Raw water entering back cylinder.

[Jim van Cleve]

Raw water has been entering the back cylinder on my year 2000, m25xp, Westerbeke engine, in my 1968, P35.
This was discovered during an out of boat rebuild and it's being said that this is because the Vetus water lift muffler, in the stern locker is higher than the exhaust elbow. The anti siphon loop and vetus siphon break
is higher than both, and working properly.
The cylinder 3 exhaust valve was badly pitted as was the piston face
and the rings were rusted in place.

[Captsteve53]

Water locks for engines on or below the water line are supposed to be lower than the riser height for the water to collect in as below diagrams which pretty well explain it, the second is for engines that is mounted above the water line

Cheers Steve

[DougR]

Time to find a new, lower home for the water lift muffler, or install an exhaust riser on the engine, or both.

DougR

[GrowleyMonster]

Originally Posted by Jim van Cleve

Raw water has been entering the back cylinder on my year 2000, m25xp, Westerbeke engine, in my 1968, P35.
This was discovered during an out of boat rebuild and it's being said that this is because the Vetus water lift muffler, in the stern locker is higher than the exhaust elbow. The anti siphon loop and vetus siphon break
is higher than both, and working properly.
The cylinder 3 exhaust valve was badly pitted as was the piston face
and the rings were rusted in place.

Yeah that sounds like something that needs to be corrected. But on a related note, you do keep the raw water intake closed until the diesel is running, right?

[Sailmonkey]

Originally Posted by GrowleyMonster

Yeah that sounds like something that needs to be corrected. But on a related note, you do keep the raw water intake closed until the diesel is running, right?

Nobody does that!!

This just sounds like the waterlift is either higher than the engine or at the same level as the engine.

[Captsteve53]

The water/sea cock only needs to be closed should your engine not start with in the normal cranking cycle, but yes it does need to be closed if for any reason the engine has pro longed starting other wise you can fill your water lock and eventually flood your engine through the Riser /open valve's

[roland stockham]

Also worth looking at the volume in your water separator. This need to hold the volume that may be in the pipework between the separator and the anti-siphon vent but bigger is better and acts as a check 'just in case'. A common cause of problems is salt build up in the anti-siphon vent which can be replaced by a small pipe running overboard that wont clog. Final issue can be waves. If the transom exhaust outlet and the anti-siphon vent are both on the low side a stern sea can run in and flood the system. A sea cock in the outlet turn off during storms or when leaving the boat stops this being an issue.

[jhulmer]

I had the very same problem and had to rebuild my engine as well.

I made an exhaust riser because I couldn't get the water lift low enough.

You must have enough volume in your waterlift to hold all the water in the exhaust riser and the hose up to the bend before it exits out of the hull. So the water in the muffler can't make it back to the engine at maximum heel.

See the pics of the process:

[skipmac]

Hi Jim,

Depending on your boat I may have a different answer.

By P35 do you mean a Pearson 35? Does it have a V-drive? Does the exhaust riser connect to the aft end of the engine?

if yes to these then the problem could be due to corrosion in the riser where the raw cooling water injects. Happened to a friend with a V-drive Pearson. Due to internal corrosion the water injection was higher than exhaust pipe that lead back to the engine and a little raw water would drain down into the aft cylinder.

[GrowleyMonster]

Originally Posted by Sailmonkey

Nobody does that!!

This just sounds like the waterlift is either higher than the engine or at the same level as the engine.

I know. And sometimes it comes back to bite them in the hiney. I always do. Sometimes it makes a difference. Especially if it doesn't start right up. Anyway it isnt much bother and it doesn't hurt a thing to do it.

[encore]

Very simple once you get in the habit. Start the engine then open the sea cock, stop the engine, close the seacock. Changed enough oil and filters before I got wise. It only takes a couple extra cranks and sometimes you have a mess. I printed up some instructions on bright paper in case someone else starts the engine when I'm not around. Not all engine/exhaust systems are ideal.