lower unit seals 1958 Evinrude 18hp

[Ron_S]

Recently purchased motor. Do not know history. It appears someone had the lower unit apart because there is blue liquid gasket where the two halves of the gear case join. Changed hypoid oil and ran in tank. Much oil in water. Checked lower unit oil, much water there (light gray). Now it gets strange.
Pulled lower unit, placed pressurizing fitting in one of the lower unit oil holes and pumped using a bicycle pump. First much air bubbled out, mostly around the shift linkage. Some came out the tube part of the exhaust. Some came out a small hole on the gear case. Then the air stopped coming out of the shift linkage seal, and reduced elsewhere. In fact it is so pressurized that I cannot pump more air.
My question:
Did the air pressure cause the linkage seal to seal better and that stopped the leak? To the point that I should not mess with this now? Of course running will give the answer, but I thought someone might know.
Should air be coming out of any place?
What is the purpose of the little hole on the side of the crankcase?

Thanks

 

[HighTrim]

Re: lower unit seals 1958 Evinrude 18hp

Using too much pressure is actually cheating, it aids in the sealing properties. 5 to 7 psi is sufficient to test. Then dunk it, and spin the driveshaft and shift the rod. I would just do a total reseal while you have it down, it needs it.

Do not use that make a gasket junk, clean it all off and use 3M 847 to seal it up.

 

[Ron_S]

Re: lower unit seals 1958 Evinrude 18hp

Thanks. It looks like someone had it apart there and thought they were replacing something. If they did they must not have done it properly. I was hoping to use the motor for the summer and replace the seals in the winter. What is the little hole on the side of the gearcase that lets air bubbles out?

 

[HighTrim]

Re: lower unit seals 1958 Evinrude 18hp

Im guessing you are referring to the drain hole, but post a pic to verify.

 

[Ron_S]

Re: lower unit seals 1958 Evinrude 18hp

Drain hole would be correct. What seal is leaking that causes air to come out of that hole? I know, replace all seals, but I would like to have an idea of the lion I am chasing before I go into the jungle.

 

[HighTrim]

Re: lower unit seals 1958 Evinrude 18hp

Air is coming out of the drain hole with the gearcase removed from the motor and the gearcase vertical underwater when testing?