Need Diagnosis help!!! Water in #6 cylinder

[unreel]

I have a 1985 Sea Ray 250 new to me. It has a mercruiser 260 FWC. I am going through doing a tune up before I put it in the water. I am running on ear muffs. The engine sounded good at higher rpm but at low rpm the engine would surge. Occationally off and on I would hear what I would call piston slap or something not firing. I was suspect of the #6 cylinder when I pulled the plugs cause to me it looked like water on the plug along with some oil fowling. So after the new plugs were installed I pulled the #6 plug while running and the engine did not skip a beat. So I pulled the plug and found water on the new plug. I installed new water shutters cause when I test drove the boat I could hear them slapping the y-pipe. The new shutters I put in seem to be tight fitting and seem to somewhat stick closed. The shutters do not close comepletley either? Could I get water backing up from those shutters into the engine? Or will the pressure from the exhaust blow and keep those open? I sanded the inside of the pipe to allow the shutters to be smoother but they are still somewhat sticky. Also I have evidence of water leakage at the base of my risers? Is this an indicator that the gasket could be shot and I may get water into the exhaust from there? Or do I have my garden hose turned up too much and somehow getting excess water in the engine? On another note it seems like I have what I call steam comming out of my vent tubes from the valve covers to the flame arrestor....Is that normal?........ I am at witts end I need help anything please....

Andy

 

[Haut Medoc]

Re: Need Diagnosis help!!! Water in #6 cylinder

How old are the manifolds?.....
You need to pull the riser on that side & inspect the mating surfaces.....
There should be 1/4" of good metal on allsides......
Check the surfaces for trueness with a straightedge......
Any rust in the exhaust cavity indicates gasket/mating surface failure....
I think you most likely need a new riser/manifold.....
Usually when one side goes, the other is not far behind......​

 

[Maclin]

Re: Need Diagnosis help!!! Water in #6 cylinder

If you have to winterize where you are at is this the first run-up since it was winterized?

Is this a salt water boat?

Have you looked at the oil level and condition on the dipstick?

The signs of water leakage at the riser joint make that a suspect area for leak back water intrusion into the engine via open exhaust valves when not running. Water getting in that way while running usually means something is probably cracked or rusted thru somewhere.

The hose water pressure usually is not a factor, especially if only on muffs.

I am not sure about the sticky shutters being a factor, but how much exhaust and water is coming out and where at the back of the boat?

 

[unreel]

Re: Need Diagnosis help!!! Water in #6 cylinder

This is a freshwater boat. I have exhaust comming out of the prop and the 2 ports at the transom. I have 0 evidence of oil on the dipstick. I will check the risors tonight. I should be able to look doen into the exhaust manifold from there right?

 

[Maclin]

Re: Need Diagnosis help!!! Water in #6 cylinder

By "I have 0 evidence of oil on the dipstick" I hope you mean the oil on the dipstick is clear and at the right level!

When was the last time the boat ran well with no symptoms for any length of time? I think we need a little more details on the chronology of events to be able to eliminate any factors. I don't know where you live or where you keep you boat during winter. If this is the first time running it after a winterization layup then there are other things to worry about with those symptoms (steam venting, water in cylinders,etc.). If the oil is foamy or milky then the block could have cracked over the winter and water is getting into the crankcase and is vaporizing and coming out the valve cover vents. The exhaust manifolds could have cracked as well and this caused the riser joint to be comrpomised and more. That is why I was asking about the winter treatment and if this is the first time it has been run any since any layup during freezing weather conditions.

If it has been running ok this year already and these are new symptoms then it is probably what Haut Medoc posted about, his post was not there when I typed in my first post.

Now, if you really have NO oil showing on the dipstick there would be a few more things to put on your "to-do" list.....

 

[unreel]

Re: Need Diagnosis help!!! Water in #6 cylinder

Sorry, I have 0 evidenve of water in the oil on the dipstick. I live in Michigan and had the boat on the water to test ride it for 15min. I heaed exhaust flappers hitting the y pipe. I bought the boat, replaced the exhaust flappers. Then last saturday I took it out to try and fish. It was idling rough and at speed it seemed to be fine. So I was doing a tune up(out of the water) this week and discovered the water on the # 6 plug. Could those exhaust flappers be sticking closed on me backing the water up into the exhaust? They don't what I call 100% free play in there. If I try and push them closed they don't close all the way and stick on the side of the exhaust and with a little force they pop back open. Could this be a problem, do I need to trim these things or something?

 

[Maclin]

Re: Need Diagnosis help!!! Water in #6 cylinder

I wish I knew for sure on those flappers, but my gut feeling is they are not causing the poblem, especially if you can move them by hand at all. I am sure the exhaust pressure moves them out of the way enough and the water finds the way out with the exhaust. But when you take the riser off and water comes out then you will know the flapper is acting as a dam and is a problem.

I believe the problem area is the riser joint, could be gasket or could be corroding manifolds and/or risers.

But if you are not happy with the flapper operation then be sure to address that as well, just not as the sole participant in the water intrusion. If they indeed do not open well then engine performance would be affected at upper rpms.

 

[unreel]

Re: Need Diagnosis help!!! Water in #6 cylinder

I checked it out last night. I had good compression on all but #5 and #6 cylinders directly across from each other. My father in law tells me after he heard the engine that I have some sticky exhaust valves and those flappers are making the nocking noise that I am hearing. I am guessing that I have a combo of problems :

1: Exhaust Shutters are sticking occationally and make all kinds of racket even though the are brand new.
2: Exhaust valves on #5 and #6 are sticky and intermittantly working
3: Leaky risers that dribble water into my exhaust getting through the Exhaust sticky exhast valve.

Now that I am thinking about it. These cylinder are directly below the two risers on each side. If I do in fact have leaky risers maybee those valves got corroded by the water comming in from the riser........Speculation what do you think?????

 

[Limited-Time]

Re: Need Diagnosis help!!! Water in #6 cylinder

You know you have issues with 5&6, I'd pull the risers, exhaust manifolds, and valve covers. Have the manifolds and risers checked. And take a look at the valve stems...........................and I'd be prepared to pull the heads.

 

[Maclin]

Re: Need Diagnosis help!!! Water in #6 cylinder

Yup, what Limited-Time said....

 

[unreel]

Re: Need Diagnosis help!!! Water in #6 cylinder

There should not be any presence of water intrusion inside the the manifold and inside of the riser right? I plan on atleast pulling the risers off tonight.

 

[Haut Medoc]

Re: Need Diagnosis help!!! Water in #6 cylinder

There should not be any presence of water intrusion inside the the manifold and inside of the riser right? I plan on atleast pulling the risers off tonight.

Correct, they should be exhaust black with no rust....
Your flappers are not causing the problem.....
If there is any sign of water intrusion from the riser/manifold joint, it is time to replace them....

 

[unreel]

Re: Need Diagnosis help!!! Water in #6 cylinder

Pulled the risers and manifolds last night, here are some picks what do you think? First picture is looking into exhaust manifold at #6 cylider. If you can notice the bumps, I think those might be blow outs from freezing??? Next picture is Bottom of riser. Wall thickness on the bottom is like 3/16". Last oic is an inside shot of the riser. Opinions?? Suggestions

 

[Haut Medoc]

Re: Need Diagnosis help!!! Water in #6 cylinder

Pulled the risers and manifolds last night, here are some picks what do you think? First picture is looking into exhaust manifold at #6 cylider. If you can notice the bumps, I think those might be blow outs from freezing??? Next picture is Bottom of riser. Wall thickness on the bottom is like 3/16". Last oic is an inside shot of the riser. Opinions?? Suggestions

They are spent, replace them......