2007 S550 Low compression one cylinder. Need help
06-30-2015, 04:09 AM
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2007 s550
2007 S550 Low compression one cylinder. Need help
Hey all. Just bought this 07 s550 with only 52k miles, and already have a big problem. I started to notice a rough idle but had no code. Fast forward 2 days later and I finally got a code of p0302 (misfire cylinder 2). I did the basics.
- swapped coils/injector/plug with other cylinder to see if code would travel, but it did not.
- checked compression and I am at 160 all across except for #2 with 85 psi.
I performed a wet compression test, and had no change in compression leading me to believe the problem is with the top end. My question to the forum is if this is a common problem? and if so, what does the issue point to? Burnt valves/carbon build up/seats, etc, etc?
I am planning on removing the intake manifold once I get home over the weekend in hopes of finding a ton of carbon on the intake valves that i can clean off and go about enjoying my new vehicle, but the anticipation is killing me, and thought id post up here to see if anyone had this issue before (btw, I have searched excessively and found only a few very uninformative posts).
In the past, I had a similar issue with a BMW, and used this GM Top end cleaner (i poured it into the cylinder overnight and the next morning sucked it all out, and problem solved). I would like to try that to this car, but would like to know if these motors are timed like others where the intake valves are open at bottom dead center (need them opened so i could soak the backside of the valves.
thanks guys. Really appreciate any help. I am a pretty good wrencher, just don't know a whole lot about mercedes.
- swapped coils/injector/plug with other cylinder to see if code would travel, but it did not.
- checked compression and I am at 160 all across except for #2 with 85 psi.
I performed a wet compression test, and had no change in compression leading me to believe the problem is with the top end. My question to the forum is if this is a common problem? and if so, what does the issue point to? Burnt valves/carbon build up/seats, etc, etc?
I am planning on removing the intake manifold once I get home over the weekend in hopes of finding a ton of carbon on the intake valves that i can clean off and go about enjoying my new vehicle, but the anticipation is killing me, and thought id post up here to see if anyone had this issue before (btw, I have searched excessively and found only a few very uninformative posts).
In the past, I had a similar issue with a BMW, and used this GM Top end cleaner (i poured it into the cylinder overnight and the next morning sucked it all out, and problem solved). I would like to try that to this car, but would like to know if these motors are timed like others where the intake valves are open at bottom dead center (need them opened so i could soak the backside of the valves.
thanks guys. Really appreciate any help. I am a pretty good wrencher, just don't know a whole lot about mercedes.
04-10-2018, 10:24 AM
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2007 S550 /2005 ML350
I have a 2007 s550 with 90000 miles and had the same problem, took it to the dealer and found out that the out-take valves on two of the cylinder are bad. Later found that this is a problem with the 2007 to late 2009 S550.the problem was fixed in late November 2009 after serial number 273.9xx 30 342934. I am in the process of replacing the engine with a 2010 model engine.
