JVM225
Well-Known Member
My boat is raw water cooled, so I usually pull at least one riser on each motor every year to take a quick look. It's a pretty easy job, and the cost for one set of riser gaskets is pretty minimal.
The wall inside the manifolds/risers that seperate the hot exhaust gas and the raw water will eventually corrode. When this happens, the raw water that leaks in to the exhaust side will be sucked in to the cylinder(s) through the exhaust ports.
If it happens while the motor is running you will notice excessive white smoke coming out the exhaust. This is the water burning off, or making steam, and you will also notice the motor is running hot.
If you catch it at this point you can usually get away with new risers/manifolds, and be on your way.
The big problem is that if the water gets sucked in to the cylinder and sits in there while the boat is at the dock, or laid up for the season. What can happen then is that when you go to start the motor the water and crystalized salt can't compress so it can bend the valves and the connecting rod(s).
This is a good reason to pull your plugs before you re-commission your boat each spring. If you notice evidence of rust or water on a plug then you know you have a problem and you need to correct it before you try to start the motor.
The previous owner of my boat had ceramic coated manifolds and risers installed just before I bought the boat at the start of the 2007 season. I check them annually, and they seem to be holding up extremely well.
They cost more than the regular ones, but I think it might be worth the investment, especially if you have raw water cooled motors.
I've seen the regular non coated off brand ones turn to junk in as little as three seasons. You will save some money on these initially, but they could wind up being more expensive in the long run.
The wall inside the manifolds/risers that seperate the hot exhaust gas and the raw water will eventually corrode. When this happens, the raw water that leaks in to the exhaust side will be sucked in to the cylinder(s) through the exhaust ports.
If it happens while the motor is running you will notice excessive white smoke coming out the exhaust. This is the water burning off, or making steam, and you will also notice the motor is running hot.
If you catch it at this point you can usually get away with new risers/manifolds, and be on your way.
The big problem is that if the water gets sucked in to the cylinder and sits in there while the boat is at the dock, or laid up for the season. What can happen then is that when you go to start the motor the water and crystalized salt can't compress so it can bend the valves and the connecting rod(s).
This is a good reason to pull your plugs before you re-commission your boat each spring. If you notice evidence of rust or water on a plug then you know you have a problem and you need to correct it before you try to start the motor.
The previous owner of my boat had ceramic coated manifolds and risers installed just before I bought the boat at the start of the 2007 season. I check them annually, and they seem to be holding up extremely well.
They cost more than the regular ones, but I think it might be worth the investment, especially if you have raw water cooled motors.
I've seen the regular non coated off brand ones turn to junk in as little as three seasons. You will save some money on these initially, but they could wind up being more expensive in the long run.
