the coollant hits. I also notice coollant is coming out a the side where there is a little plastic square the clips in. Its color is blue like the plug. What is this clip for?

[vpilarrt]

IIRC the blue clip keeps the drain plug from falling totally out when you loosen it. If you want to remove the plug completely you have to pull the clip out. If you're getting leakage at the clip I would think the O-ring closest to the end of the plug is leaking. You can't really tell if a O-ring is bad by just looking at it - it doesn't take much to be bad enough to not seal. I'd replace them both. Also look inside the darin on the radiator and make sure there's no debris or damage there.

[monty23psk]

Thanks. I thought it was to hold it but figured it had another purpose as I had to remove it to remove plug. Everthing looked good inside and after putting it back together and rebleeding the system, its not leaking. Either way I did buy orings and have them ready in case it leaks again.