Water on top of Piston!!!

[GaBoy]

Took the spark plugs out and water came pouring out. How did it get there? Bad head gasket or cooling system? Can it be fixed or do I just buy a new engine?

 

[Bondo]

Re: Water on top of Piston!!!

Ayuh,.......
Maybe a short description of Exactly What We're talking about,....
Will make it Much Easier to give you a reasonably informed Answer.....

 

[backwater dawg]

Re: Water on top of Piston!!!

Ya-how about what make-model-year-style-what you were doing that caused you to pull the plugs-other than it didn't run-ect-ect-ect----it doesn't sound good though-Steve

 

[f_inscreenname]

Re: Water on top of Piston!!!

And after all that be prepared for a list a mile long of why and how. But being winter....

 

[TilliamWe]

Re: Water on top of Piston!!!

Buy a Brand New Engine.

 

[flashback]

Re: Water on top of Piston!!!

I guess it would be safe to ask if it were winterized?

 

[Don S]

Re: Water on top of Piston!!!

Merc service bulletin on water intrussion.

http://www.boatfix.com/merc/Bullet/01/01_13.pdf

 

[Maclin]

Re: Water on top of Piston!!!

How long had the water been in there?

 

[billbayliner]

Re: Water on top of Piston!!!

Thanks for posting that bulletin Don. It was an excellent read and should be saved as it provides many great tips on how to diagnose different intrusion issues.

It's now in my boat repair folder.

Bill

 

[Hashi]

Re: Water on top of Piston!!!

Yup...thanks, Don. As Bill said, I also made a copy for my files.

 

[egldvrbags]

Re: Water on top of Piston!!!

Thanks for posting that bulletin Don. It was an excellent read and should be saved as it provides many great tips on how to diagnose different intrusion issues.

It's now in my boat repair folder.

Bill

Bill:

I came across this bulletin AFTER I experienced hydrolock. My shorestation aft end broke, leaving my boat doing a "wheelie" with the front end about 2ft above the aft. Here's what the bulletin says:

<<3. Too much weight at stern of the boat or boat was ?beached?. The customer has to be
quizzed as how the boat was loaded or what was done just prior to the problem occurring.
It is important to duplicate what was done to the boat just prior to the customer having
the problem.
a. If the exhaust elbow height meets the specification, the water could have come in
because of too much weight being in the stern of the boat. This weight could be either
gear or people at the stern or on the swim platform while the boat was ?at rest? in the
water. Equal weight has to be placed at the stern or on the swim platform and then
recheck exhaust elbow height>>

Here's what can happen to the motor:
http://forums.iboats.com/showthread.php?t=236728

I had no idea that the angle of the boat at rest could cause water intrusion. But, it's quite obvious now looking at the height of the risers to the water line.

My mechanic says he's seen hydrolock caused by having too many cases of beer on the swim platform......go figure....at least they were having a good time.

 

[Fishermark]

Re: Water on top of Piston!!!

Don, or anyone else, can you elaborate on this part of the bulletin? (It is under the section of explaining how water can enter an engine through the valves)


[highlight]1. Ignition misfire (fouled spark plug).
a. If an engine has a spark plug that is not firing, that cylinder will act like an air compressor and it can draw water backward into the exhaust manifold. Inspect all spark plugs, wires and the ignition system to make sure this was not the cause for water in the engine. [/highlight]

I certainly am not doubting that statement, I simply don't understand how that would work.

 

[Don S]

Re: Water on top of Piston!!!

The heat, and force of the plug firing really helps in blowing the exhaust and any water nearby out of the cylinder. If the plug doesn't fire, that extra force will not be there, and over time water WILL build up.

 

[45Auto]

Re: Water on top of Piston!!!

If the plug doesn't fire, then the piston is pulled down in the cylinder with both valves closed on the firing stroke (instead of being driven down by the burning and expanding of the fuel/air mixture) by the other running cylinders. This creates a vacuum in the non-firing cylinder. When the exhaust valve opens this vacuum can pull water into the cylinder.

 

[GaBoy]

Re: Water on top of Piston!!!

It is a Merc 350/260 on a 26' Searay. It is a bad head gasket and we repaired and it is running fine. Buying a new engine is not needed and did not cost very much to replace the gasket. So fellows that was not too bad. Glad to see all the different opinions on this forum.

 

[HT32BSX115]

Re: Water on top of Piston!!!

Howdy,

If it was water on top of 1 piston a bad head gasket would be a good candidate for replacement.

If you had it over more than 1 piston I would suspect the Riser/Elbow gaskets since the water would probably be coming in thru the exhaust valves.

This is what happened to my Wonderful OMC 460. The riser gaskets leaked on both sides and had been leaking for quite some time. It acted like it was "hydro-locking" every time I started it up within 10-15 min of shut down. After an over night sit, the water leaked by the rings and it would start normally.....

In any case if you removed the heads to do the gaskets you probably inspected and replaced the riser gaskets. If you didn't, it might be a good idea to check them (if they've been there a while) before they do start leaking. It's the pits if they start leaking during the winter and you discover it next Spring!


Regards,


Rick