Merc 225 optimax lower crank seal leak

[buzzerbaits11]

I have a 2003 merc 225 optimax and I had the hot engine buzzer go off last weekend. The engine went into safe mode from what i was told and we could only idle back to trlr. I took the boat to my motor guy and he took the lower unit off and said the lower crank seal was leaking and that is why the hot engine buzzer went off due to oil/fuel running down the shaft and then being drawn back into the engine thru the water pump. He mentioned that due to the water/oil going thru the water pump it could not create enough pressure/water flow and this is why the hot engine buzzer went off. Just wondering if anyone else had heard of this before.. Thanks

[EuropeanAM]

Lower crankshaft seal problems DO occur occassionally.

That being said... there is no avenue through which oil from the lower crank seal should be getting INTO the water pump.

MUCH more likely that the DRIVESHAFT seal in the GEARCASE is leaking... pushing GEAR LUBE into the water pump.

I've seen at least one case of a lower crankshaft seal leaking... engine ran that way for almost 2 years (and never experienced any significant problem, other than a really nasty driveshaft housing).

[buzzerbaits11]

Thanks E man..

[shermsmarine]

I agree w/ Don I don't think your tech has the correct diagnosis of the issue.. No way that much gas & oil can leak down out of the powerhead bottom seal let alone be drawn back into the water pump and cause a overheat issue.

[buzzerbaits11]

I went to check out my boat today and i believe my tech is right with his idea. The lower crank seal leaked when the engine is off. The gas/oil sits right on that seal. It leaked out on goes down the shaft to the foot. There is a rubber like boot that is around the shaft and on top of the water pump. Oil can go pass that boot and straight into the water pump. Then the water pump has oil/water around it and the rubber fins on the water pump loose force when pushing water up thru the motor. There is no gear oil anywhere only merc engine oil leaking straight down the shaft.

[Pacer]

Maybe what he is saying happened was that the oil softened, or degraded the rubber water pump impeller?? A little lube shouldn't stop the waterpump from pumping. Right? The pump doesn't depend on friction, it squeezes the water and forces it into the engine.

[EuropeanAM]

<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Pacer &raquo;</td></tr><tr><td class="quote">Maybe what he is saying happened was that the oil softened, or degraded the rubber water pump impeller?? A little lube shouldn't stop the waterpump from pumping. Right? The pump doesn't depend on friction, it squeezes the water and forces it into the engine.

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Actually, the pump DOES depend on friction. In that regard, I agree.

However... if the face seal (atop the pump) is intact, it's nearly impossible for oil/fuel coming down the driveshaft to actually enter the water pump at this location.

The crankshaft seal problem should obviously be addressed, however.

I would, however, recommend a pressure test of the gearcase (in addition to the crankshaft seal, and water pump).

[Ron H 520]

I had a 90 Mariner 200 that had a problem much as you describe. The oil/gas was leaking down the shaft, getting into the rubber impeller, and causing it to release from the shaft and not spin properly.

I first noticed it on my pressure gauge as a sudden loss of pressure below what this engine usually ran. It never overheated, but I knew this was too low of a water pressure reading( 5-10 psi vs 17-20) that I normally ran. Tech replaced the impeller, good pressue for a short time, then same pressure drop. He figured it out after about 3 impeller changes, changed the upper seal, and the problem was solved. It was a weird deal.