Sump Plug Stripped

[Neil Duke]

Getting close to the end.Warmed the engine up for an oil change,undo the sump plug,& it is glued in there.It haspreviosly been helicoiled,so,it is past help.What was the original thread?5/8 UNF?Going to machine a bit of ally rod,& weld it in there.Any better sump plugs,& sizes?TIA

[madjack4]

Hi u should be able to get a time sert fitted they normally are large enough to seal past the size of the totally crap helicoils that has been fitted u need to find an engineering co that have the kit to fit one if not find the size and thread of the standard sump plug and get in touch with wurth they will supply u with a kit that can be fitted without removing sump by using grease on the drill and tap to remove the swarf as u are doing it very easy to do drill out with supplied drill bit use the countersink tool to put a recess in hole use the tap in the kit to thread the newly drilled hole screw the timesert insert on the threaded insert tool scew in all the way the tool splays the insert when fully home bingo proper repair and dont ever fit a helicoil they are complete rubbish no matter who fits them

Regards

[Neil Duke]

Thanks,but the sump is off,& cleaned up.Plan to drill,& tap some 1" aluminium rod,5/8 UNC.Bore the sump to take the bar,cut bar to required shape inside the sump,weld it in there.Job done.

[Series1 Stu]

I would caution against welding because the sump is a casting and prone to crack as it cools. Unless you really know what you are doing, and few people do, then you risk making things worse.

An aluminium thread is not a good idea due to the relatively low strength and that is why helicoils are used in situations where multiple insertions/removals are required, such as with a sump plug. The sump left the factory with a helicoil or similar fitted, it is unlikely to be a repair.

There is nothing wrong with a helicoil, the problem lies with people over-tightening the sump plug probably because they haven't spent 50p on a new copper washer.

Maybe use an oversize sump plug and suitable steel helicoil/insert but please do not rely on an aluminium thread because you will probably have all this work to do again.

Regards

[madjack4]

Hi my v12 has no helicoil in its threaded in sump every car with ali sumps are just threaded from new ive had many sump plugs stripped in ali sumps over the years in my repair shop a manufacturer would not rely on a helicoil they are very poor at best as i said just get a timesert put in dont be welding it u are making a small job into a large job and looking for trouble if sump is off u can always ship it to have it done at a engineering shop most good shops stock timesert kits or equivalent

Regards

[Neil Duke]

Welding of aluminium is not a problem,I employ a few welders,& have full workshop facilities,when they are working.I have had more thoughts on this,& decided to make a stainless insert,out of a stainless socket head cap screw,with an outer thread of M20x2.5.This will then be machined to take a sump plug,& fitted in with sleeve,& bush.Hopefully the insert will never move,& the sump plug will not strip the stainless.

[Series1 Stu]

I definitely think you are better off following your new plan. Welding aluminium castings is fraught with trouble.

Good luck Neil.

Regards

[Neil Duke]

My stainless steel insert ,with original size sump plug,which I drilled,& glued in a magnet.

[Neil Duke]

This is a spare insert,just in case I buy an S3 coupe,in red.