Bearing coke.
11-04-2010, 10:45 AM
#3
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Really only a problem if your turbo coolant pump isnt working. It doesnt happen in main or rod bearings, only in turbocharger bearings (on any car). If you drive the car hard then park and shut down without a bit of cooling down, the turbocharger is still very hot and oil can coke on the bearing. Eventually shortens the turbo life. If you drive normally before parking, its fine. And its fine if the turbo coolant pump works properly.
11-04-2010, 10:52 AM
#5
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11-04-2010, 11:51 AM
#6
11-04-2010, 07:43 PM
#7
My turbo coolant pump has not been working for the last 1000 miles, but the car has not been driven very hard. Most of the time I would drive very slow the last few miles before parking and let the engine idle a minute before shutting it off. The coolant pump is now working, and the turbo seems fine but I just want to get a good idea of how easily cooked, er coked a 951 turbocharger is.
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11-05-2010, 12:11 AM
#8
Team Owner
Side note: Porsche / Audi learned that lesson on the first Audi 5000 Turbos in early 80's. NO water jacket, "turbo timer" as the kids call them or shut down reservoir. They had a factory program to change out all the turbos under warranty since so many were locking up (coked). Dealers had boxes of dozens of K26 turbos since seems not too many folks seemed to know they were rebuild-able easily. How do I know this? MY buddy was parts man at a dealer and after parts checked off was to "dispose" of them. Yes, at one time I had about three dozen K26 sitting around. When I started on my 951 a couple of years ago mentioned this to a re-builder or two. Seems the world had a shortage of rebuild able hot sections this size. NO, I couldn't find any after 20+ years.
11-05-2010, 01:09 AM
#9
Race Car
You ride a turbo hard, and put it away wet, the oil in it burns, or "cokes" up from the heat that stays in teh housing. That stuff would score the bearings, and you'd start burning a lot of oil. The water pump Porsche put on has to do a world of good. Early Ford 2.3 turbos were really bad for two reasons - the early ones were oil cooled only, and the oil feed line had a bracket holding it in place that was bolted to the exhaust manifold.
It is easily avoided by idling the car for 20-30 seconds before shut down, or by just taking it easy for a while before you turn off the car. As mentioned, the 951's water pump does a lot of good to help prevent it.
It is easily avoided by idling the car for 20-30 seconds before shut down, or by just taking it easy for a while before you turn off the car. As mentioned, the 951's water pump does a lot of good to help prevent it.
11-05-2010, 09:50 PM
#10
Rennlist Member
No worries on having driven the car 1k street miles without the waterpump. My wp was nonfunctional when I bought my car at 110k miles. I replaced it and am now up to 150k on the original turbo.
11-06-2010, 11:04 AM
#14
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