water in cylinders and low compression

[1993 celebrity 4.3L]

had the boat out 2 weekends ago and it ran great as usual. It's a 1993 very well kept and maintaiined boat with under 350 hours. I shut it off to infate a tube and it wouldn't start back up. Blew out the starter trying to crank it over so many times and had to get towed in. Replaced starter and it would still barely turn over. Battery checked out fine. Took it to my mechanic the other day and just got the report from him.

1. water in the cylinders
2. did compression test and one one of the back cylinders is at 90 the rest are between 125 and 135.

He is going to stick new plugs in it and try to get it to run and then diagnose from there.

Questions are:

1. What the heck could have happend that would allow water into the cylinders when it had run great all day?

2. Is the low compression a related or unrelated problem?

3. What are my best and worst case scenarios?

Of course I asked my mechanic all these questions but he's reluctant to answer yet. Anybody input would be appreciated.

 

[Don S]

Re: water in cylinders and low compression

1. What the heck could have happend that would allow water into the cylinders when it had run great all day?
Defective exhaust manifolds, risers, or both, or the gasket between them failed. Usually because the manifolds and risers were bad.

2. Is the low compression a related or unrelated problem?
Usually rust develops on the rings and cylinder walls. On salt water boats this happens in a matter of hours.

3. What are my best and worst case scenarios?
If minor rust, some oil could free up rings and possibly stuck valves.
Worst case, new engine

 

[1993 celebrity 4.3L]

Re: water in cylinders and low compression

As usual Don, you come through with a timely and informative response, thanks.
I'm just puzzled why there weren't signs that the manifold or riser was bad or going bad. I mean it didn't miss a beat the whole day until I shut it off. If the manifold or riser is bad, is it a structural thing where it's cracked or what? Any idea what kind of cost I'd be looking at for new manifold and or riser?

 

[Coors]

Re: water in cylinders and low compression

Did you do a fast stop and shut-down?
Water can come in that way.

 

[1993 celebrity 4.3L]

Re: water in cylinders and low compression

coors, what do you mean by a fast stop and how would it cause water in my cylinders? I'm not being cynical, I'm just not sure what you mean.

 

[Robj]

Re: water in cylinders and low compression

If you are travelling at a high speed, and then suddenly slow down, the wake created will splash the back of the boat, and it can also go up through the manifold and into the cylinders. That is why you should never abruptly throttle back with an i/o, or you can get water into the cylinders.

Have a great day,

Rob.

 

[Don S]

Re: water in cylinders and low compression

That will only happen if you stop quickly and shut the engine off. As long as it's running, the exhaust coming out of the engine will keep the water out of the manifold.

 

[1993 celebrity 4.3L]

Re: water in cylinders and low compression

Thanks guys. As I think back on the day we got stranded, it's very possible that I did make such a fast stop. I had just finished pulling a tuber and shut it down to pull everything in. I'm going to cross my fingers and hope that's all it is. I should be hearing from my mech. today on what he thinks.

He said one of my back cylinders has low compression. Can that just be from the water in the cylinder or is that a different problem all together? From what i've read on this forum, the compression problem could be a stuck valve, bad ring, or a head gasket issue.

Appreciate all the good advice (although not always good news)

 

[Don S]

Re: water in cylinders and low compression

Cold water hitting hot valves can warp them a little causing low compression.

 

[thrasher]

Re: water in cylinders and low compression

I had the same thing happen to my boat, stopped quickly and shut of the motor. Then found I had water in my cylinders.. The thing that I asked myself is how can water get in the cylinders when there is a non-return valve in the exhaust (Flapper valve). I checked and one of my flapper valves had collapsed and dropped down the inside of the exhaust. I would get you mechanic to check that the flapper valves are present and also not stop quickly and kill the engine as suggested earlier.. Water in the cylinders was the sympton not the cause!!
I hope there is no major damage to the engine and you are up and running very soon.

Gary

 

[1993 celebrity 4.3L]

Re: water in cylinders and low compression

Thanks Gary. My mech. mentioned something about the flappers possible being bad but I'm still waiting for the call from him on his diagnosis. I'm nervous to say the least. Anyone know how big of a deal it is to replace it/them?

My wife told me this morning that if divorce court is cheaper then fixing my "damn" boat, I might want to go that route. Anyone know a good lawyer?

 

[1993 celebrity 4.3L]

Re: water in cylinders and low compression

OK. Got the dreaded news yesterday from my mech. He got the boat to start and run with new plugs after drying out the cylinders. He put the boat into the water and ran it for about 5 minutes without problems. Then he said it started hammering real bad (sounded like a diesel engine) He pulled the oil and found about a gallon of water.

He's suspecting a cracked head. However, he did a compression check and all the cylinders had excellent pressure.

Question is, can the head be cracked or compromised in some way and still pass a compression test with flying colors? What else can be allowing the water into the oil?

 

[Flukinicehole]

Re: water in cylinders and low compression

Yes head can be cracked and it can still have good compression. There is a big cylinder full of air trying to get out of the little crack so you will still have good compression. Have him do a leakdown test or just pull the heads and have them magnafluxed. A gallon of water after 5min is alot.