Helicoil thread repair

[jay44]

Hello everyone,

I bought a fantastic helicoil kit at an absolute bargain to repair my oil sump plug thread that I partially stripped when I overtightened it (amateur move I know) on my last oil change.

I am very conscious of getting any metal swarf in the oil pan when I drill the original hole out and then re-tap the new thread. For the tap, I know I can use grease which will be fine, but the question is can I just tap straight on top of the original thread without drilling and boring out the original thread? I'm very worried about the drilling because the metal fragments will go everywhere.

I don't have the time to drop the pan, so that isn't an option for me I'm afraid, although that would be best of course.

Cheers!

[E-bmw]

jay44 said:

I don't have the time to drop the pan, so that isn't an option for me I'm afraid.

Then you haven't got time to repair it.

Either wait until you have got time, or pay someone who does.

[steveo3002]

the kits are made to fit into the exact size hole...so yeah needs drilling

you could fill the sump once repaired with cheap oil and drain again to flush out any bits...guess it depends if were talking £500 banger or new supercar

[227bhp]

It can't be that fantastic if it didn't come with instructions.

[jay44]

Addressing the query directly:

Completely understand how a new tapping process is meant to occur, I'm just checking if tapping the new thread on top of the original thread is feasible? I've only ever tapped metal on a workbench, after drilling out a hole, and I don't have access to what I need to test it nowadays.

The oil flush is a good idea - I was originally planning on just doing that - I'm just worried about debris.

[jay44]

227bhp said:

It can't be that fantastic if it didn't come with instructions.

Who said it didn't come with instructions, eh?

[GreenV8S]

jay44 said:

the question is can I just tap straight on top of the original thread without drilling and boring out the original thread?

If you're fitting a thread insert you will need to drill and tap. The kit should have come with the correct size drill, or at least instructions about the correct size drill to use.

It's not completely unreasonable to do that in situ - it depends how precious the motor is and how confident you are about clearing the swarf out afterwards.

[RobXjcoupe]

If the thread is stripped then use the correct sized helicoil tap. No need to do any drilling. If working upside down with a greased up tap and clearing the swarf every half turn then I can’t see you getting any swarf into the sump pan.
As mentioned before though, a better job is to remove the sump and be absolutely sure you don’t get any swarf into the sump. To be fair the time you have been pondering, you could have done that by now

[E-bmw]

jay44 said:

I'm just worried about debris.

Then there is only 1 sure-fire solution, do it properly & remove the sump.

[227bhp]

jay44 said:

227bhp said:

It can't be that fantastic if it didn't come with instructions.

Who said it didn't come with instructions, eh?

Then read them, specifically the bit where it states something like 'using the drill bit provided drill the hole'.
You also haven't said what the sump is made from. I'm presuming (as it's stripped) then it's aluminium. If it is then there is no problem with doing it in situ as anything which isn't washed out when you flush it out (which you will be doing won't you?) Will be soft, non damaging and big enough to be caught by the filter.
If it's steel then think again.