Teardown!

[ffgb]

Well, I just took off the head on my motor to see the bottom side of it and to see the top of the pistons.  I don't have pics right now because it was dark, but will have some tomorrow when it is nice and bright.  A quick summary:  The top of the pistons all have a valve impression.  Also, about 1/2" down on every cylinder, there is a slight ring/groove/ridge 360 degrees.  Have any of you guys reuse pistons that have a valve impression on them?  Other than the ridge, there is no scoring or scratches on the cylinder walls, definitely shiny and glazed.  For the bottom of the cylinder head, there are absolutely no cracks whatsoever in between the intake and exhaust valves, pretty sweet!  I have to take out the pistons, but worried about the little ridge, I don't know if the piston will come out from the top, I guess I just have to try.  I have to get my engine block to a machine shop to have them check the bores and pistons, we'll see.

[Vincent Waldon]

I've got an engine happily using pistons that looked like this:




If you can feel the ridge with a fingertip it's very risky to try to remove the piston without dealing with the ridge...you risk breaking rings or worse a ring land on the piston.    

There's a de-ridging tool you can buy....or just get the machine shop to do it for you.  

The sad news is that if you can feel the ridge it also likely means the bores are worn beyond spec...diesel clearances are very very tight... but again your machine shop will help you figure it out.