Help with water in oil

[Nbaas]

4.3 mercruiser, Purchased the boat 2 months ago. 3 trips on the water. ran great then ran bad then ran great and then really bad. plugs are black. leakdown test showed one bad intake valve (50 vs. 180) in rear port cylinder. pulled the heads for a valve job. both rear cylinders had about 2 tbsp of water in them. similar issue? can both head gaskets fail at the same time? no. 1992 alpha 1 carb V6.

 

[Lou C]

Yes both HGs can fail at the same time if the engine had a bad overheat in the past, which then would let water in the cyls depending on where the gasket blew. The water in cyls would then cause the sticking valves. The water in cyls can also be caused by a leaky rusted exhaust manifold and/or elbow.
Mine had a bad overheat and then ran fine 2 more seasons, toward the end of the 3rd the HGs blew and my initial symptom was hard starting due to sticky valves. I wound up replacing the cyl heads.

 

[Searay205]

my guess your manifolds are leaking, either at manifold to riser connection or manifold rotted through on back side of exhaust valve.

 

[Lou C]

Or even the cyl heads could have rotted through. In any case if the water in the oil is addressed right away the short block may be salvagable. That's what I did with mine.

 

[Nbaas]

Yes both HGs can fail at the same time if the engine had a bad overheat in the past, which then would let water in the cyls depending on where the gasket blew. The water in cyls would then cause the sticking valves. The water in cyls can also be caused by a leaky rusted exhaust manifold and/or elbow.
Mine had a bad overheat and then ran fine 2 more seasons, toward the end of the 3rd the HGs blew and my initial symptom was hard starting due to sticky valves. I wound up replacing the cyl heads.

The engine ran like a top, when it did, for the first 20 minutes or so. last time out had a great Friday, great Saturday morning, started losing power and bogging down a bit in the afternoon and then backfired twice under load. fuel odour in the exhaust. put the boat on the trailer. said a bunch of bad words. ran a leakdown test. 1 bad intake valve. mercarb mixture screw was about 5 turns out. not sure if that is related. I mentioned this on another thread, but this boat exploded a spark plug a month ago (blew the ceramic and the post straight out of the engine). no damage to the cylinder or piston. anyway heads are headed to the valve shop. I think I have a valve/carb/ignition combo problem maybe? anyone want a 1992 Bayliner?

 

[Nbaas]

Or even the cyl heads could have rotted through. In any case if the water in the oil is addressed right away the short block may be salvagable. That's what I did with mine.

Thanks Lou. No water in the oil. thankfully.

 

[tpenfield]

Seems like the the OP's thread has been Hijacked

Anyway the Mods may be along to clean things up.

@h22221 to your question about #6 being able to put water in 2 &
#4 . . . Yes, it can/will do that at idle speeds as there will be a slight amount of exhaust reversion. #6 will put water in the exhaust manifold and #2, #4 will take some of it in at the top of the exhaust stroke.

The engine looks like it has seen some salt water, probably the cause of the rust-thru in the cylinder head. I assume the metal flakes tasted salty

BTDT - with my 1991 7.4L Merc . . . an amazing amount of metal flake came out of the engine block when I re-built it. Of course it did not last long after that.

Would it be better to get a 4.3 long block at this point?

 

[h22221]

Seems like the the OP's thread has been Hijacked

Anyway the Mods may be along to clean things up.

@h22221 to your question about #6 being able to put water in 2 &
#4 . . . Yes, it can/will do that at idle speeds as there will be a slight amount of exhaust reversion. #6 will put water in the exhaust manifold and #2, #4 will take some of it in at the top of the exhaust stroke.

The engine looks like it has seen some salt water, probably the cause of the rust-thru in the cylinder head. I assume the metal flakes tasted salty

BTDT - with my 1991 7.4L Merc . . . an amazing amount of metal flake came out of the engine block when I re-built it. Of course it did not last long after that.

Would it be better to get a 4.3 long block at this point?

Thanks, I've fitted new heads today, just waiting for some final bits to arrive and I will be testing next Friday....

I aquasteeled the block, so hopefully it will slow down any more corrosion, and I will flush after every use with oily water, and will be filling with anti freeze over winter so fingers crossed the block won't get any worse.... Just hope it's not cracked anywhere, but never overheated and didn't leak/have symptoms of a cracked block before all these issues, so here's to hoping!