Filling the lower unit..The lower plug 850 Thunderbolt circa 1977

[washingtonmerc]

I have a hard time believing that I fill the lower unit from the lower plug. Before I take it out I just want to make sure that I don't damage it.

I filled it to where you start to see some fluid coming out of the upper air hole and tried to get the fill plug back in ASAP but if you have done it you know my concern.

Even if some escapes...it is enough...Right

 

[Moody Blue]

Re: Filling the lower unit..The lower plug 850 Thunderbolt circa 1977

If you filled from the DRAIN screw (bottom screw) until oil came out of the VENT screw (top screw) then you did the job properly. The motor should be in a vertical orientation when filling.

You should install the vent screw before removing the fill bottle. That will reduce the amount of leakage from the drain screw when you remove the fill bottle.

 

[rosser1]

Re: Filling the lower unit..The lower plug 850 Thunderbolt circa 1977

yeah you must buy and use the oil for boat foot, it comes with a screw in tube that screws in to bottom hole and you pump it til oil comes out top vent hole, then screw top vent plug back in. try using new gasket ring seals, better to be sure that they are new and won't let water in, than to reuse old seals and water does get in foot. then unscrew oil filler tube and screw in bottom plug, what little bit of oil comes out won't hurt or be alot.

 

[BoobieBouncer]

Re: Filling the lower unit..The lower plug 850 Thunderbolt circa 1977

The manual for my 850 says to drain 1 ounce of oil out after filling to account for expansion.

 

[JDusza]

Re: Filling the lower unit..The lower plug 850 Thunderbolt circa 1977

Putting the top plug in first will act like putting your finger over the top of a straw. Not much oil should come out of the bottom with the top plug in first.