How to disect cause of hydrolock?

[TxHorns]

So my engine is suffering from hydrolock. it's a 1992 140hp Johnson. I have it at the shop right now and the guy its currently with is both good and trustworthy in my opinion. He says it could be a number of things that could have caused it, and if its something as small as a hole in the block he may never find it. It's starting to sound like this could get expensive quickly, which is even worse if I spend money and they can't find the problem.

I'm trying to get familiar with this problem - What are the most common causes? Any advice on next courses of action? Could this require a full rebuild? Thanks.

 

[Chinewalker]

Re: How to disect cause of hydrolock?

Last motor I had that hydrolocked ended up needing carb rebuilds. The float needles were worn and when the gas tanks warmed up and pressurized a bit when the vents were closed, the pressure forced fuel past the float needles into the motor... Motor was a 1982 Johnson 70hp.

 

[TxHorns]

Re: How to disect cause of hydrolock?

It's actually water that is getting in the cylinder, its not from fuel. We can tell because one of my spark plugs which is less than 10 hours old already looks a bit corroded... the shop verified it.

This also reminds me of another question, if compression tests are OK, does this rule out a cracked head? Does it rule out any other things? Thanks.

 

[cajuncook1]

Re: How to disect cause of hydrolock?

I am certainly no expert, but sometimes the simple things are overlooked.

Have you checked compression on all 4 cylinders?

Is there a possibility that the head gasket, on side of the corroded spark plug, is leaking or compromised. Water maybe entering the cylinder and causing pre-detonation and damage to the spark plug. Just a thought. Head gaskets are cheap and not hard to replace.

Good Luck I hope your able sort things out. There are a lot of knowledgeable guys on this forum!!

 

[TxHorns]

Re: How to disect cause of hydrolock?

yeah, checked compression and it was fine. I dont really have the skill or time necessary to fix/examine this myself so have a shop doing it, but trying to understand it as best I can.

Would compression still check out OK if the head gasket was the issue?

Also, failed to mention, the last time it gave me issues, I was running fine for about an hour, then backed off to an idle, then put it in reverse which is when it died. Not sure if this really helps with anything, but makes me wonder if it could be the exhaust system somehow.

Thanks again for the input, I'm trying learn how this stuff all works and the forum is very helpful.

 

[TxHorns]

Re: How to disect cause of hydrolock?

Water appears to e getting in only one cylinder - does this rule out the gasket?

 

[mamm7215]

Re: How to disect cause of hydrolock?

This actually suggests a head gasket

 

[cajuncook1]

Re: How to disect cause of hydrolock?

Yes, I would agree the head gasket.

cajuncook1

 

[kenmyfam]

Re: How to disect cause of hydrolock?

No harm in checking that out. Head gasket is a pretty inexpensive repair.

 

[TxHorns]

Re: How to disect cause of hydrolock?

good to know, thanks. we'll check it out and get back to you guys. thanks for the help

 

[Dukksoup]

Re: How to disect cause of hydrolock?

Twice now my 4.3 hydrolocked with water entering only one cylinder, turns out that this happened from engine '' RUN ON'' .....from NOT letting engine cool down before shutting off

 

[Silvertip]

Re: How to disect cause of hydrolock?

Was the engine ever overheated? A crack in the block lower down the cylinder wall, but still within the area of the water jacket could allow water into the cylinder when the piston is down below the crack. As the piston comes up the crack is now covered and compression in that cylinder could read normal. Removal of the head, rotation of the engine should reveal any cylinder wall cracks. If that inspection is ok, then a good look at the head gasket would be in order. it would certainly be possible that a tiny flaw in the gasket could allow water intrusion yet provide normal or near normal compression.

 

[TxHorns]

Re: How to disect cause of hydrolock?

sorry for delayed response. My mechanic suspected there was a small hole or crack somewhere letting water in that he just couldn't see. He had a used powerhead laying around at his shop so sold it to me cheap. Runs pretty well now except it acts a little weird when coming down to an idle from cruise. posted different thread on it though. Thanks for the input, was very helpful in understanding the issue.