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Oil leaking out of stern drive

F

fireguy

New member
"I have a 1978 470 alpha 1 dri

"I have a 1978 470 alpha 1 drive. I have water in the lower unit oil and when I changed it I had oil leaking out if the small water drain hole on the back near the bottom of the stern drive. What would cause this and, how is it fixed??"
 
quad seal missing /damaged. di

quad seal missing /damaged. dislodged.
shift shaft seal
waterpump base seals
upper drive shaft seal
crack in the water cavity drain.
 
"You have to drain and change

"You have to drain and change the fluid anyway, so you might as well pressure test the drive like BD says and find out exactly what is leaking. Otherwise you are shooting in the dark.

Rod"
 
"The procedure is in the manua

"The procedure is in the manual.
You need a fitting with a air valve to fit the upper vent hole. There is a Merc part available, but it can be jury rigged.
Put only about 10 psig of air to it or you will blow it up. If there is a leak that will find it.
If in doubt, put the drive in a tub of water and look for air bubbles.

Prime suspects are the lower shift shaft seal, quad o ring seal, as well as the lower shaft seal to the lower gear unit, below the water pump.

On a 30 year old drive it is highly likely that all the seals are old and tired, if original.
You may be wise to take it to a dealer and get it completely "resealed". This would also allow a full inspection of the gears and bearings.
I would get a quote first.

If the estimate is several hundred dollars (pretty likely), you may want to consider a bolt-on replacement SEI drive for $1195 plus shipping. Then you are all good to go and you can use your old drive as a paperweight or a spare.

Rod"
 
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