snapped exchust stud in the housing

[Rotorzilla]

snapped exhaust stud in the housing. After I converted my Cosmo from 13B to 20B I was tighting up the turbo manifold nut and it just snapped. I drove it around for a couple weeks until I had the time to pull the engine out and try and fix it exhaust stud and LIM leak

Ok pulled the trans out and engine today.

here is the stud that is broken off inside the housing.

I spent 4 hours slowly and carefully drilling a hole in the broken stud. there was about 20mm of stud inside. I picked up a brand new set of ez out stud removers. I put a little pressure on it and moved about a 1/4 turn then.........................

SNAP

then ez out snapped off inside the stud. I tired to get it out but no luck.

The LIM Gasket had a major leak on the rear rotor and was destroyed I have one on order should be here in a few days.


so...... it is the rear housing. I am going to put the engine on the stand and remove the rear iron and housing. I got a spare cosmo 13B engine that bought for parts. I will break it down and use on the rotor housings. so I need to order some inner and outer water o-rings. reuse the apex seals that are in there. I think I will change the bearing in the rear gear and rear main seal. so looks like I will be down for a few more days while order o rings.

 

[mazda speeder]

have you tried welding a bolt on? Good luck with your project hope it works out..

 

[cosmojc]

This seems to be a weakness of the twin turbo 20b - I have previously broken a stud about 6 years ago and it looks like another has broken now. Mr Foox has just had to replace the 3 bottom ones on his car!

So the message is - when building/freshening a motor - change them for new ones!

Kramer

 

[cosmojc]

DAZDA confirms it! All the exhaust studs are made from a special alloy with nuts designed specifically for the job and are one use!

Moral t the story replace both!

Kramer

 

[cosmojc]

And yet a further update on the broken stud issue on 20b's. Dazda and I were helping (that means fetching parts and sweeping up!) with an experienced engine builder. There was a big smile and a little pearl of information. Mazda has made the manifold fit a little to snug on 13bs and particularly 20b's - it happens to 13bs too, but not as often. On a 20b drill the manifold mounting holes out by 1mm on the outside mounting points! Leave the centres as they are. Problem solved with a tad more room for expansion.
Kramer

 

[Rotorzilla]

I was unable to repair the stud, so over the next couple months I will be be doing a full rebuild. I have a set of FD housings I will use that have new studs. with using the FD housings it will have the larger exhaust ports.