investigating hydrolock-350 crusader

geo-mike

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Sep 5, 2015
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EDIT--I filled the block this morning and noted water running copiously from the spark plug holes at cylinders #2 and 4 (front--away from flywheel--on left side). Did not see water coming from any of the others, so it appears the fault lies only on one side, and only 2 cylinders. Neighbor suggested compression check (I have to get a tester) and check for bent rod (how ?). Does this sound like gasket fail or a cracked head ?


Yesterday, I started the port engine (350 Crusader, raw water cooled) and noted it ran very rough, and was making an odd sound so I shut it down after about 10-15 seconds. Tried to start it several more times but the starter was not able to crank it over more than a turn or 2, then eventually not at all.


I took out one of the plugs I could easily reach and it was dry. The next one was wet, and the next also. I pulled off the risers and exhaust manifolds so I could get to the plugs on the outside of the engine more easily, and water came out of all 4 cylinders on that side when I took them out. So that was 6 or 7 cylinders with water. I guess the water could have gotten in when I took the manifold away from the block, but it seems more likely that the water was already in the cylinders (since it didn't turn over).

I just changed these exhaust manifolds and risers over the winter so they were essentially new. The torque on the bolts was fine. I filled one up (blocked off the outlets) and it did not seem to leak into the manifold. I also operated the boat last weekend with no indications of problems.

At this point, it seems like the engine sucked in water when I started it today (to both cylinder banks). I need some help in deciding how to proceed here, and what to look for. I've read that it may be the intake manifold or head gaskets but I'm not sure (and have never taken apart a 350 short block before). Any suggestions on how to check this out without pulling the engine would be appreciated...thanks.

PS-I checked the engine oil and it looked pristine. I cranked the engine after taking the plugs out, and that blew the water out of the cylinders as far as I could tell (and it cranked fine). The engine has not run hot or overheated. I'm going back tomorrow to WD40 the cylinders and crank it some more (left it open overnight to dry out). Any suggestions on checking for possible rod or valve damage also ?
 
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Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Welcome aboard.

Please be patient, this is a holiday weekend.

Test the risers and manifolds with acetone.

I'm guessing twin inboards? What height risers do you have? I know of a few instances where the riser height was marginal, and after a bunch of gear added, hydrolock.

Check the water that is in your cylinders. If it is antifreeze, you may have a bad head gasket or a breach. If it is raw water, its coming in through the exhaust
 

Bondo

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I filled the block this morning and noted water running copiously from the spark plug holes at cylinders #2 and 4

Does this sound like gasket fail or a cracked head ?

Ayuh,.... Sounds more like a crack, but it's gotta be torn down, 'n the problem found,....

A Machine Shop can find cracks, the gaskets usually tell their own story when ya study it,....
 

geo-mike

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Thanks all. I established yesterday that it's not the exhaust system...the manifolds and risers are off. I should note that this is a raw-water cooled engine so when I filled the block with regular water there was no coolant involved. When the block was filled, that's when water started pouring out of cylinder #2 and 4 spark plug holes. It sounds like the next step is to take off the intake manifold and then the cylinder head, but would like advice before really tearing into it.
 
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