Piston head damage

[fluke12]

Started pulling apart my cl350 to find out why I have low compression in one cylinder and have the top half apart. All my gaskets seemed to be fine (until I destroyed them all taking everything apart) and rings all seem in tact.

But the piston head has a small tooling mark from where the spark plug hole had to be sleeved and was done incorrectly. Is that a big enough notch to worry about?

 

[xb33bsa]

no,that Is not a problem
what you should do is check the cylinder to piston clearance,cylinder roundness, taper etc see if they are still viable
or have a qualified someone do that for you
also you need to check out the head,cam,valves and seats and guides,camshaft endplay etc all of the specs are in the factory service manual

 

[fluke12]

Yeah I plan to measure everything like the manual says. I've never opened up an engine before and I saw that cut and got concerned.

As far as the low compression, I plan to see if I can't find the problem before I take it anywhere.