water in sump

[BobHorn]

Had boat hauled. Oil level good. 15 minutes out, overheat alarm, very little water in exhaust. Towed to marina. Today, ready to replace water pump">raw water pump, sump full of water. Raw water impeller was good, must have been airlock in strainer. Pumped out 2 1/2 gallons of water and now oil level is back at add level. How did the water get into the sump? Engine ran when we moved into the slip. Seems to be locked up now.

[Lepke]

Probably the pump shaft seal. While the raw water pump pressure is low, it's higher than the gear train that usually drives the pump. It can move a lot of water into the engine in a short time.
If the engine is locked, the rings are probably rusted to the cylinders from sitting. Bearings will also probably show wear from poor lubrication. The rings can be broken loose, but the engine will probably have lower compression and may burn oil. The engine could still have a lot of life, but with issues.

[FPNC]

Look at the exhaust as the culprit and as soon as possible. You may be hydro locked. Bad vented loop? Bad exhaust design? Bad mixer elbow?

[Reefmagnet]

Having been a "victim" of something similar, clues are there that the water pump has failed. The loss of cooling water indicates a failed impeller which would allow more water to reach a failed seal and - as I learned the hard way - if the water seal on the pump fails you can almost guarantee that the oil seal has failed as well. This lets water get into the engine via the PTO drive.


I suspect the impeller failed because of an air lock on launch, which maybe also caused the seal to fail. If the crankshaft has been soaking in water for a while, a strip down and repair will be needed. Otherwise, remove the water pump and inspect for damage from water intrusion into PTO drive of the engine to assess the level of possible damage.

[Thumbs Up]

You mean the sump below the engine I assume. Not the oil pan right? Was it seawater in the sump or engine coolant? Because if you overheated you could lose all of your engine coolant and it would end up in the sump (assuming no expansion tank). How much time passed from when you moved it to the slip until now? Days, weeks, years? Got lots of experts here that want to take a guess so more information will be helpful.

[BobHorn]

Water was in the oilpan. Engine coolant seemed good. There is a drip hole just past the pump so there could not have been enough pressure buildup to force raw water into the engine at that point. Pump impeller was in good shape. Engine ran fine till overheat alarm. Ran fine again after cooling down, maybe five to ten minutes to get into the slip after getting towed to the marina.
Thought about the oilcooler, but oil pressure would be much higher than the raw water pressure, I would think.

[BobHorn]

I was able to turn the engine over for four revolutions using a big wrench.

[jamhass]

Bob:

Sorry to hear your troubles. No solution, but perhaps an explanation as to the cause:

A friend had a similar issue. A rebuild of his raw water pump left a damaged seal installed on the raw water side. His particular pump had a very small drain hole between the water and oil seals. The bad water seal allowed a relatively slow leak that went unnoticed. Eventually, salt occluded the drain hole and salt water was forced past the oil seal into the sump. Remember, the raw water pressure is much higher than the pressure in the sump, and the oil seal is designed to keep oil in, not water out. In his case, he ended up replacing the engine.

This is a caution to all who have too small drain holes in their raw water pumps. In my friends case, overdrilling the drain hole could have saved his engine.

[Thumbs Up]

Sounds like the engine was hydrolocked (at least one cylinder full of water). My guess is overheated due to low water flow from airlock or blockage and then hydrolocked from raw water siphoning in past impeller due to a blocked off or clogged anti siphon vent (the "vent" for the vented loop. The first thing to do is get all of the water out of the engine, change the oil, run the engine to operating temperature then change the oil again and again (Assuming that you were able to find and correct the problem)

[Reefmagnet]

Originally Posted by BobHorn

Water was in the oilpan. Engine coolant seemed good. There is a drip hole just past the pump so there could not have been enough pressure buildup to force raw water into the engine at that point. Pump impeller was in good shape. Engine ran fine till overheat alarm. Ran fine again after cooling down, maybe five to ten minutes to get into the slip after getting towed to the marina.
Thought about the oilcooler, but oil pressure would be much higher than the raw water pressure, I would think.

Never make assumptions. These can turn out to be expensive. PTO connection to water pump of engine with slow dripping leak from pump weephole...

[BobHorn]

There are two big slots just past the pump, both are wide open, you can look through them and see the shaft. Sequence of events, picked the boat up at noon on Wednesday. Oil level just above add oil level. Noticed very little water from exhaust. Overheat about fifteen to twenty minutes later. Towboat arrived about 45 minutes later and towed us into marina. At that point dropped the tow, started the engine and motored to our slip, probably no more than five minutes. Thursday morning pulled the raw water pump and decided to take it home. From that point till now there was no connection to the raw water inlet. So all that water got into the oil pan between Wednesday noon and Thursday morning with probably less than thirty minutes run time.

[Thumbs Up]

Back to my questions. Could it have been coolant (antifreeze or water), Is the engine low on coolant? (assuming you have a system with a heat exchanger). Could be a bad head gasket caused by the overheat. How did the boat run before the haulout? Did it freeze there? Was any work done to the exhaust system? The oil being above the full mark sounds a little suspicious. Oil floats on water and would have been pretty separated after time on the hard meaning that it wouldn't look like a milkshake just high oil level on the dipstick.

[BobHorn]

Coolant level is good. No freezing temps. No work on engine, haulout for bottom job. Oil level good when leaving yard. Engine seemed to run fine after tow to marina. Ran maybe five minutes to get into slip. When I pumped out the sump there was a definite separation between water and oil. I'm thinking oil cooler. Have it off to take home and pressure test.

[BobHorn]

Just to close this out.
May have at least part of the answer. There is a tee in the line from the seacock to the strainer with a ball valve connected to it. The other side of the valve is a hose which disappears into the bowels of the boat. Turns out that that hose is tied into the fresh water system. At the dock we connect to the water on the dock, hence the flow from the strainer when I removed the connection to the pump. Boat is relatively new to us and I had never investigated the purpose of that valve.

So here is what I figured happened, that valve was closed until the yard put the boat back in the water, somebody opened both the seacock and that valve. Reason for the overheat, the dock water line was just lying on the deck so the raw water pump was sucking air through that valve.

When we got to the dock and connected to the dock water, that valve being open, put dock water pressure on the raw water pump and water leaked through the pump until I closed the valve when I removed the pump the following day. This would have been from about 3:00PM till 9:00AM the following morning. Once the water got past the pump, I´m still not quite sure how it ended up in the oil pan. Only two choices, I think, leaking oil cooler or through the exhaust, open exhaust valve and past the rings. Turned engine over manually four revolutions so there does not appear to be any water in any of the cylinders.

Have the oil cooler here at home and will get some fittings to do a pressure test. Had hoped to turn the engine over with the starter and the engine stop pulled, but the started solenoid exploded, so a project for next week.


Oil coller checks out good. Talked to the PO's wife, he is no longer with us, he put that fresh water connection in to be able to flush the exhaust system with fresh water, I assume with the engine running.

[FPNC]

The amount of water that came into the pan was a lot. More than can get by the water pump seal with out you noticing a leak from the pump.

It is not uncommon at all to fill the exhaust system and flood the engine through the exhaust. Particularly with the water pressure from the dock applied as you describe.

Check the oil cooler, but if it is just a transmission oil cooler, any leak in that cooler would put water into the transmission. Not the engine.