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I have been trying to resolve a leak for the last few months. I have water in the oil and oil in the cooling system. I have separated the power unit from the engine holder twice. I eliminated the power unit as the source, (at least under non running conditions) by creating a seal at the water jacket and exhaust port and sealing off the thermostat housing. Then I pressurized the water jacket and did a leak down test. No leaks on either bank. The first time, I found a leak around the drive shaft seal. Put everything back together installing all new gaskets and seals and torqued to specifications following the service manual instructions. I still had a small external oil leak but thought the water in oil problem was solved after three trips of about 20 miles each running up to about 4200 RPM. The next trip I ran a little faster for about 25 miles slow and fast, and found water / milky substance on dip stick.
The external oil leak was from the upper engine mount oil seal cover lower seal in front of the drive shaft. I found a service bulletin indicating that there has been a redesign of the cover and driveshaft seal, so I installed the new parts. This also requires a new upper mount cover which I installed. I put everything back together with all new gaskets again and following service manual instructions. I reasoned that where the oil was getting out when the motor was off and tilted up, likely was where water was getting in while running. I could find no problems anywhere that oil and water were separated by a seal, gasket or casting. I ran the motor at the dock on high idle and got a small oil sheen of the water. After flushing the cooling system with salt away a few times, the sheen still returned the next day. I then ran the boat at about 3500 rpm for about 2 miles and found water on the dip stick.
This appears to be a new problem, since it is worse than before and I know that I already fixed two oil leaks, one into the cooling system and one external. If the oil leak is not in the power unit, it is at very low pressure since all of the pressure from the oil pump is in the power unit and from there drains back into the sump. The oil leaks into the cooling system when the motor is not running and tilted up (or there is residual oil in the cooling system that did not get flushed out). I don’t know about not running and full down. I also don’t know if the water leaks into the oil only while running but I think it does while flushing. I bought an inspection camera from harbor freight that I was hoping that I could put into the dipstick tube while running water through the flush port. The camera is too big to fit in the dipstick hole, even with the tube removed. At this point, I have not yet torn the motor apart for the third time. I would like to find a way to tell where the leak is before opening it up if possible. I have been looking into putting UV die either in the oil or the cooling system so that when I open it up I can find the problem. I am concerned that if I put the die in the oil, the water will wash away the die when running the engine. If I put it in the cooling system I need a way to re-circulate the cooling water so that I don’t dilute the die too much. I can’t easily do this without putting the motor on a stand. I can’t put the boat on a trailer. I have read all the related posts especially Egorena's on the 140 oil in water.
The external oil leak was from the upper engine mount oil seal cover lower seal in front of the drive shaft. I found a service bulletin indicating that there has been a redesign of the cover and driveshaft seal, so I installed the new parts. This also requires a new upper mount cover which I installed. I put everything back together with all new gaskets again and following service manual instructions. I reasoned that where the oil was getting out when the motor was off and tilted up, likely was where water was getting in while running. I could find no problems anywhere that oil and water were separated by a seal, gasket or casting. I ran the motor at the dock on high idle and got a small oil sheen of the water. After flushing the cooling system with salt away a few times, the sheen still returned the next day. I then ran the boat at about 3500 rpm for about 2 miles and found water on the dip stick.
This appears to be a new problem, since it is worse than before and I know that I already fixed two oil leaks, one into the cooling system and one external. If the oil leak is not in the power unit, it is at very low pressure since all of the pressure from the oil pump is in the power unit and from there drains back into the sump. The oil leaks into the cooling system when the motor is not running and tilted up (or there is residual oil in the cooling system that did not get flushed out). I don’t know about not running and full down. I also don’t know if the water leaks into the oil only while running but I think it does while flushing. I bought an inspection camera from harbor freight that I was hoping that I could put into the dipstick tube while running water through the flush port. The camera is too big to fit in the dipstick hole, even with the tube removed. At this point, I have not yet torn the motor apart for the third time. I would like to find a way to tell where the leak is before opening it up if possible. I have been looking into putting UV die either in the oil or the cooling system so that when I open it up I can find the problem. I am concerned that if I put the die in the oil, the water will wash away the die when running the engine. If I put it in the cooling system I need a way to re-circulate the cooling water so that I don’t dilute the die too much. I can’t easily do this without putting the motor on a stand. I can’t put the boat on a trailer. I have read all the related posts especially Egorena's on the 140 oil in water.
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