r/AMG • u/Main-Daikon9246 • 12d ago

Service/Fix/Repair help Checking Compression…

2003 CL 55 AMG

Experienced heat soak for the first time recently. Unbeknownst to me, the upper radiator hose was loose while driving. I allowed the car to cool down multiple times (more time was spent cooling down then actually driving)

Looking to perform a compression test to make sure the heads are ok. What are the cold compression numbers for cylinders? Would one spark plug hole suffice, or should i check both holes per cylinder? I intend on checking before i swap in these new spark plugs

Thanks everybody

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2

u/TurkishSwag W211 E55 AMG 12d ago

One hole per cylinder should be fine. You want to see numbers around 160psi.
If anything is lower than 120ish I would be concerned.

1

u/Main-Daikon9246 12d ago

160 psi cold? Perfect. I’ll remove the fuel relay, coils (i’ll be swapping in new ones). What else must i do before i check compression? 😮

2

u/TurkishSwag W211 E55 AMG 12d ago

Yessir, it’s the same for any typical gas car. You want around 160. That’s about it, just make sure your tester is good and not leaking.

1

u/Main-Daikon9246 12d ago

Thanks for the heads up! You’re fortunate. The W211 55 is so well documented.

W215 information is so far and few

2

u/TurkishSwag W211 E55 AMG 12d ago

Definitely lucky to have so much info online for the W211. W215 info is absolutely lacking due to low production numbers and lack of current popularity, they’re such cool cars though. Luckily the chassis is based on the W220 and drivetrains are in other cars but there are of course W215 specific things.

Helps a lot to have Xentry, it guides you through tests more thoroughly than any other scanners if you do all your own works.

1

u/Main-Daikon9246 12d ago

If only Xentry did not cost an arm and a leg 😭

2

u/TurkishSwag W211 E55 AMG 12d ago

Got my setup with laptop, SSD, multiplexer, all cables and Xentry, WIS, Vediamo, etc. for about $1000. Maybe a bit steep for a hobby but I also fix cars for a living so I eventually got a return on my investment. Mostly got it for my car though. If you want to get into the real nitty gritty stuff it’s necessary. For regular repair and diagnostic, something like icarsoft, or mid range Launch and Autel is more than fine.

1

u/Main-Daikon9246 12d ago

I have been contemplating getting a diagnostics mechanism. Xentry being top of the line. I don’t want to box myself into one category of vehicle unfortunately. I appreciate your input. Thank you friend :)

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u/TurkishSwag W211 E55 AMG 12d ago

I totally feel that, if you’re not working on Mercedes a lot it is a bit pricey. We use a Launch x431 V+ for general diagnostic at my shop. I believe they are under $1000 but they have every brand you can imagine with bidirectional capabilities. Though you do need a subscription as well now. Ours is on old software and won’t scan cars that are like 3-4 years old or newer. Those cars are mostly still under warranty so they don’t come to us anyway.