Lower unit Questions

[Weiss Man]

1979 Mercury 200 (20hp) thunderbolt.

Ok,

The engine is now running great. Thought I would drain and refill the lower unit and the oil came out looking like chocolate milk. So, I know that there is a leak somewhere.

First Question is; on the lower unit there is a vent screw and in front of it there is a plug that has the word flush embossed in the housing, What is the function of the flush plug?
Second question; If I squirt oil into the flush plug, the oil leaks out of the water intake below. Does that sound any alarms? When I refilled the lower unit (from the bottom plug) it did not leak.

Thanks,

Weissman

 

[FLATHEAD MAC]

Re: Lower unit Questions

milky oil probably from bad waterpump seal/o-ring change whole wp kit with impellar.

the flush plug is what it is "flush" , to hook up water hose and flush out cooling system thats why oil is leaking out of waterintake when squirted with oil

 

[Weiss Man]

Re: Lower unit Questions

Thank you, I was worried that the flush plug was for flushing the gear case.
You did not mention the prop shaft seal, is that something to be less concerned about?

Thanks again

 

[FLATHEAD MAC]

Re: Lower unit Questions

IF prop shaft seal was leaking you would prob be low on fluid from loss due to the leak