Problems with 500hp HELP PLEASE!!!
 

The problem is with a friend of mines boat. They tried posting but are not to computer savy, but are oso members, so I said I would help them and post this. My friends have a formula 353 fast tec with hp500 's Last year both motors had to be rebuilt due to water reversion. They contacted mercruiser and formula and received no help!!! Now both motors have less than 50 hours on them, pulled the plugs and they are soaked with water. They have taken it back to the dealer and he(the dealer) seems to be scratching his head on what to do next? Have read all the articles on the gill exhust, setting the idle speed above 750rpms, and nobody is able to fix this problem. Has anyone else had similar problem like this? Please respond and let us know if you have had any similar experiences like that my help.:rolleyes:

I would start with the manifolds first. pressure check them or fill them with water and if there is a crack you will see water in the exhaust. if it is not reversion and manifolds are not cracked I would say blown head gasket or a cracked block. but I am not an expert. Do all the cylinders have water or just a few?:confused:

Were those exhaust manifolds ever overheated?

All the cylinders have water in them , also it is both motors. Neither was ever overheated.

This sounds like the problem I had. I have sbc the exhaust valve spring broke on #8. Would pull water in and the push it into intake which would flood all cylinders. easy to check with 50 hrs not to likely bought have heard of problems with 500hp and springs early in life.

Check and see if you four inch exhaust risers or the six inch risers. If you have four inch you should be able to get Formular and Mercury to replaced the with the six innch riser exhaust pipes

The motors are both a 98 , with six inch risers. Re-did both set of heads at less than 100 hrs in 2000 , totally rebuilt bout motors in 2001 due to the water.