Hi y'all, I'm new here. Brief history - I'm 39, been boating all my life, learned from my Grandpa, and now have his old boat. It's a 69 Imp. I fix all my own stuff. I read some "water in the cylinder" threads, but nothing quite matches my situation, so here goes.
- Was a Merc 165 I/O. in 2004 I replaced the Chev 250 with a 292, all nice and fresh. Used the old head (which had been worked on a couple years prior) and manifold. Also replaced the outdrive with a new Alpha1 Gen1.
- Boat ran good for several years, used infrequently (bummer).
- Last year we only took (1) 3-day lake trip. Part way through there was moisture on the dipstick. Not to the milkshake stage, just slight foam and discoloration. That's definitely the first time that had ever happened. Quit running the boat except for the very short hop to the ramp. Engine always started fine and ran on all 6 with full power that trip.
- At home I found #1 cylinder half-full of lakewater. (Why did it not hydrolock??) Other cylinders had no water. Cleaned out, oiled liberally, changed oil (drained a very small amount of water from the pan), ran boat (with cooling water hose and exhaust riser disconnected) for a minute or so to help dry out, oiled cylinders again, etc.
- After I ran it I checked compression and all were between 160-170. #1 was the lowest, but only by a couple PSI.
- Now I'm finally working on it. Pulled manifold and the marine shop pressure-checked it OK. Hmm, I really figured it was the manifold.
- Shop inspected the riser and saw no problems. He said riser problems usually fill #6, not #1 - makes sense.
- I pulled the head, hoping to find an obvious rust path at cyl #1. There is no obvious problem. Gasket looks fine, I wire-brushed the chamber and it looks fine, pulled the ex valve and the port looks good, as much as I can see, although the carbon coating the inside of port #1 does look different from the other 5, indicating that the water did sit in the ex port. There is sign of the water on the ridge at the top of the cyl and the small space around the top of the block deck between the cylinder and the head gasket fire ring, which just tells me that #1 was the only cylinder that had water. But no sign of how the water got in there.
- The cylinder wall doesn't look great - there evidence of the water sitting on top of the rings for a few days. I can't see that it is cracked or anything.
- I live in Tucson where we don't get hard freezes, only occasional light freezes. I make a point of draining the block and manifold anyway, although one winter I forgot. However, the problem just showed up last summer and I did drain the engine the winter before.
- I figure it leaks into chamber #1 (but don't know how
), then a little got into the oil leaking past the rings.
This is very long, sorry, but I didn't want to make one of those vague, "hey, my boat won't run, can you tell me why?" posts You guys have any ideas?
Thanks, Jeremy
- Was a Merc 165 I/O. in 2004 I replaced the Chev 250 with a 292, all nice and fresh. Used the old head (which had been worked on a couple years prior) and manifold. Also replaced the outdrive with a new Alpha1 Gen1.
- Boat ran good for several years, used infrequently (bummer).
- Last year we only took (1) 3-day lake trip. Part way through there was moisture on the dipstick. Not to the milkshake stage, just slight foam and discoloration. That's definitely the first time that had ever happened. Quit running the boat except for the very short hop to the ramp. Engine always started fine and ran on all 6 with full power that trip.
- At home I found #1 cylinder half-full of lakewater. (Why did it not hydrolock??) Other cylinders had no water. Cleaned out, oiled liberally, changed oil (drained a very small amount of water from the pan), ran boat (with cooling water hose and exhaust riser disconnected) for a minute or so to help dry out, oiled cylinders again, etc.
- After I ran it I checked compression and all were between 160-170. #1 was the lowest, but only by a couple PSI.
- Now I'm finally working on it. Pulled manifold and the marine shop pressure-checked it OK. Hmm, I really figured it was the manifold.
- Shop inspected the riser and saw no problems. He said riser problems usually fill #6, not #1 - makes sense.
- I pulled the head, hoping to find an obvious rust path at cyl #1. There is no obvious problem. Gasket looks fine, I wire-brushed the chamber and it looks fine, pulled the ex valve and the port looks good, as much as I can see, although the carbon coating the inside of port #1 does look different from the other 5, indicating that the water did sit in the ex port. There is sign of the water on the ridge at the top of the cyl and the small space around the top of the block deck between the cylinder and the head gasket fire ring, which just tells me that #1 was the only cylinder that had water. But no sign of how the water got in there.
- The cylinder wall doesn't look great - there evidence of the water sitting on top of the rings for a few days. I can't see that it is cracked or anything.
- I live in Tucson where we don't get hard freezes, only occasional light freezes. I make a point of draining the block and manifold anyway, although one winter I forgot. However, the problem just showed up last summer and I did drain the engine the winter before.
- I figure it leaks into chamber #1 (but don't know how
), then a little got into the oil leaking past the rings.This is very long, sorry, but I didn't want to make one of those vague, "hey, my boat won't run, can you tell me why?" posts
You guys have any ideas?Thanks, Jeremy
