67 Merc 650 Lower Unit Please Help

[JimMachinery]

I purchased this 67 Mercury (s/n 2207052) with my 1967 Naden project boat. I guess I know why the previous owner sold it now.

JB Weld or similar cracked. I just removed the paint to get a look at the area and found this. Oil had no trace of water, but the blue silicone in the lower unit leads me to believe that somebody put fresh gear lube in.

I'm not sure, but I think the metal ring that's split is the bearing carrier thrust washer. I noticed that when I tighten down on the Gear housing cover that it is hard to get the shifter into forward.

Should I try to repair or look for another lower unit?

 

[diaric]

Re: 67 Merc 650 Lower Unit Please Help

you could pressure test the lower unit with no more than 5psi through the fill hole and see if its leaking lube. what are you tighting down on, that makes it shift hard

 

[JimMachinery]

Re: 67 Merc 650 Lower Unit Please Help

Thanks, Diaric.

Tightening down on the nut (called "gear housing cover" in Seloc book). I got suspicious when it backed off easily. I tightened it down again (just hand strength, no torque wrench) and found it difficult to shift into forward.

The washer that's broken is the bearing carrier thrust washer and will almost certainly have to be replaced. The air pressure test is a good idea, I guess I would need a threaded adaptor, valve and gauge to measure pressure drop over time.

 

[diaric]

Re: 67 Merc 650 Lower Unit Please Help

aparently its same thread as a tire valve, some guys have used the rubber end of a blow gun for testing immediate leaks. i've used my lube filler pump with the vent closed, and given it a few gentle pumps and heard the immediate leaks. they seem to leak right away so holding pressure and checking with a valve will probably just assure your mind that it seals good.

 

[Scaaty]

Re: 67 Merc 650 Lower Unit Please Help

Yep on a lot of this...the carrier housing has cracked (maybe a winter freeze...)...it aint leaking, oil not milky, go for it..the shift problem is probably the carier nut shoving every thing tight in the guts..(new T-Washer..(and ya don't need to worry on cranking down, as it only will push on the shaft after that..can't hurt to try...but I think you might be looking a new L/U)