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

Carb Legal 1985 500SEL Running Problems

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Old Aug 24, 2016 | 03:04 PM
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Gshep71's Avatar
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From: California
1976 240D, 1985 500SEL
Carb Legal 1985 500SEL Running Problems

Hello,

As the title says, I have a 500SEL with some running problems. At 151,xxx mi, it's been sitting for 4 or 5 years due to a developed running issue. Garaged in the dry desert climate of Southern California. Symptoms like rough idle and stalling at random times while driving point to a vaccum leak, however investigation may prove otherwise.

I have a shortlist of things to go over on labor day weekend, but I wanted to post up here in hopes that a second opinion may guide me directly to the problem. Has anyone else had these issues on the 5.0L engine and have a solution?

Bonus photos for reading this and helping me out. Your input is appreciated! I can't wait to have this thing running like a champ again.









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Old Sep 7, 2016 | 06:41 PM
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Gshep71's Avatar
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1976 240D, 1985 500SEL
Bump, any ideas?
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Old Sep 9, 2016 | 01:07 PM
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jonwhite99's Avatar
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78 450SL, 83 500SEC, 83 280TE, 85 500SEL AMG,85 500SEL Limo, 85 280TE AMG, 94 e320 Wagon, + Others
Ideas?

I would start with

1) Drain the gas tank and put new gas in it.
2) Check the Fuel Pump and change the Fuel Filter
3) Get the injectors checked and cleaned - Replace as need.
4) Check the Fuel distributor and Warm up regulator
5) Then Spark plugs etc.

Good luck
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Old Oct 10, 2016 | 01:08 AM
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E.Brendle's Avatar
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From: Hooksett N.H.
1987 560SEL
​​​​​​Get all the info you can about the Bosch Jetronic injection system. The plenum and pintel adjustment may need to be cleaned and serviced. When this system is working properly and adjusted correctly these cars are phenomenal. Good luck.
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