Okay, so I finally went ahead and removed the OMP last week and have made a bigger problem than I had to start with. After plugging the oil nozzles with the supplied plugs I went to bolt down the block off plate for the actual OMP only to find the top bolt never tightened up. It seems the threads inside the front cover are gone but the bolt is fine.

I'm looking to get this fixed asap but don't know if i should try to use a helacoil or just tap it to a larger bolt size. For right now I reassembled with some threadlocker but I don't trust it at all, good enough to sit in the garage but not to drive.

Can anyone confirm the stock bolt size/pitch for a S4 OMP mounting bolt?

I found a reference to them being 10 x 1.25 but would like to confirm before buying a thread repair kit. The link below doesn't specify the series...

https://www.rx7club.com/2nd-gen-archive-72/master-list-thread-sizes-2nd-gen-nuts-bolts-367392/

Any other way to fix this or advice would be greatly appreciated.

Thanks in advance!

 

I'd helicoil it personally, but you can fix threads with jbweld in a pinch.

Sorry no idea of the bolt size. I'd just pop one of the others out and take it with you to the parts store.

 

Cut a piece of thin soft copper wire and place it in the hole and then tighten the bolt. Used it many times and works well. Size of copper I'm guessing, might be around .060" (1/16") or slightly larger, but it must be soft copper.

 

No way those are 10mm bolts.

Looking at my S5, the OMP bolts have 10mm heads...which makes them 6mm bolts (cause that's how metric stuff works!).
Those bolts are almost certainly 6mm x 1.00.

 

I have a thread gauge somewhere in the toolbox I can dig out too. Okay I'm going to try to fix it one way or another this weekend.

Thanks for the all the replies fellas!

 

Okay so it's M6x1.0.

Used a thread repair kit from the auto parts store that came with the drill bit, tap, tool and coil inserts.

Some pics for reference:

Tools


No pics of drilling the damaged threads but you know what a drilling a hole looks like.

Tapping



Inserting Coil


Repaired Threads


Finished Block Off Kit