Mercury 50hp lower unit - Water tube?

[aarrjimlad]

Hi

Your help with the following would be much appreciated.

I have recently purchased a 1982 4 cylinder Mercury Blue Band, and have removed the lower unit to check the impeller. At the front of the unit there is a ?water tube? that has broken away from the plastic securing nut/gland, this I can repair. However what is the purpose of this tube, it?s sealed at the upper end?

Additionally why does the Clymer manual specify that the gear oil when either ?topping up? or replacing should be filled via the drain plug hole and not the vent? Also what would be the disadvantage, if any, of refilling the unit with auto oil?

Many thanks

 

[halmc]

Re: Mercury 50hp lower unit - Water tube?

Hi

Your help with the following would be much appreciated.

I have recently purchased a 1982 4 cylinder Mercury Blue Band, and have removed the lower unit to check the impeller. At the front of the unit there is a ?water tube? that has broken away from the plastic securing nut/gland, this I can repair. However what is the purpose of this tube, it?s sealed at the upper end?

It's the output from your pitot tube wannabe that would feed your pressure operated speedometer if you had one. You can ignore it.

Additionally why does the Clymer manual specify that the gear oil when either ?topping up? or replacing should be filled via the drain plug hole and not the vent? Also what would be the disadvantage, if any, of refilling the unit with auto oil?

Many thanks

'Cause even Clymer knows that if you try to put the oil in from the top, it will have to fight with the air being displaced by the oil. You almost have to squeeze or pump the oil in from the bottom until it comes out the top. Pump if you have a pump, squeeze if like most folks, you buy the 90wt in a tube) You can use auto oil so long as it's 90wt. and say's 'hypoid' somewhere on it. The lower unit on your engine (and with most outboards) is a hypoid gear arrangement.

The principal and I say only difference between the 'automotove' 90wt at Wal*Mart and the "90wt marine gear oil" at your friendly OMC dealer is about $5/tube and the picture of a boat with a pretty girl aboard on the tube.

Ironic that I encounter this thread this AM, 'cause in a few minutes, I'm off to the lake to replace the 30wt. oil that I put in my Merc 45 hp lower unit for testing with auto, Wal*Mart 90 wt. which I plan to squeeze in from the bottom.

If you haven't yet thanked your god for permitting you to remove that lower unit easily, you should.

 

[aarrjimlad]

Re: Mercury 50hp lower unit - Water tube?

Many thanks, yes, I may have said a prayer when the lower unit slipped down with ease: then also thought ''has someone else recently visited this area'', but all is well, the gear linkeage assembly had been incorrectly assembled
Regards
Aarrjimlad