Water in Cylinders on a 5.0 Mercruiser

[sidthekid]

I'm hoping you guys can point me in the right direction to solve this problem. I have 1991 Bayliner 2651 that fried the water pump. I drove the boat at 6 mph for about 2 miles before I discovered the engine overheating. It overheated to the point that it was smoking around the block. It didn't get hot enough to start hearing popping and pinging sounds as in a severe overheat. Shop put in a new waterpump and test drove the boat. I picked the boat up and it was running fine. I made it through the 6 mph zone, about a mile, and then opened her up. Everthing was fine. Slowed down for another speed zone and it was fine. Opened her up again and no power. Would not plane out. The engine just sounded rough. Put her in neutral and she died and would not restart. Got her to my lift and pulled the plugs and found water in all port side cylinders and a very small amount in one cylinder on the starboard side. Pumped all the water out and tried to fire her up. No dice. Pulled the plugs again and more water in the port cylinders. Pumped the water out again and this time waited before I put the plugs back in. After a few minutes I hit the starter and more water was in the cylinders. I repeated this process and even though I pumped the water out more would come in. So my question is how did the water get in the cylinders in the first place? Could the shutters have burned out? The shutters on this model look to be under the coupler and I'm not sure how you would get to them to replace. Second question is where is the water coming from when the boat is just sitting on the lift, with the outdrive in the water of course. Can the water make it's way into the engine without it running? I hope I have provided enough details. Thanks in advance....Sid

 

[wellcraft-classic210]

Re: Water in Cylinders on a 5.0 Mercruiser

Head gaskets, cracks in head(s) or the block /cracks in the water cooled exhaust manifolds all are possibilities.

You may want to try pressure testing your cooling passages by blocking off entery & exit points on the engine / if that passes check the exhaust manifolds.

Hoping others on this site may have more experience on this and have something to add.

Good luck

 

[NHGuy]

Re: Water in Cylinders on a 5.0 Mercruiser

Maybe when it went hot you lost the seals on some of the cooling components. Since the port side is always the issue you could narrow your inspection down to those pieces.
Perhaps the port riser, manifold or gasket is the main issue. Do a fussy inspection over there.
Check to see if the riser bolts are still tight, they operate at a fairly low torque of 30 ft lbs. IF they are loose, water can fall right down the exhaust into the combustion chambers causing your hydro lock.
Happened to me this spring. Port side cylinders #'s 5 & 7 holes went hydraulic on my motor when I reused the gasket- a big no-no, then over torqued my riser. The gasket has a coating of graphite that's a couple of 64s of an inch thick, (it feels kind of like the crayons I had as a kid) If yours has any gaps where water could go through that's your issue. You might be able to just replace and carefully torque the gasket.
If it's that make sure the mating surfaces are nice and flat.
I see you are in MD, if you are a salt water boater there is a possibility that the water jacket in the riser or manifold has corroded through.
You can pressurize it to find the leak, or you can do a block off and fill with acetone or water to see if the water jackets leak down. Then you will know what to correct for sure.

 

[rschap1]

Re: Water in Cylinders on a 5.0 Mercruiser

You may get "lucky" as I did last summer.
My exhaust riser gaskets went first and just let water back into cylinders through exhaust ports.
The risers grew so much when hot that they stretched their bolts and let the gaskets loose.
It was not a bad job and fairly inexpensive...well compared to blocks, heads, and or manifolds...
Best of luck

 

[sidthekid]

Re: Water in Cylinders on a 5.0 Mercruiser

I'll pull the riser and manifold and inspect them and report back. I'm still not sure how the water travels up the leg and gets into the cylinders with the boat sitting on a lift with just the out drive in the water. Can someone explain this to me?

 

[Bt Doctur]

Re: Water in Cylinders on a 5.0 Mercruiser

A Alpha has a impeller in the drive, turn the motor,turn the driveshaft ,turn the pump.
remove the water inlet hose going to the therm housing and tie in a safe place.
drain the engine block and manifolds/risers
remove spark plugs , spin engine to remove any water
install plugs and start engine for no more than 10-15 seconds at a time.
what you are trying to do is dry everything internally. 12-24 hrs for salt, 24-48 for fresh.any longer and you have a rusted junk of cast iron.

 

[sidthekid]

Re: Water in Cylinders on a 5.0 Mercruiser

Ok, so here is the latest...Pulled the riser and manifold and they look good. Pulled all the plugs out and no water came out the cylinders when I bumped the engine over. Let the boat down into the water with it sitting on the lift but outdrive submerged. Waited a few minutes, bumped the motor and water came out the cylinders on the starboard side. After all the water was out, I let it sit a few more minutes and bumped it again and more water came out. By placing my finger over the sparkplug holes one at a time while my wife bumped the motor over it is very evident the compression in the middle two cylinders is way, way down. The oil level has risen on the dipstick so I'm sure there is water in the oil. Remember the motor overheated before all this happened. I'm thinking head gasket, what do you guys think? Not sure how the water is getting into the oil though...I hope this is enough information....Thanks

 

[NHGuy]

Re: Water in Cylinders on a 5.0 Mercruiser

http://forums.iboats.com/showthread.php?t=342393 Look at #14 & #22

 

[sidthekid]

Re: Water in Cylinders on a 5.0 Mercruiser

All apart now. Risers look great, manifolds look great. Head gasket on both heads definately blown. I'll take the heads in to get them worked over. Do I have to replace the lifters because they have milkshake oil in them or should I just change the oil a couple of times before hard running?

 

[NHGuy]

Re: Water in Cylinders on a 5.0 Mercruiser

I think you can reuse the lifters, but maybe change em if you have the dough.
I'm dealing with water in the oil too right now. I can't understand how it got in. I found a cracked outer water jacket on an exhaust manifold which I changed, maybe that allowed the motor to run too hot even if the exhaust didn't have water in it. That could cause a head gasket problem.
I have changed my oil 3 times & it's still a little milky, but at least the oil isn't rising from use. I tried to test my compression but the POS tester they rented me would not work. I think I am going to buy a real one.

 

[wellcraft-classic210]

Re: Water in Cylinders on a 5.0 Mercruiser

I have heard of people mixing 50% Kerosene or Automatic transmssion fluid with the first round of motor oil & running at idle for 10 minutes before changing the oi & filter again to help clean out the crud.

Never had to do that myself-- perhaps others can add to this based on exerience.

 

[ricohman]

Re: Water in Cylinders on a 5.0 Mercruiser

If the oil isn't a milkshake you would be ok with just an oil and filter change. Pull the lifters apart and dry them if you think they have water/oil inside them.