I'm putting new rings in cos I've got a cracked no.3 piston. One of the cylinders has a small ridge at the top of the cylinder where the piston stops..whats the best way of getting rid of it?
Cheers
You can hone it a bit, but try and get rings with a bit cut out just for that, "ridge dodgers" you have to hone the bores anyway to get the glaze off.
When you have done that take a new ring and place it in the bottom of the bore, pushing it down with a piston, check the gap, you are looking for about 25thou, if it's way over that then you are wasting your time with standard rings, because it will be worse at the top, fit oversize and grind the ends down to get a perfect fit.
With the new ring in the bore at several positions, after honing, shine a light up and see if it shines past the rings "oval bores" if it's bad then it's a rebore.
Remember to space the rings out properly, keeping away from the gudgeon pin area. You don't want any of the gaps in this area, and load up the rings and bores with oil when you fit them. The first couple of minutes kills them if they run dry.
You are fitting one new piston so make sure the others have servicable ring groves, and get all the carbon out, either with a broken hacksaw blade or a broken ring. When the rings are on make sure you can rotate them without them snagging, just spin them, a little bit of carbon can make them stick. They obviously dont spin when fitted but thats the way to check they are clean.
Thermal cracking can be caused by a faulty injector, so worth getting them checked.
