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Another 930 leakdown question

I have a low miles (36K) 930 that has had engine gone through less than 10K miles ago. I have an issue where 5 of 6 cylinders have leakdowns of 4-8 % and one cylinder is 30 %, leaking out exhaust of #4. Based on a quick search of this topic I put a couple of bottles of techron in car and went for a spirted drive. I will leakdown "bad" cylinder again tomorrow and pull valve cover and do the tapping routine that has previously been reccomended. Best case senario is problem has been resolved, just curious what worst case senario is, motor runs well doesn't smoke or use oil, has excellent oil pressure.
Thanks,
Phil
Old 08-25-2011, 08:31 PM
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All the Techron in the world is not going to fix 30% leakdown #'s.

Sounds like some head work is in your immediate future. Bad valve seat, burnt/cracked exhaust valve, cracked valve guide, or something along those lines......

Mark
Old 08-26-2011, 08:26 AM
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Mark,
I think you are probably right but it doesn't much of carbon deposit to cause leak down issues. I need to go through repair reciepts and see when heads were done last.
Thanks,
Phil
Old 08-26-2011, 09:05 AM
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Hey there Phil,

I would normally agree, but you stated that the engine runs well, burns no oil and has only 10k on it since rebuild. Can't imagine any significant amount of carbon build up could occur during that short of time on the engine, especially on only 1 cylinder.

Although, stranger things have happened...never discount "Murphys Law". You could have a bad injector on that cylinder, making that 1 cylinder run pig rich, which could cause undue carbon build up in a short time frame.

Best of luck with the diagnosis.
Mark
Old 08-26-2011, 10:43 AM
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Can't wait to hear the results...
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Old 08-26-2011, 02:27 PM
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What tune is the engine in? Is it stock or is it running higher HP?
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Old 08-26-2011, 02:46 PM
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the exhaust valve on that cylinder mught be adjusted wrong and hanging open
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Old 08-26-2011, 03:03 PM
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Quote:
Originally Posted by ken911 View Post
the exhaust valve on that cylinder mught be adjusted wrong and hanging open
+1
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Old 08-26-2011, 04:02 PM
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Here are the specifics-
Motor mostly stock, K27 turbo and Euro exhaust, had valves recently adjusted, I thought they sounded loose. Does run a little rich, I live at 4500 ft elevation, maybe CIS mixture needs a little tweaking. Also had plugs replaced yesterday, very sooty, I don't drive car much which I know is wrong in so many ways. I took it out yesterday and ran pretty hard for about 1 hour, leak down on #4 improved to 25% from 30%, still sucks but better. #5 at 3%, which is very good. We'll do some more investigation and report results. I'll go through repair receipts with a fine tooth comb to see what exactly was done when. Thanks for the help and suggestions, keep em coming.
Phil
Old 08-26-2011, 05:07 PM
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Quote:
Originally Posted by Ken911 View Post
the exhaust valve on that cylinder mught be adjusted wrong and hanging open
Agreed.
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Old 08-26-2011, 05:47 PM
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