Water in middle cylinder

[Ebrooker007]

I have a 2002 mercury 90 hp two stroke. I rebuilt the motor this past winter and took in out in the spring and it ran great. I haven't taken it out in a few months so I took it out yesterday. The boat ran great for a while and I thought but then it would not rev past 4000 rpms. So I thought maybe I had fouled a plug or something. So when I took the plugs out the middle cylinder had some water in it. Then I run a compression check. It showed 115 on the top and bottom cylinder and 75 on the middle cylinder. I also have not run it hard since the rebuild. I used the break in procedure I found on here.

I think it is something bad but is it possible it is just a seal and maybe I wont have to tear the motor down completely again. I'm worried the block might be cracked. I did have a boat machine shop hone the top and bottom cylinder and resleeve the middle cylinder. Anybody have any thoughts as to what might be wrong.

 

[Ebrooker007]

Re: Water in middle cylinder

I guess my question is. What different ways can water be getting into the middle cylinder? I have heard cracked block and another was faulty reed valves but I don't know how water would get in that way. If someone could explain that would be great. I think water getting in causes the engine to fail in the first place.

 

[Faztbullet]

Re: Water in middle cylinder

If compression is only 75 that cylinders already damaged again and water can enter thru faulty exhaust divider plate.

 

[Ebrooker007]

Re: Water in middle cylinder

Are you saying a faulty exhaust divider plate possibly caused the cylinder damage or the cylinder damage caused the exhaust plate damage?

 

[emckelvy]

Re: Water in middle cylinder

Are you saying a faulty exhaust divider plate possibly caused the cylinder damage or the cylinder damage caused the exhaust plate damage?

A leaking exhaust manifold gasket or perforated inner exhaust baffle (divider) plate can spray water into the cylinder, causing damage.

Probably a real good ideal to pull the manifold cover/divider and inspect the exhaust side of #2 piston. You'll be able to get a better idea of what you're up against.

It's also very suspicious that it's a problem with #2, after the shop re-sleeved it. Although unlikely, there's a possibility the sleeve could be leaking.

I understand that the cylinder is integrally cast, and when they do a sleeve the old liner is bored-out or pulled out; but there's always a possibility that a porous block casting or machining error has opened-up the block to a leak that seeps thru the machined area around the sleeve.

So, when you pull the exhaust manifold, take a real close look at any water spray patterns, which may help you figure out how the water's getting in. Maybe post a few pics when you get it apart.

HTH.........ed

 

[Ebrooker007]

Re: Water in middle cylinder

I pulled the exhaust cover and can't figure out where the water is getting in. It got dark outside and storming so I will look at it again tomorrow. The cylinder wall didn't look scored but I was using the flashlight on my phone. Also the rings looked good from what I could see. Is it possible that my water leak is also my compression leak?

 

[Ebrooker007]

Re: Water in middle cylinder

Also how do you post pictures?

 

[TD_Maker]

Re: Water in middle cylinder

Have a good look at the exhaust cover gasket and the divider plate gasket. Also, when you rebuilt the engine, did you torque the exhaust plate bolts in the correct order? There is a definite pattern to follow. You MAY have cracked the divider plate.

 

[Ebrooker007]

Re: Water in middle cylinder

Yes I torqued them according to sequence in the manual. The only possible ways that water could get into the middle cylinder, that I know of, is faulty/poor installation of the exhaust gasket or a cracked block. Is this correct?

 

[Ebrooker007]

Re: Water in middle cylinder

Does anyone know where I can buy a used block or a reputable place to buy a used powerhead or engine? At this point maybe even a remanufactured powerhead?

 

[Ebrooker007]

Re: Water in middle cylinder

Could anyone tell me which year blocks interchange with my engine?