klmken

My boat (22Pachanga 454 .060 over Ketih Black 9.5:1 Pistons new rings)started to run funny this weekend ( 20 hours total on new rebuild) cutting in and out at any rpm over 2500. I noticed that my exhaust manifolds were leaking water externally right over the plugs and around the bolt holes. I pulled all the plugs to check for rust and luckily I don't. I did find that the #7 plug had quite a bit of black oil on it but didn't seem fouled. Where could this oil be coming from? Could the motor be cutting out because of water (salt) dripping on the plugs?
Ken

blue thunder

I would concentrate my effort on the water leak at the manifold. Chances are high that if it is leaking extrenally it is leaking internally as well. The plugs may not necessarily look rusty. They may actually look steam cleaned (washed) in appearance. Is it possible #7 is the only plug not getting water... and you are running a little rich? Nonetheless... work the water issue before running any more.

BT

Vinny P

Absolutely check for water problems first. I would pull the risers and look down into the manifolds for signs of water. Next, I would throw away the stock manifolds and get some good after markets.

klmken

High perf manifolds aren't in the budget this year as I have been unemployed for a while. I am looking to get a decent set of stock for a few bucks to get me through October and hopefully the financial situation will be better in the spring.....
What should I look for as far as water intrusion into the motor? I changed the oil immediately after it started missing while I was in the bay and ran 20 mins at idle back to the marina. No water noted in the oil.....

blue thunder

I would pull the riser and look down the combustion gas chamber to see if there are either rust streaks or puddles (of water or rust) at the bottom. Also look on the gasket surface for traces going towards the combustion (exhaust) gas chamber. Heat won't steam clean these areas like in the cylinder and spark plug areas.

BT