Oil sump nut oversized

JAMZILLA321

JAMZILLA321

Regular Member
British Zeds
Joined
Mar 17, 2023
Points
21
Location
Manchester, wythenshawe
My oil sump nut leaks so I would like to know what oversized nut I should buy (the ones that put in new threads) for bmw z3 1999 1.9i UK - any help appreciated
 
There are videos on youtube about various methods of fixing this. All you have to do is google it.


Some advice: Since becoming aware of this issue I have stopped using the oil drain plug and now use an oil siphon to drain the oil. It works fairly well and I avoid the issue altogether.
 
Any decent garage should be able to drill out damaged threads and fit a “Helicoil” supplied with a new sump plug. You can’t just fit an “oversized” plug. We used to do this where I worked before I retired.

Tony.
 
So did I but I never managed to strip a sump plug thread, and didn't use anything but common sense.;)

Tony.
 
I've seen many a home mechanic use an impact driver on car parts that could lead to this issue at the oil pan and other locations.
 
No accounting for Morons though, is there?

Tony.
 
If the bolt tightens properly at the moment.
Then assuming no damage on the sump contact surface then i would buy a brand new genuine sump drain bolt and washer see if it seals.
If it doesn't tighten properly at the moment like @t-tony says Helicoil would be the next way to go .
Because after that its replacement sump.

Stephen.
 
Stevo7682 said:
If the bolt tightens properly at the moment.
Then assuming no damage on the sump contact surface then i would buy a brand new genuine sump drain bolt and washer see if it seals.
If it doesn't tighten properly at the moment like @t-tony says Helicoil would be the next way to go .
Because after that its replacement sump.

Stephen.
Click to expand...
It tightens really weirdly like you can get a decent torque on it but it still leaks - also where can I get this sump nut / what size is it?
 
If it still leaks it must be cross threaded, which means the sealing surface of the plug and the face of the sump are not aligned.

Tony.
 
If cross threaded it may still be possible to retap the thread back to the correct one depending on the damage to the original then i would definitely be using a new plug from the bmw dealer to give best chance of holding.
Stephen.
 
Stevo7682 said:
If cross threaded it may still be possible to retap the thread back to the correct one depending on the damage to the original then i would definitely be using a new plug from the bmw dealer to give best chance of holding.
Stephen.
Click to expand...
It could be cross threaded actually because it fits really weirdly - I will look for a oil sump nut on Amazon 👍
 
Don’t try fitting a new plug till you have cleaned (re tapped) the thread in the sump. Make sure that you can screw the plug all the way in by hand (using just your fingers that is) and wrap some PTFE tape round the plug threads before finally fitting the plug.

Tony.
 
Also, copper washers do encourage overzealous tightening, switch to fiber washers .. nip up tight with nothing bigger than the right sized spanner..;).
 
t-tony said:
So did I but I never managed to strip a sump plug thread, and didn't use anything but common sense.;)

Tony.
Click to expand...
I spent 18 years working for the same firm doing what you might call fleet maintenance. Tightening drain plugs and the like with a torque wrench makes sense if it's me that's going to be sorting out any f**kups when it comes in next time.
 
I worked for myself for 10 years before our Carla died so any cock ups were all mine to sort too. From 1973 to 2018 not one stripped sump bolt, and, I was an apprentice in Agricultural Engineering, a so called "big hammer man!".

Tony.

ps. We used to do Mini head gaskets without a torque Wrench.
 
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