Somebody, in the past history of my car, replaced one of the metric studs that hold the downpipe to the RHB5 turbo with a large standard bolt. I am talking about the lower right stud. The hole that this bolt screws into goes all the way through into the inlet of the exhaust side (crossover pipe side). Should this stud hole go all the way through like that?

 

I hope I said that clear enough because it was hard to explain.

I want to know if the lower right stud hole on the turbo's exhaust outlet should go all the way through to the turbo's exhaust inlet.

That means that the stud (or bolt in my case) is holding the inlet exhaust gases from leaking out.

 

Does anybody have a spare RHB5 turbo from an EA82T that they can look at?

 

Is that clearer?

Marck, pict is worth a kiloword sometimes

I think this may answer you question.

I believe this is the bolt/stud you speak of, and it does not pass through into the exhaust passage.

Please tell me if it helps

Many thanks Skip. Thats what I wanted to know. I couldn't take any pics because the turbo is currently hooked back into my car. But I noticed that hole the last time I pulled the turbo.

 

That maybe one of two reasons why my turbo doesn't boost. Maybe if I put some teflon tape around the bolt that might seal it up better or maybe I should start looking for another turbo. Another reason why my turbo doesn't boost maybe because of the exhaust leak in the crossover pipe.

 

I wonder what idiot mechanic put an American bolt into a turbo which calls for a metric stud and drills the hole all the way through to the turbo's exhaust inlet.

Marck, glad it helped, sorry though, I doubt it is causing the problem, teflon tape probably could not stand up to the heat. If the hole was drilled and tapped to the SAE size, it should seal pretty well.

I don't think it is time to look for another turbo because

The leak in the cross over pipe - now that is serious business when making the turbine spool.

The factory pipe is pretty restrictive to begin with and is covered with a heat shield - big leaks are not visible.

As for the - ahem - mechanic, well any port in a storm but...there are limits. If it was a properly sized drill bit wise and threaded properly it could prove satisfactory (many head studs have been fixed this way. He no doubt did not have a "bottom tap".

I'd start looking for another cross over pipe, or have yours repaired.