Radiator drain plug

MarkAP68 · Post by **MarkAP68** » Sun 10 May, 2015 11:57

I have sprung a leak at the drain plug on the radiator (1.9 M44) after replacing the thermostat & coolant and want to replace the drain plug but there are so many listed on the internet (ones with crush washers and ones without) and not sure which one to get.

At the moment it is a blue plastic one...can any one advise which one I need as didn't want to drain it off to remove it before getting a new one?

Mike Fishwick · Post by **Mike Fishwick** » Sun 10 May, 2015 12:34

It is probably just a damaged 'O' ring, but it may be a split in the drain plug boss. My 2.8 uses a blue radiator plug, but a 1.9 uses a different header tank, so that is not a good guide. Why not just drain the radiator - when it is cold the engine will not be drained at the same time, so a normal bucket will be fine. You can look at the drain plug and 'O' ring, and check the boss for splittting. If OK, buy a new ring and put the old coolant back in afterwards.

For the amount you will save, why bother messing around with Ebay? Just go to a dealer and get the correct plug over the counter.

Vince70 · Post by **Vince70** » Mon 11 May, 2015 10:20

I found that the price of new parts on eBay are normally twice the price than buying off your local BMW dealer when it comes to trim clips and all those small little plastic and rubber bits and pieces..

My local dealer does a free delivery service (chandlers BMW) or if it's just a small clip etc will just put it in the post for me for the cost of a stamp.

I normally just find the part number using this site http://bmwfans.info/parts-catalog and then quote the part number to the spares department who cross reference it for me.. Plus you've got a nice little BMW receipt to put with your bills and you know you've got a better quality genuine part.

Fender2004 · Post by **Fender2004** » Mon 11 May, 2015 11:48

I agree some small parts can be cheaper off the dealer than ebay.
I bought a new drain plug for my radiator off the dealer and it was only about 5 or 6 pounds.

Del · Post by **Del** » Mon 11 May, 2015 11:49

I recommend caution when replacing the blue plastic drain plug. I serviced my whole cooling system last year (all O-rings, bleed screw, drain plug, w-pump & tensioner). I bought a new drain plug from my local BMW dealer and unbelievably it leaked because the o-ring fitted to it was slightly thinner than the old one. In the circumstances, I would recommend just getting a new o-ring (costing a few pence) from your local motor accessory shop.

MarkAP68 · Post by **MarkAP68** » Mon 11 May, 2015 17:21

Thanks for all the replies, I will drain it off and have a look at the weekend

Southernboy · Post by **Southernboy** » Tue 12 May, 2015 07:14

I replaced my OEM plastic plug with a stainless steel bolt and fitted a new seal washer at the time.

MarkAP68 · Post by **MarkAP68** » Sat 16 May, 2015 08:47

Had a look this morning and its not coming from the drain plug.

When the car is cold there is no leak but once its up to temperature it is coming out of the bottom of the expansion tank which is annoying as I didn't have a leak there before I changed the coolant and didn't disturb it as drained it off via the blue drain plug in the radiator.

Would a new rubber gasket be all that is required? or a new expansion tank?

Mike Fishwick · Post by **Mike Fishwick** » Sat 16 May, 2015 09:40

'Would a new rubber gasket be all that is required? or a new expansion tank?'

It depends on where the leak is coming from - a leaking seal or a split header tank. We do not have second sight! Sooner or later you have to look closely and use your judgement, as fault diagnosis by internet forum is at best inconclusive, and at worst expensive.

Perhaps your coolant was under-strength, which would mask a small leak - a proper 50% mix is thinner than water, and will show any small leakage point.

Del · Post by **Del** » Sat 16 May, 2015 11:25

I know a lot talk about replacing the expansion tank but when I stripped my (M44) coolant system last year, I thought the OEM expansion tank was extremely tough and thick plastic and so I just released the clamp after which it just pulls away from the radiator (needs to be removed from car). There are two O-rings which MIGHT just be the problem - a large and small one (as well as the small O-rings on the bleed screw and blue drain plug) - you need to look at REALOEM for the parts - just a couple of quid from BMW.

MarkAP68 · Post by **MarkAP68** » Sat 16 May, 2015 17:50

I have spent 4 hours today replacing the expansion tank!

I had to remove the radiator and cut up the expansion tank to get it out as it was completely seized in place, new one fitted and ran up to temperature...so far no leaks

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Radiator drain plug

Radiator drain plug

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Re: Radiator drain plug