Thread: Helicoil Size - TD5 exhaust stud hole threaded

G'day all!

A squeal a couple of weeks ago had me looking, and I found the lower rear nut on the stud on the exhaust manifold was loose... actually nearly falling off.

I gently tightened it up, test drive revealed the squeal was gone.

A couple of days ago, the squeal started to come back, so this afternoon I had another look.

The nut was loose again, so I VERY gently tightened it... except it never tightened, and pulled the thread out of the head instead.

So my plan is to helicoil. The manifold will come off and be checked for true, and it still has the webbing, which will come off - or at least sliced through with the grinder to allow for some movement. I've read to also enlarge the end holes in the manifold to allow for expansion as well.

The engine has been chipped and aftermarket intercooled by a previous owner, and has done about 120K kms, so it's due, I suppose.

I've never used a helicoil, but familiar with the concept, and watched videos of it being done.

My question is what size/kit helicoil should I get?

I'll check the rest of the studs while I'm there. Any recommendations on replacing them all while I'm there, or should I be okay to re-use any that come out okay and look fine?

Cheers!
Michael.

Thanks... it looks as if 8mm is the winner.

Actually picking up a "measuring stick", confirms as 8mm, coarse (1.25mm) pitch (so M8x1.25) - Helicoil do a kit that has 12 inserts in it, so will be handy to have should any more present any problems.

Thanks!
Michael.