Puzzled - Changing lower unit oil - Yamaha F75TLR

[jcleejr]

Just changed lower unit oil on almost new Yamaha F75TLR (4-stroke). I used the same procedure that I had used on my previous engines (drained old oil, used pump in lower drain hole and watched for oil to flow from upper hole). This time there appeared to be oil coming from the water intake vent which is just below the upper hole. Can this be possible? I thought the sump that holds the lower unit oil was sealed except for the upper and lower holes. I guess it is possible that the overflow ran down the side and just "appeared" to be coming from the vent without my having noticed.

Any thoughts on this would be appreciated!

Thanks!

 

[robert graham]

Re: Puzzled - Changing lower unit oil - Yamaha F75TLR

Maybe put your pump back in lower hole and pump a few times(with upper drain plug out) to make double sure the oil didn't just come out of the upper hole and run down outside of motor. There's only 5 places the oil can get out of lower unit, the 2 drain/fill holes, the prop shaft seal, the shifter shaft seal and the drive shaft seal. I guess if you pumped oil in with the upper plug in, then you might force oil out of one of the upper seals(shifter or drive shafts). Better double check this!

 

[jcleejr]

Re: Puzzled - Changing lower unit oil - Yamaha F75TLR

Maybe put your pump back in lower hole and pump a few times(with upper drain plug out) to make double sure the oil didn't just come out of the upper hole and run down outside of motor. There's only 5 places the oil can get out of lower unit, the 2 drain/fill holes, the prop shaft seal, the shifter shaft seal and the drive shaft seal. I guess if you pumped oil in with the upper plug in, then you might force oil out of one of the upper seals(shifter or drive shafts). Better double check this!

Do you know of any way to check without removing lower unit? I placed an oil-zorb pad under motor overnight to watch for leakage and there is none.

 

[robert graham]

Re: Puzzled - Changing lower unit oil - Yamaha F75TLR

Do you know of any way to check without removing lower unit? I placed an oil-zorb pad under motor overnight to watch for leakage and there is none.

Maybe there's no problem at all...just some paranoia about the motor...

 

[jcleejr]

Re: Puzzled - Changing lower unit oil - Yamaha F75TLR

You're probably correct about their being no problem. However, in my state of paranoia and after having seen outdrives which had suffered from water intrusion, I did remove the lower unit and inspected for any visibile signs. At the very least it gave me the opportunity to inspect the water impeller and clean out a little "crud" that had accumulated. All appears to be normal. After a short test run I still intend to drain a little of the lower unit oil and visually inspect its color.

Thanks for your replies. I posted this question on two forums and yours were the only ones I received.

 

[ADK_Boater]

Re: Puzzled - Changing lower unit oil - Yamaha F75TLR

I've had the same thing happen. What I did was pump in too much oil because I was worried about losing oil when I disconnected the pump, if I didn't get the plug back in fast enough. Oil slowly dripped out for a week. It finally stopped, and I have no water intrusion in my gearcase. In my case, I believe putting to much oil in pushed it past the drive shaft seal a little and it slowly ran down over time.

Keep an eye on it though.