64 Evinrude 18 HP Leaking Gear Oil...somewhere

[j5wentworth]

I inherited my grandpa's 1964 Evinrude Fastwin 18 HP. When I first tried running it, it leaked lower unit oil out everywhere. So, I replaced every seal and bushing possible and resealed it. Also replaced the impeller. Got it sealed back up and fired it up. Within a few minutes, I saw oil pooling in my garbage can. When I looked, I saw gear oil leaking out of the seam where the lower unit bolts up to the mid-section. Dropped the lower unit and saw milky gear oil all over the impeller housing and driveshaft area. I replaced that drive shaft seal and it was nice and snug when I installed it. I made sure the top of that seal had the metal face facing up and made it flush with the housing. Shift rod O-ring was placed in and the tapered end of the bushing was face down. Didn't see any cracks in the housing. It's not leaking anywhere around the lower unit housing cover or bushing where the prop is connected. Both fill and vent plugs have the plastic seal.

So, where should I start looking? I'm about to do the most painful thing and take it to a shop...

 

[oldboat1]

Doesn't look like gear oil, offhand. Does it have a sulphur smell? May be looking at debris from exhaust, mixed with water.

 

[j5wentworth]

Doesn't look like gear oil, offhand. Does it have a sulphur smell? May be looking at debris from exhaust, mixed with water.

Definitely gear oil. I drained the oil and it was all milky after only 15-20 mins of operation.

 

[oldboat1]

Have it pressure and vacuum tested. Can do that yourself with a small pump, l.u. removed and immersed in a tub (look for bubbles to identify leaks). A mityvac works well for vacuum testing.

 

[j5wentworth]

I did a redneck pressure test by putting gear oil over the drive shaft seal and shift rod bushing and then pumping in new gear oil. I saw bubbling around the perimeter of the drive shaft seal. With that said, all of the videos I watched and online research, no one used any sealant around the outside of the seal before installing it. Therefore, I did not. Short of removing and installing a new one coated in sealant, could I clean and seal around the top of the seal and the housing? Ugh, this thing...

 

[oldboat1]

don't think that will work. Probably need another seal. Trying to remember whether I used any sealant on the last one I did -- likely used a little Permatex.

 

[j5wentworth]

Do I need sealant around the shift rod bushing too because I never put any on there either?

 

[lindy46]

Do I need sealant around the shift rod bushing too because I never put any on there either?

A little sealant wouldn't hurt.

 

[bspeth]

I use spray tack on most seals or you could use perfect seal I guess.