Hydro-lock

[inwo]

What are my chances?
Stock 350 dieseled when I shut it off. An hour later it wouldn't turn over. Thought it was the pump so I towed it without starting. It never fired, but I did crank it hard.
Never knew that could happen (run backwards). To do a thorough tear down and check everything is as much as a new motor.
Anyone ever get away with running this way?

[centerhill condor]

yes, yes I have...
here's the deal. when you say you "cranked it hard"...what does that mean?
if the cylinder was full of water and the engine didn't turn over you've got a pretty good chance of being okay. However, if the cylinder was say half full and the engine turned over and a cylinder fired successfully then stopped suddenly you could bend a rod, blow a head gasket, best case scenario you lose a tooth on the flex plate and mangle the starter pinion.
I'd pull all plugs and see if the engine will turn over. Look for water on a spark plug, and see if water comes out of a hole. compression tests would be the smart thing to do.
Getting the water out of the cylinders is key to success and time is of the essence.
Keep us posted
CC

[Moneypitt]

Where did the water come from? Surely the exhaust system has safe guards against water flowing into the motor, even if the motor runs backward for a short time. I'm with Robert on this one, did it crank and not start? or not crank at all? Either way, pull the plugs and, if possible, rotate the engine by hand to push anything in the cylinders out, SLOWLY.......Also, check the oil for signs of water and/or fuel. Just dieseling, or running on, after you shut it off shouldn't polute the engine.........Is it possible it dieseled because it was kinda HOT? That would explain the hard cranking afterwards, but it should've started later, when cooled down..........MP

[inwo]

AS far as I know it never fired. But it runs sweet, and first one up usually hits. :(
Half the holes had water. Who knows how much? It's hard to say.
By cranking hard, I mean, trying to start it. Seemed like a low battery, so I switched to another one.
When I got home, I pulled the bowl. Rotated with the impeller wrench backwards until it locked. That was the first time I thought "motor". :sqeyes:
Took out plugs and cranked. Now that I think of it, it didn't shoot a stream. Not like the time I drove my Cuda in the drink. :idea:
I wd-40ed the cylinders half a dozen times and cranked clean.
Compression is good. But so good it blows my cheap rubber tipped gauge out at 200 +.
Now the rest of the story. I have know idea what cranking oil pressure is on this motor. My big block ran over 30. Only pops up to 10 psi. cranking under compression.
I'm afraid to light it! I guess I really don't want any bad news.
And on the exhaust: This is new to me! It's a tin river boat. The exhaust goes thru transom like normal. But there is an airtight (I think) channel down to below water line. It would seem to me, that's a very baaaad idea.
The up side is, it sits high at the beach. The snail must be well over a foot above water line.

[pw_Tony]

AS far as I know it never fired. But it runs sweet, and first one up usually hits. :(
Half the holes had water. Who knows how much? It's hard to say.
By cranking hard, I mean, trying to start it. Seemed like a low battery, so I switched to another one.
When I got home, I pulled the bowl. Rotated with the impeller wrench backwards until it locked. That was the first time I thought "motor". :sqeyes:
Took out plugs and cranked. Now that I think of it, it didn't shoot a stream. Not like the time I drove my Cuda in the drink. :idea:
I wd-40ed the cylinders half a dozen times and cranked clean.
Compression is good. But so good it blows my cheap rubber tipped gauge out at 200 +.
Now the rest of the story. I have know idea what cranking oil pressure is on this motor. My big block ran over 30. Only pops up to 10 psi. cranking under compression.
I'm afraid to light it! I guess I really don't want any bad news.
And on the exhaust: This is new to me! It's a tin river boat. The exhaust goes thru transom like normal. But there is an airtight (I think) channel down to below water line. It would seem to me, that's a very baaaad idea.
The up side is, it sits high at the beach. The snail must be well over a foot above water line.
How dare you....:devil:

[inwo]

Where did the water come from? Surely the exhaust system has safe guards against water flowing into the motor, even if the motor runs backward for a short time. I'm with Robert on this one, did it crank and not start? or not crank at all? Either way, pull the plugs and, if possible, rotate the engine by hand to push anything in the cylinders out, SLOWLY.......Also, check the oil for signs of water and/or fuel. Just dieseling, or running on, after you shut it off shouldn't polute the engine.........Is it possible it dieseled because it was kinda HOT? That would explain the hard cranking afterwards, but it should've started later, when cooled down..........MP
Oil looks ok. Like new.
Closed cooling system is not low.
Motor has been running on a little since I replaced power valve in carb. It was blown and running super rich. Just hadn't got the idle set right yet. I had nooo idea this could happen from dieseling.
Boat had not been run hard, but shut off too soon at the beach. In the past it just hit a couple times. This time it hit for 10 or 15 seconds. I was already on the beach and didn't dare fire it again.
Never cranked past a full one, but might have went past a wet one. :(

[76ANTHONY]

Oil looks ok. Like new.
Closed cooling system is not low.
Motor has been running on a little since I replaced power valve in carb. It was blown and running super rich. Just hadn't got the idle set right yet. I had nooo idea this could happen from dieseling.
Boat had not been run hard, but shut off too soon at the beach. In the past it just hit a couple times. This time it hit for 10 or 15 seconds. I was already on the beach and didn't dare fire it again.
Never cranked past a full one, but might have went past a wet one. :(
did you crank it with all the plugs out? and did you use the starter to do it?

[inwo]

did you crank it with all the plugs out? and did you use the starter to do it?
Yes, I did now!
Cranks with the plugs in now. Guess I'll let er fly!

[inwo]

So far so good! Fired right up. Sound good, oil pressure came up, no bad sounds.
Test drive tomorrow. Then try to figure out a way to keep this from happening again.
Where does a backwards motor get fuel?
Had water on both sides so most likely not a leaky manifold. Water had to be sucked up over the snail. If that's the case, I guess I'll drill a "vacuum breaker" hole above the water line.
Now that I traded boats, I guess I should take it over to "river jet forum", but all the motor heads are here.
Any believers in sea foam on here? Like I said before, this motor has been running super rich, like over 20 gal/hour.(bad power valve) Could be carboned up pretty bad.
Is a rich idle or lean idle best for stopping run-on? Slower the better right? I'm at about 850 to 900 now. Remember this is a stock 350.
I'm going over to "river jets" and ask about under water exhaust.

[inwo]

How dare you....:devil:
That wasn't the worst of it. A Cuda was just a teenage valiant back in 1968.
After putting it in the drink, I took a torch to it. Made a street "altered". Moved the wheels 18" up to the back door. Put in a 440 with the old chrysler 300 long cross ram. Did wheelies on main street.:D

[centerhill condor]

if the engine runs too hot it will lead to run on. Low octane gas, improper timing, and carbon deposits all contribute to run on. I'd work on the engine a little before drilling a "vacuum breaker".
Fuel is already there due to incomplete combustion.
You got lucky! go buy a lottery ticket and see how you do!
CC

[jdf]

if the engine runs too hot it will lead to run on. Low octane gas, improper timing, and carbon deposits all contribute to run on. I'd work on the engine a little before drilling a "vacuum breaker".
Fuel is already there due to incomplete combustion.
You got lucky! go buy a lottery ticket and see how you do!
CC
good call

[inwo]

No rattles. Compression good on all cylinders. Set idle mixture for smooth idle and no run-on.
Ran and idled flawlessly through 30-40 gallons of gas.
Leaving the beach today, motor died about 100' out. :(
No fuel because no oil pressure. (electric fuel pump interlock)
Now I have no cranking oil pressure. Dist turns. No water in oil.
Any guesses?