Thread: Exhaust manifold whistle

If the stud has stretched be careful torquing the nut back on as you may end up snapping the stud. (worst case you'd need an easy out to remove whats in the head)

Fairly certain they're a standard M8 thread

I had my studs bored out to M10 when I got some other work done on the head as a fix for the common manifold problems. Not sure how cognisant of the vehicles history you are.

I have lots of mods which bring my exhaust temp up to 750C on occasions.

So far after about 5000K my manifold is straight with no whistles and full boost 20PSI.

I did the following- de webbed the manifold, had it milled straight, ovalled the end holes most at the ends and reducing towards the middle, ceramic coated the manifold inside and out, and used Mercedes Benz studs which are available on Ebay with Bellville washers and copper coated nuts.
Seems a lot to do, but if you have mods, will hopefully help with reliability.
Regards Philip A

I had lost my rear nut too. No whistle, but I did have a black residue. I didn't realise they fall off, I just assumed someone forgot to put it back on.

I put on another nut months ago and it has sealed it up.

Thanks team

Standard M8 x1.25. Bet it breaks though. Much easier to get it out BEFORE it breaks. Ask me how I know...

Remove your exhaust manifold, have the face skimmed back to flat, reinstall. I'd recommend replacing studs and nuts while doing it. If it's leaking and lost nuts then it's already warped.

Originally Posted by twr7cx

Remove your exhaust manifold, have the face skimmed back to flat, reinstall. I'd recommend replacing studs and nuts while doing it. If it's leaking and lost nuts then it's already warped.

Ceramic coat it at the same time.