Hey guys, my mate bought a ‘00 610e recently as a non runner. Initial troubleshooting revealed no spark. Dead CDI was the culprit. Long story short it also has very poor compression shown during a leak down test. One inlet valve and both exhaust valves leaking along with a stuck piston ring. Cylinder has vertical marks on it but I can’t catch a nail on them. Slight edge on the lowest position where the rings stop on the cylinder. There’s marks on the piston where the exhaust valves have touched in the past but the build up of carbon suggests it isn’t recent. What are my options to remedy the situation? I’m guessing the cylinder is plated, so best scenario would be honing if marks aren’t too deep. What are the success rates of freeing a stuck ring? I couldn’t see any damage along the groove that was causing it to stick. Providing my valves aren’t bent, would I get away with lapping the valves to the seats? I will try and post some photos of the damage tomorrow whenever I get a chance.
You can probably free the ring by soaking the piston in gasoline, brake cleaner or carb cleaner, but by looking at it I would really consider doing a good rebuild, plating the cylinder and using a fresh piston. The valves need to be inspected, if they touched the piston at some point they may also be bent and should be replaced, if for some reason they are straight you may get away by grinding the surfaces (if they are no Titanium valves) Cheers.
Bit of an update. Decided to replate and get a new piston and second hand head. That didn’t pan out as the cylinder turned out to be cracked. Got my hands on a good used piston, cylinder and head. Happy days! Been cleaning up the parts ready for assembly but I’m struggling to figure out which is the front of the piston as it’s different to the original piston. As you can see above the original has depressions for the valves but this one is dished and has no arrow to distinguish front from back Anyone know which direction is front?
