Two things I know of will cause it.
1. Old age and it was just time.
2. You have a water supply problem to the manifold (usually the problem) and it melted the aluminum.
I just bought a 20 miller with stock BBC 454 took it out to the lake today. Boat ran good until a hole aperd in one of my logs. I was wot for a bought 60 seconds win I herd the leek. Is this common for logs or is there some thing that would cause this to happen. Learning a lot and still more to learn
Two things I know of will cause it.
1. Old age and it was just time.
2. You have a water supply problem to the manifold (usually the problem) and it melted the aluminum.
saw that once before, only thing we could come up with on his was a lean condition?
Last summer the aluminum water cooled OT's I was running melted a bit between the log and the water inlet. I thought aluminum's melting point was like 1500º?
make sure they're plumbed the right way. In at the bottom, out at the top.
Had the same thing happen on an Olds with logs.
It was a lean condition at WOT.
REjetted 1 size up on secondaries,seemed to fix it.
Was running rich at idle but when you put the coal to it it was leaning out causing the logs to heat up at the flange.I melted 2 holes before i noticed it,with enclosed engine.
I hydraulic my engine with a set of leaking jacketed headers once. Might want to pull your spark plugs and look for H20. :frown:
Ran fine until shut down, water in the pipes back flows into engine, then starter grinds on the next start or hard starts, etc. Hope thats not the case with you. Not sure if that's even a factor with logs.
I was sort of thinking that it could have been caused by a lean condition. Checked the hoses and their run propley. The carb is on the worn out side so I think it will be replaced soon with bigger jets in secondarys.
Being a stock motor that was assumably running I hadn't considered lean being a problem. But it can definately cause that too if WOT for extended period. It can also hurt engine parts.
I ran mine 1 time for about 5 minutes WOT with NO water running through 1 log and had no melting to the log, I did however melt the rubber sleeve and almost sunk the boat. The whole reason I was at WOT was because I blew off a coolant line and was filling up with water. Little did I know if I had just shut it down it would have turned out better.
Does it REALLY matter which is the "inlet" and which is the "outlet" on a set of log-manifolds???
I didn't even consider the possibility of a "correct" inlet and outlet when I plumbed mine...