I just got my exhaust housing back from being coated today. I never really looked at it that close before but now I put it together and I think I have a problem. If I spin the turbo with my hand it does not rub but if i push it a little bit while turning it, the exhaust impeller rubs on the housing on one side. You can see in the picture how one side is much closer to the housing than the other. I made sure it was sitting flat and cleaned both sides of where the exhasut and the center section come together. I dont know what to do. Is it ok like this? Like I said it does not rub if I just spin it but it is really close. Any ideas?

Eric

 

No one can help with this?

 

What turbo is it? How much mileage on it/where'd it come from/know if it's been rebuilt before? Who did the coating, what is it, how thick is it?

Beg/borrow/steal (ok, don't steal, forget that part) a dial indicator, with both hot & cold housings off measure how much side to side slop there is, and then measure the end play.

But no, if the internals are in good shape, you shouldn't be able to make either wheel touch the bore of the housings. Unless the coating is too thick.

 

looks like possible coating got to thick on one side are you able to tell if it is cutting to metal of housing or just shaving coating?

 

anyway to get a step back on pic cause looking at the ones you have the second looks like it got very little coating almost like you can still see some metal and then gets very thick on other side which is not uncommon with coating

 

It's a pt-8847, about 3000 miles on it, never been rebuilt, polydyn did the coating, don't know how thick it is. Looks like its just shaving the coating when it touches. I'll get a mic and check it tomorrow. Maybe a mil gauge that body shops use to check the thickness of paint will work to see how thick it is, anyone try that before? It has very little shaft play also.

 

Something else to check - loosen the clamp and rotate the turbine housing. Does the 'tight spot' follow the same spot in the housing? See what I'm getting at?

 

Yeah good idea I'll try that also. Thanks for the help.

 

havre had several exhaust housings coated by poly dyn and all had the same problemits how they hang em. the coating groups more on one side than the other i just take a flapper wheel and knock it down at the spot it is interfering and viola no more problems .

 

So do I knock it down just to where it will no longer touch or does it need a certain amount of clearance? Did you take it back down to the metal?

 

Ok got it fixed. Sanded it down a bit where it was touching but was still really close to touching. So I then sanded the coating off on the part that sits flat on the center section and now it works perfectly. Thanks for the help.

 

Stop pressing on your turbo shaft! When you get your turbo up and running the oil pressure will tighten the shaft so it don't rub!

 

Get yourself a little dremil or rotary burr tool and fine stone bit and grind out the area and also grind out the clamp area until it's back to metal. Sounds dodgey but unless you have a lathe it would be the only way to be sure it won't rub.

 

I would remove any and all coating from the inside of the housing, flanges, and where the center section meets the turbine housing. Ceramic coating can heat up and be released into the turbine wheel.