Disassembling Merc 4 cyl. W/stuck piston

[beerman57]

The crank is out, #4 piston is still in the cyl. I wonder if this motor was bad from the factory, looks like it might have 100 hours or so on it going by the 3 good pistons, needle bearings from conn. rod to crank look like new, rings look like new. #4 needle bearings are not round any more, not even close. What could cause #4 to have such a problem, but #1,2 and 3 look like it’s barely broke in?

[dave-bernard]

water in the bottom, bad lower crank seals

[beerman57]

But why on such a fresh / new looking motor? The bottom main bearing was toast too.

[Anonymous]

In the past, I have used a brass rod and a hammer to tap to piston out. The piston most likely junk anyways, so if you do damage the piston, no big loss. A piece of delrin(hard plastic) would work as well.

[Author]

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