1986 Mercruiser 260 hp V8 water in cylinders

[dan2744]

So I finally got this thing to start and idle, I put it on muffs and it quit after idling it for about a minute. I shut it off and then it wouldnt start back up and it turned over slow. I pulled plugs and the #8 cylinder was full of water and 2,4 and 6 had some. I had no water in the 1,3,5,7. I pulled off riser and didnt see anything that jumped out at me. I pulled the manifold and didnt see anything there either. Im leaning towards head gasket or cracked block. What do I look for in a bad riser gasket? I have good compression, whatever it is is a really bad leak and fills up crankcase and cylinder pretty fast. On the bright side, impeller works!

 

[Scott Danforth]

you look at the gasket mating surface for a riser issue
you pressure test the block and heads for a crack or a head gasket issue.

did you winterize yourself? if so, how did you do it?

 

[Bondo]

What do I look for in a bad riser gasket?

Ayuh,...... Rust tracks in the black carboned exhaust side of the passages,.....

whatever it is is a really bad leak and fills up crankcase and cylinder pretty fast.

Drain it, isolate the block, 'n pressurize it to 'bout 15 psi, 'n Listen,.... then follow the sound to the crack,.....

 

[alldodge]

Pull the heads and in doing so the intake comes off. This will tell you where the water is coming in.

 

[dan2744]

I didnt winterize this, I wish I would have. Im gonna take the head off tomorrow and look for a crack. I picked this up cheap and will put in another 350 if I have to. I have never seen a cracked block or head gasket leak this bad and fast. Its a pretty major leak. My leak down tester has a bad regulator or I would have done that already. Compression is 170's for all 8 cylinders.

 

[Scott Danforth]

I didnt winterize this,

may be toast.

 

[dan2744]

Can identify this motor in order to find a match? There is a plate by the starter that says its a serial number and the number was A485607, is this the engine serial number or outdrive? I appreciate the help Scott and I think I can pick up a 350 pretty cheap as long as I can match up the bolt pattern and flywheel, thanks to Bondo's help.

 

[alldodge]

The serial number (is motor number) is between 82 and 86

 

[Scott Danforth]

1986 and newer blocks will have center bolts on the valve covers and 2-piece RMS crank
1985 and older will have perimeter bolts on the valve covers and 1-piece RMS crank

what is the block casting number (starboard side, where flywheel housing bolts, just behind the head)

 

[dan2744]

I have perimeter bolts but this link is what confuses me, https://bpi.ebasicpower.com/faq/gmsmallblock.htm.

 

[Scott Danforth]

What is the block casting number

 

[jimmbo]

What does the oil look like? Oil, or coffee with cream?

 

[dan2744]

Coffee with cream for sure.

 

[dan2744]

I did a cylinder leak down test, it's showing a massive head gasket leak at the #8 cylinder, water came out from underneath it. The stamp on the block says 14010207 which says it was made in 85 and should be the 2 piece rear crank seal if I need to replace the motor. I'll have head off later to see the damage. The cylinder was at top dead center which means both valves closed, air shot out gasket area. The gasket is looks factory and puts it at 33 years old, so hopefully this is my only major problem.

 

[dan2744]

Pulled heads, block cracked real bad on both sides. Why would somebody spend 13 grand on a boat and not winterize it several months after purchase?

 

[Bondo]

Why would somebody spend 13 grand on a boat and not winterize it several months after purchase?

Ayuh,.... Ignorance, the lack of knowledge,.....