74' Mercury 9.8 hp milky gear lube

[Tofuminator]

Changed the gear lube for years with no problem, now I put in fresh gear lube and run the motor for 5 minutes, lube comes out looking like MILK. Assuming lower unit leaks, I called some outboard shops they said the steel shafts on these are messed up and it's not worth replacing seals. Just use 105 gear lube and keep topping off.

Is this true???????????

 

[tpenfield]

It depends on which seal is leaking . Prop shaft seal is worth fixing, Drive shaft seal may be an issue with the driveshaft itself.

Merc used carbon steel drive shafts up until 1978/79 ish. Then the switched to stainless steel.

Best to take a look at the drive shaft with the water pump removed to see if there are pits in the shaft

 

[GA_Boater]

Is this a saltwater motor?

Do a pressure/vacuum test and see which seals are leaking. Speedi-Sleeves can be used to repair worn seal machining on shafts.