Hey all, i am in need of some advice...
i bought a 98 formula 34pc with mercruiser 7.4 LX and B3's in the fall, had it winterized before it was transported to my marina, and it sat there all winter. I put the boat in the water yesterday for the first time and had some issues. The boat fired up and ran great, at first. Shortly after leaving the dock, the starboard engine started to heat up. I shut it down at 190 degrees, and idled on the other engine over to my slip at the marina. I went out and bought another water pump impeller and replaced it the same day (the old one was toast)...no big deal. it was about 2 hours from the time it ran to the slip, and the time i got the water pump replaced and tried to restart.
now the odd part...when i went to start the motor again, it turned 1/4 turn and locked up. i pulled all 8 sparkplugs and it turned over fine, but it shot water out of most of the cylinders. it came from both sides of the motor. it was a significant amount of water, and obviously enough to hydrolock the motor. all 8 cylinders are moving, as i tested by putting my finger over the spark plug hole, that doesn't verify that it doesn't have a bent rod, but at least it didn't break one. this is a problem to investigate later, but i need to find where the water came from. sidenote, is the starter motor on a 7.4 strong enough to bend a rod?
I'm thinking that it has to come from either intake manifold or exhaust manifold. There is no water in the oil, so the only way water can get to the cylinders without getting in the oil is either the intake or exhaust manifolds. i took the port manifold and riser off and inspected. i can't seem to find anything obvious where it may be cracked. i filled the manifold full of water and let it sit on the dock for a few hours and it did not leak down. next, i wanted to test the riser, but i don't know how i can seal the riser to be able to see if it leaks at all. any ideas how to seal the angled end where the boot goes to the y-pipe? Also, what is the small hole (maybe 1/4") at the top of the riser (on the inside)? it is almost in the center of the riser exhaust port.
so my preliminary theory goes like this...There was pink antifreeze still in the outlet line from the old raw water pump when i pulled it to replace the impeller. obviously it hadn't moved much water through the engine. i'm thinking the water pump was inadequate in the fall for when the marina winterized the engine, and didn't pump antifreeze all the way through the motor as it should. also another interesting observation is that when i pulled the thermostat housing, there was water below the thermostat. The motor had been run for a few minutes, but since there was still antifreeze in the outlet from the raw water pump, it hadn't moved any through the motor while running. if there was water below the thermostat, that means it was in there all winter...right? Also the fact that there was even a thermostat in the motor after being winterized is a mystery to me too. i always pulled my thermostats when i winterize to make sure antifreeze goes all the way through the motors.
anybody have any other ideas where the water could come from or any other things i can do to test? maybe some of you can verify or refute my theories as well? the boat was surveyed and sea trialed in the fall before buying it, and everything was fine with both engines. the only thing that happened after survey and sea trial was they were winterized by the marina where i bought it.
i bought a 98 formula 34pc with mercruiser 7.4 LX and B3's in the fall, had it winterized before it was transported to my marina, and it sat there all winter. I put the boat in the water yesterday for the first time and had some issues. The boat fired up and ran great, at first. Shortly after leaving the dock, the starboard engine started to heat up. I shut it down at 190 degrees, and idled on the other engine over to my slip at the marina. I went out and bought another water pump impeller and replaced it the same day (the old one was toast)...no big deal. it was about 2 hours from the time it ran to the slip, and the time i got the water pump replaced and tried to restart.
now the odd part...when i went to start the motor again, it turned 1/4 turn and locked up. i pulled all 8 sparkplugs and it turned over fine, but it shot water out of most of the cylinders. it came from both sides of the motor. it was a significant amount of water, and obviously enough to hydrolock the motor. all 8 cylinders are moving, as i tested by putting my finger over the spark plug hole, that doesn't verify that it doesn't have a bent rod, but at least it didn't break one. this is a problem to investigate later, but i need to find where the water came from. sidenote, is the starter motor on a 7.4 strong enough to bend a rod?
I'm thinking that it has to come from either intake manifold or exhaust manifold. There is no water in the oil, so the only way water can get to the cylinders without getting in the oil is either the intake or exhaust manifolds. i took the port manifold and riser off and inspected. i can't seem to find anything obvious where it may be cracked. i filled the manifold full of water and let it sit on the dock for a few hours and it did not leak down. next, i wanted to test the riser, but i don't know how i can seal the riser to be able to see if it leaks at all. any ideas how to seal the angled end where the boot goes to the y-pipe? Also, what is the small hole (maybe 1/4") at the top of the riser (on the inside)? it is almost in the center of the riser exhaust port.
so my preliminary theory goes like this...There was pink antifreeze still in the outlet line from the old raw water pump when i pulled it to replace the impeller. obviously it hadn't moved much water through the engine. i'm thinking the water pump was inadequate in the fall for when the marina winterized the engine, and didn't pump antifreeze all the way through the motor as it should. also another interesting observation is that when i pulled the thermostat housing, there was water below the thermostat. The motor had been run for a few minutes, but since there was still antifreeze in the outlet from the raw water pump, it hadn't moved any through the motor while running. if there was water below the thermostat, that means it was in there all winter...right? Also the fact that there was even a thermostat in the motor after being winterized is a mystery to me too. i always pulled my thermostats when i winterize to make sure antifreeze goes all the way through the motors.
anybody have any other ideas where the water could come from or any other things i can do to test? maybe some of you can verify or refute my theories as well? the boat was surveyed and sea trialed in the fall before buying it, and everything was fine with both engines. the only thing that happened after survey and sea trial was they were winterized by the marina where i bought it.
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