Im going to the shop tomorrow morning to check what he says, just doesnt sount right to me, the engine turns very good, plus it didnt freeze on me , i shut if down myself, the motor its a 502 marine engine, the guy who i bought the boat from bought it new in july 2003, I will post tomorrow exactly what the guy did to determine the status of the engine. thanks for all the replies, ill be back tomorrow with more news. thanks to all

I would pressure test the manifold and also be sure to do a leak down compression test on all the cylinders.

conducting a leak down test will help verify if there is a problem with the head gasket before you pull the motor apart.

If you are getting water in all 4 cylinders on one side of the motor I would first guess that there is a leak in the exhaust manifold , or the manifold to riser gasket is bad

well, it was a head gasket, actually both heads, i thought it was the exaust since there was water in all cilinders but that wasnt the case, when the boat overheated it went to like aroun 230, to me that didnt seem that hot to bust both heads, i've had my suv at 260 once and its ok, is there a difference in a marine engine? I appreciate all the guys that help me solve this problem. Thanks again guys.

Ordering the temp and oil buzzer today , maybe the light also, cant never be too safe.

of COURSE there is a difference...

Your SUV isn't running at 450+ horsepower continuously as it runs down the interstate at 65mph overheating at 260 degrees. Probably doesn't take but 40 horsepower to maintain highway speed in your SUV. Loads are minimal and combustion pressures are minimal. Additional temperature in the SUV is just that - some additional temperature. With proper levels of antifreeze (50%) your SUV's coolant won't even boil at 15psi (which is what the pressure cap is) until around 265-270. Cooling is still distributed evenly, even though the cap will be hissing.

Your boat has NO antifreeze. At Zero psi of water pressure, the coolant boils at 212 degrees. At 15psi, it boils around 230. Boiling coolant creates air pockets, and guess where they are - at the TOP of the engine - in and around the cylinder heads. Right where the heat needs to be removed most dramatically.

At 450hp, your motor is operating at very high cylinder pressures. The cooling system will be working very hard. Any shortcoming will cause engine temps to begin to rise. Additional temperatures equal additional cylinder pressures. An gasoline engine can only stand so much cylinder pressure until the fuel burn becomes uncontrolled, resulting in DETONATION. Detonation is an explosion of the fuel, not a controlled burn. Detonation causes cylinder pressures to spike to obscene levels. If allowed to run very long in this manner, something's gotta go.

Sounds like you ran it and ran it and then when it refused to run, you tried to run it some more.

You should be extremely happy that the headgaskets let loose. It saved your hard parts.

Thumbs up on the alarm. Lights are okay, but you end up never seeing them on a sunny day. Place the buzzer very close to your ears - experiment with different positions under the dash and find a place where wind noise won't cover it up. Some setups have an external relay connection. i would advise rigging it up to your stereo amp's trigger lead so that if the buzzer goes off, it kills the stereo, so you don't have to worry about Van Halen covering up the sound. (the trigger wire on the amp will usually be blue or be labeled "trigger, on, power antenna" or something like that. You don't want to relay the power to the amp cause you will need a huge relay and it is not healthy to some amps to have the main power cut off during high output usage (some have fans that should run a cool down cycle, etc).

[QUOTE]Originally posted by migara422
well, it was a head gasket, actually both heads, i thought it was the exaust since there was water in all cilinders but that wasnt the case, when the boat overheated it went to like aroun 230, to me that didnt seem that hot to bust both heads, i've had my suv at 260 once and its ok, is there a difference in a marine engine? I appreciate all the guys that help me solve this problem. Thanks again guys.

Ordering the temp and oil buzzer today , maybe the light also, cant never be too safe. [/QUOTE

I would make sure they check the heads for cracks and that nothing is warped. While the heads are off take a look at cylinder walls for any scoring. Not to point at the worst but if you get it right now you will have a great summer ahead with no trouble. If you got it hot enough to burn both head gaskets it got really hot. Water temp gauges with little or no water give incorrect readings. Alarms a great idea. Hope all goes well. :)

I don't think he "burned" the gaskets. I think he "blew" them.

Yes, scoring and/or accelerated bore wear (a ridge at the top of the stroke) could result from use at oil temps above 300 degrees. I am hopeful that his oil didn't get that hot.

Depends on how long it ran dry. At high cruise, it usually doesn't take very long...

I didnt run the engine after i shut it down, when i notice it got hot i shut it off, then when i saw water coming through the headers i figured i start it up to get water through the block but coulnt start, actually the reason why it woulnt start is that i found the wire that goes from the distributor to the coil was broken, so i think that was a blessing on its own.

can a marine engine hydo lock and crack 2 cyl walls and not bend the connecting rods. Is this possible

hydo locked engine
 

Can a engine hydro lock and crack two cyl walls and not bend or dammage the connecting rods. Is this possible

Fixx
 

Depends on what connecting rods you have, iv see it do both,bend the rod and or blow a hole in the cylinder.