Lower Unit Missing Oil

[Greg]

Last spring we took our boat to the dealer to service the 90hp Yamaha engine after the boat had been unused for a couple of years. They replaced the water pump impeller, adjusted the carb and said that they had tested the engine and it was ready to go.

Last weekend we took the boat out (for the first time since servicing) for a few hours and when we got back, I noticed a bit more noise that I expected in the lower unit while flushing the cooling system. I decided to check the oil in the lower unit and discovered that there was no oil at all, only water in the lower unit!

After draining the water and putting oil in, oil came out of the water intake port a bit before coming out of the oil level screw hole.

I am new to servicing an outboard and have a few questions. First, should the dealer have noticed that there was no oil in the lower unit? Have we done irreparable damage to the lower unit at this point? Why would the oil come out of the water intake? What should I do now?

Any advice you could give is greatly appreciated.

[Hamfisted]

It's a bad driveshaft seal. The seal is located right under the waterpump at the top of the lower unit. You'll have to pull the lower unit, pull the waterpump off (and it's base plate...) and you'll see the seal under the base plate. There's no way to tell if you've done major damage without tearing the whole lower unit apart and inspecting the gear set and bearings. I would replace the seal(s) (there's two of 'em there if I remember right...) and refill with Mobil One synthetic 90w oil and see how it does. But if you see big metal shavings on the magnetic drain plug chances are high that you broke it.

You can go to www.Yamahapubs.com and order a service manual for your motor.


Mike

[Greg]

Thanks for your help. I have the Clymer (from Boat U.S.) shop manual for the engine. Is the Yamaha manual significantly different or better?

[Ken]

Greg,
Dig out the service ticket from the dealer and look to see if they charged you for lower unit oil. If so, then I would raise a stink with them -may or may not get you anywhere, but would be worth a try.
If you are going to be doing your own maintenance on your Yamaha, then get yourself a Yamaha shop manual for your particular model - it will pay for itself many times over. The Clymer is a good compliment to the Yamaha, but if I had to pick one, it would be the Yamaha.
Good luck,
Ken K

[Ken]

Mike,
How do you replace those drive shaft seals once you get to them? Any special tools needed?
Ken K

[dtmackey]

Get the lower unit pressure tested to see which seal it is and mention there was "damage" that occurred after their service due to the water intrusion. I would pressure the dealer to do this for free.

If the motor was run for a long period with water in the lower unit, you may have done some damage. As previously stated, see how much metal particals are on the magnetic bottom drain plug.

D-

[Greg]

Thanks for the advice guys! I have ordered the Yamaha manual and will take it in to the dealer to see if they will take care of us. If not, I am going to do it myself (If you want something done right, ...). Should be educational.

Thanks again.

Greg