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1988 560SEL
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13 Posts
Discussion Starter #1
Hi all, my 560 has traveled 330k kms and has a smoking issue that points to the valve stem seals/guides. Only smoking at startup after long idles at the lights on hot days. I am planning to change the valve stem seals, chain, chain tensioner, guides and cam oilers. Because of the smoking issue I'm using 20W60 oil plus Lucas Stop-Leak additive. The car runs fine. Just to make sure that there are no major problems before doing the work I decided to do a compression check, using a quality German "Motometer" compression tester with an upper limit of 12 kg/cm2. With a hot motor and full throttle, all cylinders cause the gauge to bottom out at it's upper limit. I checked the accuracy of the gauge by setting my compressor to different values for comparison. It all checks out OK.

The service manual quotes 8.5 bar to 7.5 bar as upper and lower limits with max fluctuations of 1.5 bar between cylinders. IIRC, bar values and kg/cm2 are almost the same. Should I be concerned or pleased about the high readings on all cylinders? Thank you for your input.
 

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SuperModerator
1986/1990 W126
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13,419 Posts
Isn't the service manual the US market version? If so that may explain it as the US cars are low compression.
 
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