Mcm 120/140 blown head gasket and or cracked block?

[Unluckyboating]

Well we didn’t winterized the boat this year, and it sat last year uncovered for the whole summer. I know I’m a terrible for doing so. I have learned my lesson to winterize and store!

I put the muffs on to see what damage I caused. I noticed a freeze plug plug in the back of the engine was leaking water. I had to pull the engine and replace the freeze plug and reinstalled the engine.(lots of work)

I thought I was lake ready. But just to be sure I was readjusting timing due to some rough running. Todo so I had to remove the fuel pump to loosen the distributor bolt.

Thats when i noticed my oil! It was milky brown. Classic water in oil look.

After doing some reaearch i desided to only do a compression test for the cylinders. 1st 120 2nd 60 3rd 60 4th 120

i take the heads off and inspected the gasket well it blew out between 2&3 for sure. I can’t see any other defects with the head gasket.

I cannot see with my eyes any cracks on the block, head or manifold. I fear a crack is in an area I can’t see and I’m going replace the gasket, button everything up and still have water in my oil and have to replace the bottom of the engine.

Two questions.

1.When a gasket fails between two cylinders, could it cause water in the oil?

2. Are there any other things I should consider.

Thanks everyone!

 

[Scott Danforth]

1. Yes
2. Pressure test your block after you get it back together

 

[Oshkosh1]

1. No...IF it fails only at the "saddles" between two adjacent cylinders it will NOT leak AF but you will have very low compression in both. In order to introduce AF, the gasket must fail between a coolant passage and a cylinder or an oil passage.

2. The head and block can fail internally.

3. The heads need to be magnetic particle/pressure tested at a shop...that's the ONLY way to verify they're not compromised.

 

[Unluckyboating]

[No message]

 

[Oshkosh1]

Although I have repaired a number of blocks and heads using Lock-N-Stitch with great success...it's easier to get a new lump. I've pinned a couple of windowed rare tractor blocks but in your case it's better that you just start over...

 

[Scott06]

As above just get a new block longblock or complete engine from a junked boat. No sense repairing a block that isn't rare.