Carbon build up and shaft movement

Turbocharger repairs, alternative options and mods

Carbon build up and shaft movement

Postby Harold_Boom » Thu Sep 10, 2020 11:58 pm

Hi all,

I have my exhaust off to drop the oil pan and looking into the turbo it looks like a bit of carbon has built up (intake pipe and plenum had milky oil in them, hopefully just from 30 years of crankcase ventilation).

I don't know much about turbos, could you guys have a look and tell me what you think. https://youtu.be/HG7VC-liMdI

I forgot to show it but it spins freely.

What is the best way to get the carbon off in place? It just needs to last the summer and then I can send it and the injectors to Charlie for a birthday.

Cheers
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Re: Carbon build up and shaft movement

Postby ptremb » Fri Sep 11, 2020 4:41 am

You don't really need to clean the carbon off as it won't affect anything, it is there because the last few rides were to easy, gotta beat on it once in a while to burn off the carbon, but if you do want to clean it out, use a brass bristle brush on the housing external to the turbine wheel, do it dry and a flush of air holding the wheel to keep it from spinning on dry bushings to clear the loose carbon. Leave the turbine wheel alone, it is self cleaning from the heat of the exhaust going through it.
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Re: Carbon build up and shaft movement

Postby longfiredragon » Fri Sep 11, 2020 11:28 am

Yes you can pretty easily clean the carbon off. It is hard to tell from the video but it looks like the turbine wheel has too much side to side play and is hitting the sides of the housing? Like I said it is hard to tell for sure but if it is, this is a problem. If the exhaust side is making contact them most likely so is the compressor side. It can slap, make noise, cause damage to everything and possibly even come apart which as I am sure you can imagine is really bad news.

Make sure it is not hitting the housing at all. Mine has been this way, and I shut her down disassembled and shipped to Charlie. No riding with it making contact on the side walls. Just a suggestion. :victory
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Re: Carbon build up and shaft movement

Postby Harold_Boom » Fri Sep 11, 2020 11:38 am

longfiredragon wrote:Yes you can pretty easily clean the carbon off. It is hard to tell from the video but it looks like the turbine wheel has too much side to side play and is hitting the sides of the housing? Like I said it is hard to tell for sure but if it is, this is a problem. If the exhaust side is making contact them most likely so is the compressor side. It can slap, make noise, cause damage to everything and possibly even come apart which as I am sure you can imagine is really bad news.

Make sure it is not hitting the housing at all. Mine has been this way, and I shut her down disassembled and shipped to Charlie. No riding with it making contact on the side walls. Just a suggestion. :victory


Yeah I was worried about that. If it's not hitting it's damn close. Would there be some kind of scoring on the side of the housing? Like a clean area or some give away that it's touching? I could try get a feeler gauge in there
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Re: Carbon build up and shaft movement

Postby longfiredragon » Fri Sep 11, 2020 11:58 am

Yes, a lot of times there may be some marking on the housing if it has been hitting. You may see scrap marks or clean marks as you say. It's a long story but back when Charlie and I were first looking into the clutch damper issue, (that's what trashed mine) mine actually made noise and you could hear it bouncing off the sides of the housing at idle.

I can't tell you the clearance but Charlie can, which I am sure he will see this post at some point or you can PM him.

If I get this wrong Charlie please correct me. I think there can be a danger in that the turbocharger can spin smoothly most of the time even if it can move enough to maybe make contact with the housing wall. But what happens is that the faster it gets spun up is when it may get out of wack so to speak and then hit the housing. Point here is that it might have enough play to touch but not leave any visible marks on the housing.

Obviously this is the worst thing to happen because now the turbocharger is spinning at max speed and if it contacts the housing it can literally grenade. If this happens, most likely your motor is trashed. All the metal fragments will go through the transfer pipe, plenum, into the throttle bodies and smack right into the motor.
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Re: Carbon build up and shaft movement

Postby Harold_Boom » Fri Sep 11, 2020 12:33 pm

Like a pot hole under full boost, yeah I can image that would be very bad.

Hopefully Charlie gives me the all clear for summer but I will check for any scrape marks tomorrow and put a picture up
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Re: Carbon build up and shaft movement

Postby Charlie @ Evergreen » Fri Sep 11, 2020 1:42 pm

Good input from the LFD and your bearings are very worn. If you get much more damage then parts can not be machined so suggest get it done.
You can see the oil that leaks by the had burned and carboned up one the blades also. So its ready.
Be safe and save it parts are getting thin. Mostly Turbine Wheels.
84' ZX750 Turbo 85'ZX750 Turbo
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Re: Carbon build up and shaft movement

Postby Harold_Boom » Fri Sep 11, 2020 1:50 pm

Well crap, I will PM you Charlie. Thanks
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