M-Class (W163) 1998-2005: ML 230, ML 320, ML 350, ML 400 CDI, ML 430, ML 500, ML 270 CDI

oh oh i think did something wrong

Old 05-20-2019, 12:19 PM
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1999 ml 430
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hello everyone im a new member, ive always owned a Mercedes, 300ce models only, but yesterday bought a 1999 ML 430. like an idiot i washed the engine bay as it was really disgusting, when i re started it runs very rough and check engine light came on, please help this old fool figure out what i can do, im totally lost on these newer models
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Old 05-20-2019, 04:59 PM
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2003 MB C240. 2004 ML500, 2005 F150
Get it scanned. It's probably a misfire--you probably got water in a spark plug hole or something. At any rate, we don't know what the code is until you get it scanned. I've always ever washed my engine bay with the engine running and only with a garden hose and simple green or purple power on things like vacuum lines, electrical wires, the like. I'll use a pressure washer if I'm underneath cleaning the transmission, oil pan, or suspension or whatever, that has no wiring or hoses, but yeah, its probably just a little water that got in somewhere it shouldn't be.
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Old 05-20-2019, 05:53 PM
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2014 E350 also restored: 1969 Camaro convertible SS 1957 Chevy Belair 2dr hardtop
I agree let engine run while cleaning. Hopefully it is something minor where water got in
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Old 05-20-2019, 05:59 PM
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1999 ml 430
Thank you very much will do in future, hope the scan comes back clean.
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Old 05-21-2019, 02:59 AM
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I really wouldn't use water to wash new engine compartments using a hose or pressure washer, spray bottle yes but careful. But if you do use high volume water let it sit for 2 or more days in hopefully warm weather to let it dry out before trying to start it. Yeah laugh but it needs to be dry, as you have discovered, and by not being dry something got goofed up. Oh and disconnecting the battery before H2o washing maybe a good idea as well. Even electronic circuit boards can be washed but not electrically activated when wet.
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Old 05-21-2019, 03:28 AM
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In all probability the eng. has multiple misfires and running the eng. will cause serious harm. Water has collected between the spark plugs and the spark plug wires.
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Old 05-21-2019, 03:19 PM
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1999 ml 430
Again thank you for your in put,i dont think ill wash the engine in a newer Mercedes ever.ill keep to the older ones like me
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Old 05-27-2019, 06:30 AM
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ML430, 600SEL
The ignition coils seem to have their plastic coating crack with age, which then makes them susceptible to water and rust, which seems to be able to ruin them at times. When you lose one to this damage the truck will run extremely bad.

If it's just missing a little bit you probably knocked off a vacuum line, got some water in a sensor, or water in the spark plug holes. When it's one of those problems it will usually resolve itself on it's own in my experience.

I had a 93 w124 3 liter I could pressure wash the engine bay till kingdom come, but I had 91 w201 with the 2.6 where if you pressured washed the bay it would kill the car and not allow it to start for hours. Could never figure it out. All my other MB have loved pressure washing but I always stay away from the coil packs.

Try blowing it with air, leaving the hood open in sun, etc. Unplugging, inspecting and unplugging some connectors. And or looking for vacuum lines damaged or unplugged.

The check engine light may remain on until you clear it with a code reader or battery disconnect.
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Old 05-27-2019, 10:55 AM
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1999 ml 430
Thank you, replaced all the plugs, i was going to anyway, found cylinder 7/8 default coil so i have one on order, ill check all connectors, and check vacuum lines,seems that at one point there was a mouse living in the engine bay chewing plastic. so ill give a very good once over.
and yes 124 i believe were the best Mercedes ever built, im always looking for a 300ce my favourite
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