Quote:
Originally posted by Kodiak
Ok, here we go again. I got the top end of this engine tore down today and here is what I found. #1 Piston was cracked, #2 piston was fine, #3 piston was busted, #4 piston was busted, #5 piston was busted, #6 piston was busted, #7 piston was cracked, #8 piston was busted. All pistons was busted just as the ones in the pics. One thing I did notice was all pistons was busted or cracked right at the exhaust valves. The pic of the two, I checked and they also was busted at the exhaust valves. I checked the deck height and the pistons clear and do not stick out above the block. I also checked the exhaust valves and the were not hitting the pistons. I don't really think I have a lean mixture problem whereas the top of the pistons were covered with black soot along with the heads. I'm wondering if the timing could be causing a "hot spot" on the pistons and making them weak at that point.
Kodiak
kodiak i don't see how you're gonna have soot at one place and a hot spot at another on the same piston if its heat doing the damage. if youve got that much heat , you should be able to see it. The top of the piston ant that big. is the cracked pistons cracked towards the front of the motor or to the rear of the motor? Something is jerking the top of those pistons off. why the exhaust valve? i don't see anything hitting the top of the piston. looks like the top of the pistons are being pulled up and for that to happen the piston would have to be rocking back and forth or cocking some how. also on the heat thing if it was heat it should show some damage down the side of the piston where the piston broke. It would try to go down passed the ring before it would burn a hole in the piston, don't see any damage on the sides. how about if the block was bored at the wrong angle, couldn't that put a drag on one side of the piston? Its been done before. are you sure that the ring is not loose in the in the ring grove? some things to look at and think about. :confused: