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purplehaze purplehaze is offline
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Join Date: May 2005
Location: Waiting to pass you, or Sebastopol CA
Posts: 349

You're right, your rear valence cuts look good. It lets other drivers also see the goods.

I think it's coking as well. This could have been happening for some time before your rebuild - or just started since. Glad you caught it.

The problem won't be that it collects in your oil tank, rather it will clog the cam spray bars or piston cooling oilers. Then you're looking at another rebuild.

From what I understand, coking doesn't usually occur from just driving to work. It happens after a quick shut down, in a super-hot turbo, that hasn't cooled down sufficiently. Oil just sits in them, boils and turns into the charcoal bits you're showing. it's not the ambient temperature that's the problem, or the temp of the oil overall; it's the oil in the housing that's getting killed.

If you're not already, you want to take 2-5 minutes to cool down before shutting off the key, especially if you've been on boost. More time needed if you raced to work. I track mine, so I take a cool down lap, then let it idle for ~5 minutes before shut down.

Others will chime in hopefully as I'm not familiar with the K27. It's just oil-lubed, right, no oil cooling? For my GT-series I use coolant to aid in keeping the turbos from baking the oil.

I'd suggest checking the oil drain lines from the turbo, to make sure you have good oil flow. Remove, blow them out, clean, etc. If they're too small or restrict the flow, it will allow the oil to just sit there and bakey bakey. Start the car with the return line disconnected to make sure it's returning oil at a healthy rate. That will also allow the turbo to purge the bigger pieces that may not have fit through the oil return line. Messy, but worth it!

I'd also suggest changing your oil like an obsessive compulsive maniac. After my rebuild, I used break in oil and changed it 3 times within the first hour or so of run time. It flushes out all the rebuild materials and allows parts to get to know each other. It's cheap compared to the alternative. In your case, you need to purge your system of all that crud; change oil and filter several times.

I don't know enough about your oil to comment. I use Brad Penn 20/50 Racing and have no issues.

Hope that helps.

Nice car BTW!
87' 930TT
Old 02-21-2009, 04:29 AM
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