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Water in cylinder after engine is shut off.

T

Temple2426

Member
2005 Four Winns Horizon 210 with a MerCruiser 5.0 MPI
I have had this boat for 2 months and got it at a deal because it needed a rebuild on the motor because water was in the oil. The risers and manifolds were shot and no telling how old they were. I completely rebuilt the engine ( All engine parts where thermal baked cleaned and mag checked) and replaced the manifolds and risers. It runs great! When I shut down the engine and let it sit an hour or more it fills a cylinder up with water on the 2-8 bank of cylinders.

The first time this happened was right after the rebuild. I had it on the trailer and cranked it for the first time and ran it for about 20 min. I shut it off and a few min later tried to crank it, It sounded like the battery was dead but fired off. Shut it back off again, tried cranking it again and it sounded again like the battery was dying and didn't crank. I chalked it up as a dead battery and pulled it out of the lake and went home. I put the batteries on charge and the charge was not needed. Batteries were good. The next morning I tried to turn it over in on the trailer and it was hydro-locked. Drained the water from the block,. Took the spark plugs out and had water in cylinders 2,4,6,8. 8 had the most water. I thought it might be the fact I backed it in to the lake and dropped the trailer axil off the end just barely and maybe the riser on that side was below the water line and water seeped back in.

Well I brought it with me to the lake house two hours away and put it in the water. Cranked it up off the trailer and ran it for 10 min. Shut it off for ten min. tried to crank it and it fired right up no water. I ran from the north end of the lake three miles south to our dock, tied it up and ate supper. Went back out to crank it and it was Hydro-locked again. Drained the water from the block. I pulled all the plugs and #6 had a ton of water in it and #4 was wet 2&8 were dry. I got the water out put oil in the cylinder just like before. Put plugs back in engine and it fired right up. No water in the oil.

I have now ran this engine for three hours today pulling a tube. Every time I kill the engine when we tie it up at the dock I use the single point drain system to drain the water out. If I do this it never hydro-locks. When we go back out it primes itself and off we go. It does not run hot. No oil in the water after three hours of running. What is causing this water to get in the cylinders? Any suggestions appreciated.
 
Who rebuilt the engine?

Did they use proper sealant on the head bolts?

Did you have the engine components checked for cracks, or the block too?

Did you also replace the manifolds with new manifolds or used?
 
Thanks for the reply.

I rebuilt the engine. Along with a friend we are both engine builders. I am a pre-war car machinist and builder. but build a few marine engines not many tho.

We used locktite 537 on the head bolts. Its a thread sealer.

I used a Sunnen thermal bake system that thermally cleans the block and heads inside and out water passages and oil passages. It heats it up to 500 degrees bakes all the oil and water scale to an ash. After that it then goes through a Sunnen airless steel shot blaster. It takes it down to bare metal. Its as clean as it was when it was a new casting. Then tested for cracks. I own these machines and use them daily. I test blocks and heads daily. No cracks found on the heads or blocks.

The manifolds and risers were new.
 
Temple2426 said:
Thanks for the reply.

I rebuilt the engine. Along with a friend we are both engine builders. I am a pre-war car machinist and builder. but build a few marine engines not many tho.

We used locktite 537 on the head bolts. Its a thread sealer.

I used a Sunnen thermal bake system that thermally cleans the block and heads inside and out water passages and oil passages. It heats it up to 500 degrees bakes all the oil and water scale to an ash. After that it then goes through a Sunnen airless steel shot blaster. It takes it down to bare metal. Its as clean as it was when it was a new casting. Then tested for cracks. I own these machines and use them daily. I test blocks and heads daily. No cracks found on the heads or blocks.

The manifolds and risers were new.
Click to expand...

I'm not familiar with 537, I typically use a quality thread sealer (Blue Monster 76009) and I have never had an issue.

Seems like you have to have bad risers/manifolds, a thread sealant issue, a bad head gasket, a crack in the heads/block, or somehow you're getting water through the carb/intake.

Given that it's always in the 2-8 bank, you can likely eliminate water through the carb/intake. I'd double check the risers/gaskets. If those look good, I'd pull the head, look at the head gasket, and give a 2nd, thorough inspection of the heads and block.
 
Remove elbows, cap exhaust manifolds with gasket and flat plate.

Get a smoke machine and introduce smoke thru water inlet hose which comes from outdrive to on engine water pump inlet.

Remove flame arrestor and hold open choke butterfly, Either remove valve cover or pull "pcv" from valve cover and then smoke it. See if and where smoke comes out from.

No mention of machining heads or deck or magnifuxing heads or block prior to reassembly?????
 
As mentioned in post #1 I have a 5.0 MPI not a carb engine.

Thanks 390express, I was not aware that Locktite 537 was not a quality sealer. I will look into Blue Monster 76009.

kghost, post #1 I mentioned that I cleaned and mag checked all engine parts. As an engine machinist my definition of a "complete rebuild" is the things you mentioned above and more. Unless these are done or at the minimum checked for serviceability its a halfway job not a complete rebuild. I understand where you are coming from tho as I have read through a lot of post and my definition of complete rebuild is not the definition of others who use the same term. Great idea on the smoke!
 
Mercruiser stopped selling perfect seal, now I would use either Loctite 1525607 or Permatex 80017. Both classified as Aviation sealant

With that much water and with it happening on a hose I would suspect the intake gasket.
 
Stopping your boat too fast will cause the stern wake to slap into the transom. If your flappers are not working correctly in the exhaust tubes, then water can get into the engine from the force of the stern wave. You probably know this but I thought a reminder would be useful.
 
zellerj said:
Stopping your boat too fast will cause the stern wake to slap into the transom. If your flappers are not working correctly in the exhaust tubes, then water can get into the engine from the force of the stern wave. You probably know this but I thought a reminder would be useful.
Click to expand...
Reminders are always good thank you so much.
The problem seems to be after stopping the boat, engine off for a length of time with water still in the block when I come out 20 to 30 minutes later, there’s water in the cylinder and it will not turn over. As long as I drained the block after using it, there is no issue with water in cylinders. It’s got to be a cracked head, (even though I checked them ) gasket issue or a bad riser/exhaust manifold (even though they are new). When I get home after vacation this weekend, I will tear into it and let you guys know what I find.
 
Temple2426 said:
Reminders are always good thank you so much.
The problem seems to be after stopping the boat, engine off for a length of time with water still in the block when I come out 20 to 30 minutes later, there’s water in the cylinder and it will not turn over. As long as I drained the block after using it, there is no issue with water in cylinders. It’s got to be a cracked head, (even though I checked them ) gasket issue or a bad riser/exhaust manifold (even though they are new). When I get home after vacation this weekend, I will tear into it and let you guys know what I find.
Click to expand...
Temple2426 said:
Reminders are always good thank you so much.
The problem seems to be after stopping the boat, engine off for a length of time with water still in the block when I come out 20 to 30 minutes later, there’s water in the cylinder and it will not turn over. As long as I drained the block after using it, there is no issue with water in cylinders. It’s got to be a cracked head, (even though I checked them ) gasket issue or a bad riser/exhaust manifold (even though they are new). When I get home after vacation this weekend, I will tear into it and let you guys know what I find.
Click to expand...
Had similar problem on my 4.3 mpi. First I thought about flappers and they where not in good shape ao replaiced them but after that still had water in cilinders amd even in oil.
Took it apart and find that my intake manifold had cracks 🫣
 
you seem to have water on the even numbered bank of cylinders so here’s what I might try. Remove that starboard side exhaust manifold & elbow as a unit. Prop it up level and run water thru it and heat the manifold with a heat gun to simulate the engine running. Then let it cool & watch the exhaust poets that match up with the exhaust ports in the cylinder head. Do you see water? If so it could be the manifold/elbow…if not, then you have to think about re-doing some of the engine work.

I had to do a similar job but less involved, I had blown HGs & a bit of water in 2 cyls, prob the result of a bad overheat a few years before that. I replaced the cyl heads with reman units, used Fel Pro Marine head gaskets & Aviation Gasket sealer on the head bolts, which I replaced with ARP head bolts. That was 7 years ago, since then no water in cyls or oil….
 
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