1966 Johnson 100HP water in lower unit

[colsoncj]

I keep getting water in my lower unit, and I have no idea how its getting down there.... I've got new seals below the water impeller, and new gaskets around the lower unit... I know my prop seal leaks a little, but I don't think thats the entire problem... Also, once it does fill up with water, the lower unit grease drains out of the rear of the lower unit, between the two halves... I'm pretty sure my lower unit grease shouldn't even be able to get up that far (same area as the water impeller). Does anyone have any ideas?

 

[OBJ]

Re: 1966 Johnson 100HP water in lower unit

Here's a suggestion col....drop the lower unit and drain it. Rig a bicycle pump to either the drain or vent plug hole. Put 10 to 15psi air press in it and dump the lower unit into a garbage can full of water. Should tell you where the leaks are real quick.<br /><br />Should not run even with a seal that "leaks a little". Water is a great hydraulic fluid and can push the gear lube right out of the lower unit. Find the problem areas and address them.<br /><br />Keep us posted on what you find.

 

[colsoncj]

Re: 1966 Johnson 100HP water in lower unit

Thanks for the help... I'm doing a complete tear down now... Can you use silicone to make the gaskets for inbetween the lower unit halves and between the lower unit and the exhaust housing, or is it picky enough to require an actual gasket?

 

[Mod2]

Re: 1966 Johnson 100HP water in lower unit

Col....DO NOT use silicon as a gasket. It just don't work. The oil (gear lube) will make it mush in no time.

 

[colsoncj]

Re: 1966 Johnson 100HP water in lower unit

Thanks for the advice on that one... Ive used silicon for gaskets in several automotive applications, ranging from differentials to waterpumps, and have never had an issue in all my years... I just didn't know if there was some additive in marine gear lube that didn't agree with silicon

 

[colsoncj]

Re: 1966 Johnson 100HP water in lower unit

Well, I did my own version of testing... <br /><br />With the lower unit drained, I dropped it in, only covering the prop seals. Let it sit for 10 minutes and pulled it out. Dropped the plug, and out comes a little water. Conclusion: time to change prop seals.<br /><br />I then removed the whole lower unit, water impeller housing, impeller, and wear plate. I then tilted the unit and filled the upper area full of water, submerging the driveshaft seals below the impeller. While doing this I had the lower drain plug removed and watched for water. 10 minutes passed, and no water. Conclusion: Upper seals are good. This check also partially tested the seal between the two housing halves. <br /><br />I'm currently in the process of changing the prop seals, and should know the verdict soon. <br /><br />FYI if you change the prop seals, change the prop bearing in the outer plate... trust me, you'll bust it getting it out, so may as well go ahead and buy one, so you don't have to track one down the next day (like I am).

 

[REELSPORT]

Re: 1966 Johnson 100HP water in lower unit

I have a 69 rude 55 hp and i replaced the seals below the water pump and ran it on the muffs and it still had water in the lower unit. I thought it could get any water behind the prop running on muffs but I was wrong I replaced the seals behind the prop and now there is no water in lower unit at all