overheat, water in cylinders, head gasket or cracked manifold, block?

[acke61]

Ok. 91 mercruiser 4.3 carb w/ thunderbolt IV
Alpha 1 gen 2 outdrive
Repowered in 05 w new engine (jasper) and new exh manifolds


I took it out and overheated it bad. Heard some noises that aren't supposed to come from an engine.

I let off the throttle and as I did it stalled. Engine was real hot and could hear water boiling?

Anyways two days later I try starting it...it runs fine...idled for 15 mins on muffs. Pumped water. I read on here about sucking air from impeller housing so I tore the drive apart and did an impeller kit. Gasket under housing both looks shot so I thought maybe I found the problem.

Went to start it after and it was hydrolocked. Pulled all plugs and all 3 plugs on the side of raw water hose were full of water.

I pulled off riser and manifold to riser gasket looked good. Had water in the jacket. Pulled off exh manifold and the water poured from valve ports.

I plan on doing compression test in like an hour after work.


When I pulled manifold the water inlet on bottom was clogged with rust particles.

Any advice you guys could give would be amazing

 

[Bondo]

Re: overheat, water in cylinders, head gasket or cracked manifold, block?

Ayuh,... Drain the blocks cooling jacket, isoluate it,+ add Air pressure, about 15psi,...
You'll Hear the Leak,.. Follow the Sound...

 

[acke61]

Re: overheat, water in cylinders, head gasket or cracked manifold, block?

Ok so i did a compression test

120 90 then 120 after i added oil
90 70
120 0

There is no water in the oilpan at all...oil looks fine

Cracked block? , Cracked or warped head? Head gasket?

Burnt valve on the cyl thats zero?

I plan on pulling the intake off tomorrow and probably going to pull the head as well...

What should i look for?

Also i plugged up all the exhaust cooling outlets and put water to the block. Water came out the spark plug hole on cyl number 1 (the one with zero compression)

I dont think the piston is bad cuz obviously water isn't blowing by it and getting into the oil pan.

 

[Bondo]

Re: overheat, water in cylinders, head gasket or cracked manifold, block?

What should i look for?

Ayuh,... A New Motor,.... Those #s Ain't to good...

 

[acke61]

Re: overheat, water in cylinders, head gasket or cracked manifold, block?

thats what i'm thinking too...i can get a junkyard 4.3 from a GM and change the core plugs to brass...marine head gaskets...and swap everything over right?