PatriYacht

I would agree with all of these guys, the problem is in the cyl. heads, exaust manifolds. Guides are causing valves to stick. Could be because water is getting to the head causing corrosion. These are old engines, exposed to salt water for a long time. Taking apart the bottom ends will just cost a lot of money.

cig1988

Patriyacht has a good point! I would never imagine in a million years the design of a stock riser would cause a problem. Took me a few weeks to figure it out after changing intake,exhaust gaskets... pressure testing this/that. Came close to winterizing the boat in July!

PatriYacht

My father in law boats around Long Island. His boat sits in the water all summer. After 3 years, he had to replace the exhaust manifolds. They were already leaking. It makes you wonder how long the rest of the engine will last.

PatriYacht

Offthefront, did you check the valveguide to valvestem clearence. I've heard of valveguides cracking also.

offthefront

iTrader: (1)

head shop inspected the heads ...replaced 2 valves and all exhaust seats ...they will have to go back this week ..I am sure we find something else ...

Lmarth

I've been watching the two threads on this situation and have to admit that it's a bit of a muddle. The worst situation is that after 25 hrs, the valves are hitting the pistons of what should be a very mildly built motor. Sorry, but I don't think the problem is in the bottom end. Nor do I think a stuck valve or reversion caused the valves to hit the pistons. The way us old timers used to check valve to piston clearance with high compression (domed pistons) was to put the pistons at TDC with the valves fully open and check the clearance. This way, you could float the valves or have a timing chain let go and not grenade the motor. Obviously, the valves shouldn't be full open with the pistons at TDC unless something unnatural happened. I'm puzzled as to how a relatively low compression motor cold have valves in several cylinders stick full open and hit the pistons. Having said that, the many folks here that know more than me can enlighten me. Moving on, this is supposedly a Jasper long block. Is it a maranized long block? What's the cam and it's Lobe Separation (LSA)? Sounds like reversion or water getting into the cylinders (risers) could be another problem. I believe Offthefront said it ran fine on the hose until he took the boat out on the water. Were the exhaust manifolds pressure checked? Without seeing the motor as it was disassembled it's hard to comment further, but the valves hitting the pistons in several cylinders really puzzles me. Keep us posted. Lou

offthefront

iTrader: (1)

ok .. first time only one valve hit piston ...the other was stuck open but did not contact the piston ...this time its the same piston ..same valve ....the other side seems ok ...I went by the shop today and they showed me the lifter and you can see where the pushrod has walked around in the lifter ....so either the lifter is not pumping up or spring tension bad or bad adjustment ? I dont know ....If I knew .. I would be doing the repair and not them ...

PatriYacht

If the valve is sticking, the push rod would bounce around because there is no spring pressure on it. That is not your problem.

Lmarth

Mike-- Patri Yacht is correct. If the valve is stuck in the guide partially open, there will be play in the pushrod until the cam tries to open the valve further. Then something's got to give which would show as a chewed up seat in the lifter. What you're describing is the result of your problem and not the cause as he suggests. If water is getting in the cylinders, it would explain warped/stuck valves. It does not explain the valves hitting the piston. I know this is frustrating not to mention expensive. We've all been there and are just trying to help.

cig1988

Offthefront, as I said in one of my post. I have the 365 mag's and the aftermarket risers made no differance w/the old cam. As soon as I changed to a new cam (same spec) I had problems with water. It was plain to see with the bore scope I was having a problem with water in the exhaust. And yes, the stem of the valves were pretty rusty by just running the garden hose thru the engine. This was driving me up a f'in wall. The design of the riser was at fault.