boatman22

When pressure checking for water leaks would you put air pressure to about 20-30 LBS and if it does not hold it means there is a leak, correct? How would you find out where the leak is after you pull the intake and heads off? I have a new rebuild motor and hooked it up to the hose last night and it filled the engine full of water. When I did not see water come out the pipes I shut the water off. Pumped 12 gallons of water out thru the pan until oil showed. Motor was never started or turned over. Pulled water line from stainless marine exhaust and very little water reached them. There must be a massive gap someplace intake, head. Any suggestions?

tssteph

That does not sound good at all. Must be a big leak. I would pull intake off first and check it.

Chris Sunkin

Pull all your water lines off the engine. Block the inlet and exhaust. You can use an expandable rubber plug in the intake and buy a set of NPT threaded flanges for the block intakes. Plug one and attach an air line to the other, then put 20 to 30 psi on it. 90% of new-build water leaks are intake gaskets.

Unfortunately, now you have to question everything in your newly rebuilt engine. I would remove it and return it to the builder and have him go thru every piece of it while I watched. What else got missed?

On gasket leaks- when you see where it was leaking, it's typically very obvious.

boatman22

I unscrewed the oil filter and there was no water......so at least I turned the water off before it got that full. Also no water reached under the valve covers. I removed the temp sender and was going to pressure the system from there.

Photo of the nice new motor, wish water was a good lube

ezstriper

120-130 all day is to cool...you will not burn out condensation at those temps, need 150-160 but also you need to find out what cams you have, wrong overlap will do this no problem, also the old risers/maniflods leaking will do you in. I have seen a lot of guys stick these big cams for auto use in boats only to kill the torque and end up with revision issues..don't keep running to much as it will take out the engines from the diluted oil...Rob

boatman22

Just to update everyone on my problem....I have a cracked block. very disappointing after have it magnafluxed and told it was OK....Now looking for a dart M block if anyone here knows where I can get a deal on one. Sorry to high jack your thread 85baja. I'll start a new one....

nwimbush

It's strange that the same degree of oil contamination is in both engines, which means a design or build issue rather than a failure? I think I also would want to pressure test the water jackets on each engine to ensure no leakage - it's just too painful to have to do a rebuild in the middle of the season.

Yellow_ICC_OK

I would disagree with sunkin on the water/oil issue. I had a formula 272 LS with the same problem. It too did have the older merc manifolds and risers that were not high/long enough to direct the water out the back of the boat. Motors were crate vortec 350's. They would simply eat the water as it came out the manifolds. Replaced risers, problem solved.

Anyone suspect a cracked block here? Has the boat frozen lately? If one cracked, they both could have. However, the fact that BOTH motors are doing the same thing, leads me to believe the risers are inadequate on BOTH motors. Changing to a higher/longer riser should do it. I doubt both gaskets are leaking identically on both motors. Agree with above poster...design issue. Get the exhast, this should solve your problem, and get a few more ponies too.