S-Class (W126) 1979-1991: 300 SE, 300 SEL, 380 SE, 380 SEL, 420 SEL, 500 SEL, 560 SEL, 360 SEC, 500 SEC, 580 SEC, 300 SD TURBODIESEL, 300 SDL TURBO, 350 SD TURBO, 350 SDL TURBO

560SEL Running on 7 Cylinders

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Old Jul 1, 2005 | 06:48 PM
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85 yugo
560SEL Running on 7 Cylinders

Hello,
My Bro has a 1991 560 SEL and it seems to be Running On 7 Cylinders. Everytime You start it a Nice Bluish-Black puff of smoke comes out of the Tailpipe. Many mechanics have told him that the #8 Cylinder is not working Properly, and that it has low compression.

Also, about a year ago, he changed Some Computer under the hood. (Not sure what it really Does) and just 1 number was wrong. Could that be the Culprit?
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Old Jul 1, 2005 | 08:21 PM
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1986 560SEL, 97 BMW 740iL
Did he check the spark cable and plug?
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Old Jul 14, 2005 | 08:49 PM
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85 yugo
Yeah. That was Replaced with Bosch stuff.
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Old Jul 14, 2005 | 10:40 PM
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1986 560SEL, 97 BMW 740iL
Then he'd need to take it to a MB spec to look under the valve covers to see if any piston is shot. How about the distubuter unit? No crack or bad wiring?
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Old Dec 3, 2008 | 11:49 PM
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merc 126 500 sec 1984
open up the bosch controll unit on the passanger side wheel arch. should have a green cable going to it, it near the coil. check all solderings very carfulli. i had 7 out and the car would not start. cheap solder fix
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Old Dec 4, 2008 | 08:16 PM
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What is the service history of the car?
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Old Dec 14, 2008 | 08:22 AM
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420 sec
did he fix it ?

i have same problem with a 420 #8 cylinder is not working ignition is new
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