03sl55amgmjd

Dear forum members,
my biggest nightmare came true and i sure could use some direction from knowlegeable members.
My mechanic performed a compression test on cylinder 8 and the results were poor. Cylinder not holding pressure. He also said he saw a lot of blow-by.
He referred me to a local engine rebuild center specializing in BMW, Mercedes, etc.
Before the compression test was done, I changed the ignition coil and plugs which did nothing. Upon the test ride after the replacement of those parts, the car had no power, misfired and idled very rough. I removed the plugs after my short test ride and they were black and oily in only a few mile drive. I realize this is limited info but I wanted to get some input on whether or not an engine replacement could be an option seeing that a valve job, piston and ring change, cylinder maching job will probably cost more than just replacing the whole motor then parting out my removed motor to make some of my money back.
If anyone can steer me in the right direction, I would greatly appreciate it.
The car is an 03 SL55 AMG with 80k miles on it.
Thanks in advance.

Forum members,
I'm adding new information to my last post as something crazy has happened.
Since it's a nice day in NJ today, I figured I'd at least wash the car which I did.
I started it up and there was no more rough idle, no smoke exited the exhaust upon start up and the check engine light has cleared itself. I took it for a drive and it runs fine. With this info now, can anyone advise me what that means? Is there a component in the engine that can intermittently function properly sometimes and then fail at a different time? Obviously it cant be a cracked cylinder head or block. Piston and rings cant sometimes operate properly so can someone school me on what could be the component that can be hanging up or sticking open/closed causing my original symptoms noted in the initial post. I guess this is good news as I was thinking i may need a different engine.
Hope to hear from some members soon.
Thanks much!!!

BlownV8

Just drop in a good used engine. Will be much cheaper and probably more dependable than a rebuild.

Vader1

You can probably find a good sL55 amg engine with lower mileage for less

poppyboy

Curious about the root cause, as these engines (if well maintained) are generally bulletproof.

E55Greasemonkey

Verify any damage to cylinder 8 with a borescope before making a decision.

E55Greasemonkey

It sounds like you had a misfire and the cylinder may have washed down right before the compression check. That, or you had a valve partially stuck open which later cleared itself. How old are your plug wires? Another possibility is a bad or clogged injector. Drive it some more, if it happens again swap plug wires to another cylinder (that use those same length wires) and if the problem persists, you can swap the injector to another cylinder as well. What you are trying to do is see if the problem moves.

Tommyboy928

I agree with you, plug wires ,people not talk about , we changed on 2 x 55 engines with close to 100 k miles the plug wires to 10 mm race wires , and result was stunning huge difference in power , on my car 2007 with only 38 000 miles we also changed to 10 mm race wires ,and you can feel the difference . My cables was perfect condition stock . BUT guys with alot miles on this engines, should all change their Spark wires .

Tommyboy928

I agree with you, plug wires ,people not talk about , we changed on 2 x 55 engines with close to 100 k miles the plug wires to 10 mm race wires , and result was stunning huge difference in power , on my car 2007 with only 38 000 miles we also changed to 10 mm race wires ,and you can feel the difference . My cables was perfect condition stock . BUT guys with alot miles on this engines, should all change their Spark wires .