Frozen Block?

[Ypt14flyr]

I bought a 1987 Four Winns 16' bowrider fixer-upper (cheap) wanting to get back on the water (after 30 years), and knew the engine had probs, but being a decent mechanic, (albeit not familiar w/ marine engines), I thought I'd have a go.. The engine did show some traces of water in the oil, but not a lot. (We suspect, now, a cracked manifold. Some traces of rust in a couple intake ports, but no signs on the head gasket or on the top of the pistons).
Bigger prob.. it was spitting a firehose of water out the back, we discovered the large upper rear core plug had blown out, (And got beat to heck by the flywheel).. Now I asked several (marine) people IF that 'freeze' plug, (I know..wrong name).. could blow out WITHOUT freezing the block?? In other words.. Is it possible for that plug to come out.. for whatever reason.. and NOT having frozen and further damaged the block?.. Everyone.. to a man.. said "No Way".. Well.. I took the bare block to the very best engine rebuilder in Portland, Or., and they cleaned it, magnafluxed it and pressure tested it and I was told.. this is one of the better 3.0L blocks he'd seen in quite some time.. No cracks anywhere!.. So.. ? The exception to the rule.?
Why that plug came out will remain a mystery.. but It IS possible, I guess. (Very 'light' freeze and a loose plug..??) Naww.. The plug is so 'high' (in the water jacket), that seems highly unlikely.. In fact, in a freeze, the whole block would have to be full to the top with water, and that seems impossible, even if the block wasn't drained..?? Wouldn't it? So..?

 

[racerone]

They are " core plugs "----Mistakenly called freeze plugs.-----

 

[Lou C]

I’d say buy a lottery ticket! That’s a rare but not unheard of event!

 

[Scott Danforth]

Pressure test the cooling water jacket. The 3.0 will crack inside, just above the pan rail, however won't leak until warm

 

[Scott06]

Yes unusual but not unheard of for a core plug to get pushed out and not crack the block

If it was magged and pressure tested I would think it is ok. A neighbor had same issue because he waited until after first freeze to winterize. Put in a core plug in and seeemed like no water was getting in oil but after 3-4 uses crankcase was getting water on it. This was a different situation in that he engine never came out of the boat until water was in the oil

 

[Ypt14flyr]

Yes, I originally called it a core plug.. and it was pressure tested.. so maybe I did hit the lottery.. but the location of this plug.. very high up.. really baffles me as to how it could 'freeze' out. Anyway.. I set this block aside for my next 3.0 build. I got a decent short block from an '85 Glastream and built up a 'replacement' engine. We almost got it running today.. fuel pump seems bad, but squirting gas in the carb and it went vroom ..vroom.. nice. I left out intervening details.. ie; I quit on the 4 Winns and got an '88 Marlin 16' bowrider, cheaper and nicer, so the 'new' engine is going in that one.. Anyway, still learning about these marine engines, but like learning new things.. and I like having good luck once in a while..lol. (Although it did cost me $315 to get that 1st block checked, but understand it's worth that or more). I need a whole walk-thru windshield for the Marlin if anyone has any clues. Thanks all.. JG

 

[Scott06]

Yes, I originally called it a core plug.. and it was pressure tested.. so maybe I did hit the lottery.. but the location of this plug.. very high up.. really baffles me as to how it could 'freeze' out. Anyway.. I set this block aside for my next 3.0 build. I got a decent short block from an '85 Glastream and built up a 'replacement' engine. We almost got it running today.. fuel pump seems bad, but squirting gas in the carb and it went vroom ..vroom.. nice. I left out intervening details.. ie; I quit on the 4 Winns and got an '88 Marlin 16' bowrider, cheaper and nicer, so the 'new' engine is going in that one.. Anyway, still learning about these marine engines, but like learning new things.. and I like having good luck once in a while..lol. (Although it did cost me $315 to get that 1st block checked, but understand it's worth that or more). I need a whole walk-thru windshield for the Marlin if anyone has any clues. Thanks all.. JG

These marine engines are basically truck or industrial motors. Not rocket surgery. Biggest thing you need to watch is stringer and transom rot with the age of boats you are working on

save your receipts for the machine shop work on the 3.0. Yes it’s worth more than $315. If you have some back up documentation that it is not cracked bore measurements etc any potential buyer would pay more

 

[Ypt14flyr]

Yeah the 4 Winns had bad center floor boards. I was just going to screw a sheet pf plywood on top for a cheap way to get on the water, (It's upholstery was chewed by critters also).. (I got the 4 Winns because the engine 'LOOKED' so nice.. lol.. all rod bearings were spun and the core plug was blown out)(but that's the block that was good).. but the Marlin I picked up is reasonably sound all over.. (We knew it's engine was toast).. Except for the missing windshield, so we put the 'new' cobbled together engine in it instead. I do have paperwork for the good block.