1961 Johnson Seahorse 75hp milky gearlube

[Clippership821]

The manual says water in the gearlube is bad news and that you have to tear the whole lower unit apart and inspect thoroughly to find out what's causing it. What's the most common cause of water in the gear case? Tips? Also, any #'s for seal kit for this?
Thanks

 

[HighTrim]

Re: 1961 Johnson Seahorse 75hp milky gearlube

The number 1 spot for water intrusion into the lower unit is throught the drain and vent screw gaskets. They should be replaced each and every time you service your lu. The other seals follow as the causes of water intrusion such as prop shaft seals, shift shaft seal, drive shaft seal.

Check here as 1 option for the lu seal kit.

"http://www.laingsoutboards.com/newpage4.htm"

 

[rolmops]

Re: 1961 Johnson Seahorse 75hp milky gearlube

Yes it is a good idea to take the lower unit apart,but then again,it does not take a rocket scientist to do this.
Replace whatever seal you can and you may wish to double the seals on the propeller shaft.One for keeping the water out and the other for keeping the oil in.This is done by having the rubber edge of the seal facing the water and the other facing the oil.Why double up do you ask? It is because after 46 years the propeller shaft may have worn a bit on the spot where the seal sits and it may need a little help.
If you use the engine in fresh water only,there probably is not much reason to worry.If on the other hand salt water is involved,you better take care of it right away.

 

[Lakester]

Re: 1961 Johnson Seahorse 75hp milky gearlube

hello,

i attended the 2008 Boat Show in Houston the other day... and that question got asked at one of the engine supplier booths. they said that the rear seal at prop shaft is a major reasong for water in the l/u due to fishing line.

so be sure to check both areas...

regards
lakester

 

[Evinrude Boater]

Re: 1961 Johnson Seahorse 75hp milky gearlube

A pressure test will tell you what's leaking. I found mine was the case had a crack. Stands to reason that if you have water in the oil it might freeze during winter storage and crack the case. Remember, ice sunk the Titanic. If milky oil is left in the gear case over winter the water can settle out of the oil and will accumulate in the bottom of the case. That's where it freezes and causes grief.

 

[Lakester]

Re: 1961 Johnson Seahorse 75hp milky gearlube

A pressure test will tell you what's leaking. I found mine was the case had a crack. Stands to reason that if you have water in the oil it might freeze during winter storage and crack the case. Remember, ice sunk the Titanic. If milky oil is left in the gear case over winter the water can settle out of the oil and will accumulate in the bottom of the case. That's where it freezes and causes grief.

A pressure test will tell you what's leaking

hello,

soon i will drop my l/u. i have it ready to drop short of a few details. all bolts broken free and threads chased and cleaned and reinstalled snuggishly loose. my upper drain plug is a bit buggard from use. 36 yrs of use!! i used an impact screwdriver to POP 'em loose. didnt remove. i will replace top one.

i plan to use the old one as a fitting. drill or mill thru it and set in a valve stem. since its tested at about 14 psi i plan to seal it with JB both sides. then i have a 12v tire pump with a guage... i will let it pump up to 14/15 psi. then let it sit. hope it will hold...

more so, hope it will work. i am optimistic.

regards,
lakester

 

[Evinrude Boater]

Re: 1961 Johnson Seahorse 75hp milky gearlube

I think my manual recommends a maximum of 7-10 psi. I used a small compressor with a cone adaptor for filling an air mattress and just held it tightly in the vent hole. When I got to 10 psi I shut off the compressor and dunked it in a tank. I saw bubbles immediately and the test was over. This was AFTER replacing every seal.

 

[dono16]

Re: 1961 Johnson Seahorse 75hp milky gearlube

Guys, Ive wanted to do this before , but Evinrude boaters meathood doesnt sound very good to me , sorry no ofensse i know u don t need much pressure, but usinga cone and then sealing how did u really keep any pressure in? I;ve been thinking of using a rubber seal groment witha bike pump or using the same with my compressor and just leaving it hooked up , most wont let any back pressure in,,,,,Also i thought u had to leave it in the water or tank for at leat 30 to 40 mins to see whats really goin on??

 

[HighTrim]

Re: 1961 Johnson Seahorse 75hp milky gearlube

To pressure/vacuum test a lower unit:

a) drain the gear oil
b) use an appropriate adapter with a gauge tee'd in to apply pressure or vacuum. I made one out of a lu oil filling kit. No more than 15 psig for pressure. You can use a bicycle pump or any other compressed air source for pressure. For vacuum, you need a vacuum pump.
c) LU should retain some pressure or vacuum for 45 minutes minimum.
d) If pressure doesn't hold, submerge LU in water to find leak source, or simply spray with soapy water [possibilities: drive shaft seal, prop shaft seal(s) (usually two), shift shaft seal and the fill/drain screw washers.]
e) replace offending seal(s) as required.

 

[Evinrude Boater]

Re: 1961 Johnson Seahorse 75hp milky gearlube

Thanks HighTrim for describing the recommended procedure. In my situation I had already replaced all the seals and the leak at the cracked case was obvious when I pressurized it.

 

[WTL]

Re: 1961 Johnson Seahorse 75hp milky gearlube

Check out this article regarding lower units, it seems to be pretty good. I am interested in the idea of using the lubriplate 105 which is heavier and less likely to leak out, but I'm not sure if I'm gonna do that myself. Wonder what the big disadvantages to that are.

http://www.duckworksmagazine.com/06/columns/max/index1.htm

http://www.duckworksmagazine.com/06/columns/max/index1.htm

I swear it was in the message this morning.

 

[HighTrim]

Re: 1961 Johnson Seahorse 75hp milky gearlube

I dont see a link WTL