OK, im posting this for someone else, hes a member here and im sure will show up in here eventually. Heres the deal, he had what seemed to be a dead piston in his stock '99 LD9. Showed up out of nowhere while lightly accelerating, next thing you know there was a loss of power and the motor sounds and runs like crap.
Did a leak down test and three cylinders checked out what seemed to be ok and the first cyl #1 was toast. So thats rings or valves depending on where he saw the pressure bleed down thru. I never found out but I did help him tear the motor apart this weekend. Anyway, we tear down the front to get the cam towers free(of cource without checking the timing first like dumbasses). Once we got the cams up the valve #2 on cyl #1 has a nasty hot flat spot on the top of the lobe, look at the lifter and its ground up and broken.....cracked, same with cyl #2 vavle #2 lifter was craked aswell. Ok, so we found the top end problem and in hopes to find a good bottom end we decide to pull the head. On the way down once we pulled the cam housing off the cyl#1 valve #2 spring wasn't up all the way like the other valves(must be bent we thought). Once we pulled the head we found cyl 1 & 2 having exhaust valve lovin. Have not yet had the head dis-assembled or checked the other valves.
Ok, so to get on with the thread, what do you guys think happened? The timing chain tensioner looked good along with all the chain guides. I'm thinking the top end/lifters dry'd up maybe due to the stock old oil pump loosing pressure or something(but never saw the pressure light, but we all know that is BS really anyway) and stuck causing the cam lobe, lifter and valve damage when the piston finally came up and said hello. But when we pulled the towers they traveled the bores just fine..... Maybe a sticky valve guide holding the valve down causing the valve damage but wtf happened to the lifter/cam? Could a lifter being away from the cam(not following) then when the lobe shows up slapping the top cause the hot spot and crack the lifter?......(I just thought about that one right now typing and I'll bet was it).
Let me know what you guys think.
is this an all stock motor??
i always miss the details.
damn.
Pictures? I love valve to piston love.
This is not the engine in question, but here's been my experience with the valve lovin'.
This was caused by a rocker stud being pulled out of the threads in the head, but you have a Camshaft up there with your valves, I do not, so different engine geometry. Gl on finding the problem. You'll probably need a new head if yours is damaged even slightly.
Its really nothing as exciting as that....its just two small indentions on the pistons, #1 and #2 both in exhaust valve #2 location. Head looks great no metal was thrown about anywhere, just a bent valve and indentions on the two pistons. nothing exciting
