1960 40 hp Johnson lower unit leak

1960 Rd 22 Been in the family since new. My problem is for the last few seasons when I drained the lower unit I found water in it, no big deal. Last week I ran it for about an hour then loaded it on the trailer and had grease running out of the drain by the top oil plug. I tore it down and found the drive shaft was badly wore at the upper & lower waterpump seals also a cracked pump housing. I replaced the pump, shaft, and both seals. I then ran it in a barrle for maybe 20 min. with the same results oil leaking and water in the gear case. My Father replaced the impeler and seals about 15years ago and I put the seals in the same way, both with the lip down. But I wonder if the bottom seal should be lip up. Anyone know? Or have any ideas where the water is getting in? Sorry for the long post!!<br /><br /> Scott

Re: 1960 40 hp Johnson lower unit leak

The seals should be set so that the springs on them are exposed to the oil, not the water.<br />If you can, it's a good idea to install the seals so they ride on a different part of the propshaft or driveshaft. If that's not possible then you should either find a new driveshaft, have a speedi-sleeve installed, or use a slightly smaller oil seal. If you go the latter route, then make sure you use a corrosion resistant oil seal (ie, stainless), and not much smaller.<br />Right now, you should drain off the oil seal and pressurize the gearcase a bit with air. If you submerge the lower unit like that, you'll be able to see where it's leaking by the air bubbles. You can pressurize through one of the fill/drain screw holes using a carved tire valve stem and a bicycle pump.<br />9 times out of 10, oil coming from one of the drain holes is mistaken for lower unit oil when it's just unburnt fuel and oil coming from the exhaust. If it smells like gasoline or exhaust, that's what it is. But clearly water is getting into it.<br />Did you replace the spagetti, the O-ring on the seal carrier, the o-ring on the shift fork screw, the shift-shaft seal, or the seals on the fill/drain screws? What kind of sealant did you use while assembling it?

Re: 1960 40 hp Johnson lower unit leak

Here's a good tip, the driveshaft oil seal from an old 50HP Chrysler (and likely a Force as they had pretty much the same gearcase) has a double-lip affair and will work in a J/E application. The lips of this seal will ride in different (and hopefully unworn) areas of the driveshaft and may help with the oil sealing problem.<br /><br />Otherwise the other suggestions are great, either find a good used driveshaft or fix the old. A machinist should have no problem welding the bad surface up, turning it back down to original and straightening the shaft. Speedi-sleeves do a good job for around $20 or so each.<br /><br />Also make sure where the shaft rides on the upper bushing/needle bearing, that both the shaft and the bushing/bearing are not worn excessively. The added slop this brings can cause the lots of movement of the driveshaft which can lead to oil leakage.<br /><br />HTH.........ed

Re: 1960 40 hp Johnson lower unit leak

Paul I replaced the driveshaft. I did'nt tear down the gear case so no sealer was used. as far as the shift fork oring its still oe also did'nt think of the shift rod seal. Does anyone have a good diagram of the lower unit on the web? PS. The seals are in right then. <br /><br /> Thanks Scott

Re: 1960 40 hp Johnson lower unit leak

Oh, sure I get it. Somehow I got that 'seals' included the propshaft seal, which would require disassembly of course.<br /><br />Pressurize it and see where the bubbles come out. Hopefully the case isn't cracked too.

Re: 1960 40 hp Johnson lower unit leak

what about your rear seal on the prop shaft? you could be leaking water through that as well.<br />just a thought...

Re: 1960 40 hp Johnson lower unit leak

I will try the air leak test next week and report back. Thanks Scott

Re: 1960 40 hp Johnson lower unit leak

Thanks guys I changed the o-ring on the shift fork pivot and did an air leak check and all seems to be fine now. will be headed to the lake this thursday for the day then we will know for sure.<br /><br /> Thanks Scott

Re: 1960 40 hp Johnson lower unit leak

Good luck, and thanks for keeping us updated!