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Turbo spin freely?

Should a k27 spin freely when removed from the car? I bought one a long time ago ang just pulled it out. The wheels move easily but will not spin freely...as in keeps going. Does there have to be oil on the gallies to create the proper "bearing" for the wheel to move freely?

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1986 3.2 Carrera
Old 09-05-2010, 04:18 PM
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Mine spins freely.
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Old 09-05-2010, 04:34 PM
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The freelier it spins the better it is, it applies the other way around too.
Old 09-05-2010, 04:48 PM
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Why would it not spin freely? Coking? There is little to no free play.
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Old 09-05-2010, 04:50 PM
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If there was oil in the bushing it probably has thickened up and won't spin very good. You can clean it up and put fresh oil to it and it will do much better I used 90 lbs air to mine and it sounded like a jet engine spooling up.
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Old 09-05-2010, 06:56 PM
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Should spin-freely, but not a good idea to spin it with out oil being feed to the bearing.
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Old 09-05-2010, 07:13 PM
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"spin freely" is subjective. I can blow on my GT35 and it will start to turn - when I shut down the motor, the turbo will continue to spin for 45 seconds (from an idle) - that's spinning freely. I haven't met a K27 that can do that, but it's relative.

Do you suspect a problem?
Old 09-05-2010, 07:58 PM
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Don, I do.
This is a k27 7600 that I bought about 4 years ago from one of the boards infamous past scammers...Michael Minor. I was actually out of the country at the time and had my brother-in-law receive it . I just took it out of the box and looked it over. I realized that the clamps on the cool side are missing and that the wheel doesn't spin freely...it turns easily but not freely.
So, I am looking for the clamps and wondering what I need to do next. The blades look perfect, there is very little play and there is very little oil residue in the cool side....
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Old 09-06-2010, 12:23 PM
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Quote:
Originally Posted by Turboo934 View Post
Should spin-freely, but not a good idea to spin it with out oil being feed to the bearing.
When I was spinning it I was feeding oil to it for sure.
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Old 09-06-2010, 01:46 PM
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a non ball bearing turbo won't keep spinning after you stop twisting it. You say it spins easily, thats all you can expect from a used turbo that has sat for 4 years. But that in itself doesn't mean the turbo is good or bad
Old 09-06-2010, 03:15 PM
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Thanks. I still need to source some clamps for the cool side.
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Old 09-06-2010, 03:30 PM
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I need these clamps.....circled in red......

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Old 09-06-2010, 03:35 PM
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You need those? OMG

You don't need those EXACT pieces - you can make your own out of 6x1mm bolts. I think they are 10mm long. Use steel washers and tighten about 8 ft lbs. This will keep the compressor in place and allow you to adjust the housing.

Good luck.
Old 09-06-2010, 05:18 PM
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Thanks Don. I thought about that. Actually found some...posted in the classifieds and someone came through.
I will get this thing together and try it out this winter. Hopefully it will work and not need rebuilding.
I have been planning this turbo conversion for over 7 years now. I think I'm suffering from analysis paralysis.
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Old 09-06-2010, 05:26 PM
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I don't know guys, but on both my K27 7006 and 7200 turbos (the 7200 I just put new seals and bushings in), and my old 3LDZ I can say that these things spin freely but won't keep spinning on the bench top for any length of time after giving them a good finger tweak. Too much clearence between the shaft and the bushings without the oil pressure and resultant film to float the shaft off the bushing = static friction drag. That's benchtop, but it doesn't mean the turbo is not "spinning freely" when in the car doing it's thing.
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Old 09-06-2010, 08:02 PM
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Slow spinning after a good "finger tweak" is mostly promoted by some kind of internal friction, friction turns into heat... and on and on... you don't want that. Spinning freely is what you want.
Old 09-07-2010, 05:46 PM
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Quote:
Originally Posted by Miguel Antonett View Post
Slow spinning after a good "finger tweak" is mostly promoted by some kind of internal friction, friction turns into heat... and on and on... you don't want that. Spinning freely is what you want.
Well heck...these aren't brand new out of the box turbos after all. Seen some mileage, all of them. One would certainly expect some level of drag, of course. I guess my point is, don't expect to pull your turbo off the car and tweak it, and expect it to just spin away until the cows come home (but then, perhaps I'm wrong and they should)! Guess I need to go down to the shop and time what free spinning really means. I'll do that and report back when I get a free moment.

PS: Sorry, crappy mood this evening but since you guys are there, then it's a free audience to bi_ch at. Thanks, I feel better now.
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Old 09-07-2010, 08:06 PM
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I can chime in here with my four hundred bucks worth having just been down this road. When I got my K27S from UMW, it was "as new.". I am pretty certain that it was not brand new, but freshly rebuilt, and looked brand new to my untrained eye.

Anyhow, I noted immediately that the turbine wheel did not spin as free as the 3DLZ it was replacing. It wasn't rough feeling, but would only turn for 3 or so revolutions with a good snap. The 3DLZ would spin like a bicycle wheel by comparison. I'd never had a fresh turbo in my hands before so figured that some break-in period was required.

The K27 lived on the car for 6 months or 3k miles before I tore the engine down for a rebuild last fall. I noticed at that point that the turbine wheel had not "loosened up" like the 3DLZ, and I also noted some play in the turbine wheel that was worrisome, but in my haste to get the car back on the road I bolted it back up as is.

Fast forward to a few weeks ago, I decided to pull the turbo and sent it off for a rebuild. I had been seeing a smoke puff on startup more frequently than ever before, plus I convinced myself that the "draggy" turbine wheel could be the reason why the turbo could not maintain even 10psi past about 4500rpm on a 3rd gear dyno pull (I've modded this engine to 3.5 liters and enlarged intake ports to 37mm, FYI). I also theorized that a draggy turbine wheel could contribute to what I feel are higher than expected oil temps (its debatable, however whether my temps are higher than normal given my build).

Well, the rebuilder said I could have ran it for a while longer but that it was a good idea to rebuild it now. I got a 360 degree thrust bearing to replace the 270 that was in there. The turbine side shaft bearing was a bit cooked but I've seen worse ones posted in photos on this forum. The rebuilder told me that I shouldn't expect the turbine to freewheel on the bench. When I compared to the 3DLZ he stopped me and said that they have a completely different bearing design.

I looked at dozens of forums (both Porsche and DSM/Supra/RX7) and there is a lot of conflicting info out there.

I can't really evaluate yet whether the rebuilt turbo is performing better than before. Literally within days of installing it I put the car up for a suspension refresh.

Old 09-08-2010, 04:44 AM
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