1961 Johnson Lower Unit Question

[reavesga]

Bought a 1961 40hp Johnson RDS-23. When I pulled the motor arrived I noticed that there was lower unit oil leaking out of the water intake from the motor sitting sideways I assume on the pallet. I pulled the lower unit off and then pulled the water pump housing. Sure enough under the water pump plate there was oil. So, is the problem just the drive shaft seal or should I be looking for a crack in the case. The obvious answer I know is do a pressure test so with that in mind what are the threads in the gear case so that I can attach a nipple to hook up a pressure pump.

When I drained the lower unit oil it was good and black. Not like the last one I did that came out as half water and half oil. On these old outboards, if all the seals are in good shape, does oil leak by that upper drive shaft seal if the lower unit is inverted? I am assuming there are supposed to no leaks anywhere.

 

[kfa4303]

Re: 1961 Johnson Lower Unit Question

Hi reavesga. It sound like the driveshaft seal is bad. You can do a DIY pressure test by using an old foot powered bicycle pump and the threaded nipple portion from the hand pump you use to refill the gear case with oil. You can snip/remove the stock fitting on the bicycle pump and replace it with the threaded portion of the hand pump, held in place with a small pipe clamp. You can get a reseal kit right here at iboats for about $25. If/when the LU sealed properly, you should be able to hold it at any angle without any gear oil coming out.