Mark63

I have a 2009 C63AMG

My check engine light has been on and off for the past few months.

I brought it to a mechanic first to have them check out the problem they told it the code read it as a air/vacuum leak.

I then took it to the Mercedes dealership where I bought the car from and they told me it was something wrong with the engines pistons and something about not holding pressure and it would cost me roughly 6000-8000 or more for the repair since I have no warranty.

The car drives great no problems but the engine light worries me.

Sometimes it goes off on its own and sometimes it comes back on and stays on.

Anyone else have this issue?

Also anyone know any good extended or after market warranty?

Ingenieur

Many have issues with the intake gasket causing a vaccum leak
The dealer wants to replace the pistons or rings? Sounds fishy

m a x i m u s

+1. i had the same issue a couple years back.

abcut973

Which code is it exactly throwing?
Go to any auto part store to get it read if you don't have an OBDII reader.
A vacuum leak does not need to have pistons touched to be fixed!lol!

bhamg

The chances of it being piston-related are slim to none assuming the basics, like the car never having been operated with extremely low oil levels etc. If that however might be a possibility after further troubleshooting, have your indie perform leak-down and compression tests. That'll tell you what is going on internally.

estrellajon

Easy to jump to worst case scenario conclusions but get the code first . I doubt it's piston related. More than likely it's intake path related since it's a vacuum leak

avery.whss

if you have a tune..it's that, I had the same problem, had my tune re-adjusted..drove 150km or so and CEL turned off and hasn't come back

JRSJR65

I have had CEL issues the past several months. MB dealership was absolutely no help, blamed it on all the mods I have done and just can't pinpoint cause of CEL...too many codes they said being thrown, mods have caused all kinds of emission issues. Okay? Sent ECM back to Eurocharged for reprogram. That made it go away for awhile. The car has been running very rich for months as well, almost knocks you out from the smell on start up in garage. Finally found a decent performance/maintenance shop locally. They checked codes. found bad O2 sensor on RH side #2. Changed it, the car ran like a champ even tracked it since repaired and no more CEL...but wait that was too good to be true. First time out a week after my track day (yesterday)....well here we go again misfiring bad, worse than ever. CEL of course is back. Took it back to repair shop (Eurosport Automotive) they found 5 of 8 coils malfunctioning. Changed all plugs & coils, hopefully that fixes it for good. Seems to be running 100% again and no CEL. I hope it ends with this last fix! Find a good repair shop before you let any one tear your engine apart. You should be able to get a good referral in your area on these forums.

Merc63

Would help if u told us the code, we can't help guessing in the dark.


There was a m156 locally that came in to the shop with pistons so loose in the bore you could actually wiggle them around with your hand. This was from the factory.

Mark63

I would love to post the code up but the CEL turned off again. Which is a good thing for me, but sooner or later it'll reappear and once it does I will post the error code back up.

Thanks you guys for the help.

Ingenieur

How could the engine run with 0 compression?

How could it leave the factory with 0 compression ?
They spin it with an electric motor to test it
It acts like a compressor/air pump
They measure the current to verify compression/load
???

jvanbrecht

Stored Codes don't necessarily throw a CEL immediately, but running a scan should still bring them up.

I am having this issue with my Secondary Air Injection problem (emissions related, does not effect performance).

I would also like to know some of the codes that JRS was getting. He noted that running rich for a while, really bad for the CATS, and I have a heavy fuel smell on start up as well, and recently a big white puff of smoke from cold start (happened only once on Sat).

sinape62

An understanding of the combustion engine helps not to be duped. Pistons? You would have serious problems, piston rings is another thing. Valves intake/exhaust/ guides are another. How these work together relate to compression.

Merc63

Listen you dummy, a loose piston doesn't mean no compression. The rings provide the seal, not the piston.

Merc63

The codes don't vanish, they are stored, get a odb code puller.

mr747

lol

m a x i m u s

tough crowd.

JRSJR65

I can try and get all recent codes pulled up today. I can't pass emissions testing in Texas until I drive it probably another 100 miles. Guess I need to burn the funkity funk out of the cats...may just go to the local 1/8 mile tonight. That's ALWAYS the best fix on any car...run the **** out of it, clean the pipes out!

Ingenieur

My turds have a higher iq than 3 generations of your family combined

You said it was loose snd could wiggle the piston by hand

To do so the rings must not be contacting the bore

Which means 0 compression
You are full of crap...which is a polite way of saying you are lying or have no clue
Most likely both

I hope you don't work on machines for a living
Your family will be hungry
Lol

Ingenieur

And judging by merc 63's knowledge an ignorant crowd

whoover

Honestly, your hysteria makes it sound like your turds have very little competition in your family.

I understood what he was saying immediately. All pistons have some clearance in the bore, which is dealt with by the rings. Forged pistons have the most clearance because they expand the most. Under the best of circumstances you can move a cold piston laterally with the rings continuing to seal.

I understood the observation was that the clearance was excessive, with the small rocking of a few thousandths replaced by obvious play of maybe 5 or 10 thousandths. The rings fit hundreds of thousandths in their grooves, so they will continue to seal. This is what causes piston slap, which doesn't mean zero compression.

Ingenieur

Your passive anger is omly exceeded by your rant
And my turds would be right at home at your dinner table
I know I have hurt your feelings
Move on
Get over it
Put your big boy pants on

If you think you can wiggle pistons, ie, a lot of slop, and still pass a factory compression test my turds have more mechanical apptitude than you do
It would knock (mechanically not ping or det) and shake
And make no power
May not even sustain combustion

I have no doubt you understood what he wrote
It was nonsense
Much like 1% tire od renders tcs inoperable
Sense a few 1000th's play? By feel? Right-o bucko

whoover

http://www.merriam-webster.com/dictionary/rant

Ingenieur

Is that a picture of you next to the word rant?

JRSJR65

CAL warning. Check-Attitude-Light going off pretty bad here.