81 Johnson 25hp

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Bass n flats

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Hello everyone.....This is my first post under this username (previous one was fishinchef but for some reason it won't let me log in anymore). Anyways last month I picked up a 25hp Johnson for my 1752 Lowe from a fellow member hoghunna. Motor starts on first pull and runs great. When I first got it home I check the lower unit lube and noticed it resembled a vanilla milk shake (see pictures below). Being proactive I got a lower unit seal kit as well as a new water pump. The install of both was really straight forward and thanks to Jasper60103 for emailing me a repair manual. Half way through the project I realized I was not taking enough pictures to do a full project how to, but I wanted to post what I did take.

The motor after pulling the cowling
0125B964-8076-4855-820C-6FD3B3220C07-245-0000001606E2868E.jpg


Doesn't this look tasty??
C9533E5D-F1A1-4419-9C0B-1C3789E6893F-245-00000015E74334B1.jpg


Tapping in the new drive shaft seals
59FF76B4-9D99-42E8-8845-3AFD28F53470-245-00000015D6667089.jpg
 
After they are seated
53EE68C7-6FD4-451A-9BE3-438B5287D2B5-245-0000001A2163FD7B.jpg


This was the old impeller, still in decent shape but starting to show signs of rot
51EE74F0-D658-4224-992E-DC4B73F16DF8-245-0000001ADDBF411A.jpg


All ready to go for the new water pump
E82EF78E-FC3A-4BE3-9E1E-56547F2A6C5B-245-0000001B2401FEF4.jpg


again sorry thats all the pictures I took mainly because I didn't want to cover my iphone in grease and gear lube! and my pregnant wife wasn't in the mood to play photographer.
 
Hey, Bass.
Glad to hear it worked out.
For future reference, can you share any tips for
replacing the shift rod seal and other troublesome seals?

jasper
 
Since i didn't take any pictures I will try to explain best off of the factory schematic. Also available here https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1981&hp=25&model=J25RCIM&manufacturer=Johnson&section=Gearcase

If I explain anything incorrectly let me know, definatly not a marine mechanic but it seems pretty straight forward. And I take no responability for these instructions, they worked for me and I hope they work for someone else in the future.

43922.gif


Part # 25 gearcase head assembly. This houses your two prop shaft seals that sit back to back (one seals the oil in, and one the oil out your thicker seal goes on the outside). I took this off the prop shaft and place it in a vise and used an older screwdriver to slowly tap out the seals. These came out relatively easy compared to the drive shaft seals. Once they were out I smeared a little bit of grease in the housing to help the new seals slide in better, and also greased between the seals. I set them in one at a time using a socket and lightly tapped with mallet.

Parts #40 & 41 shift rod busing and shift rod seal. with the water pump, drive shaft, and shift rod removed I turned the lower unit upside down and used a small long socket to tap the busing out. Within the bushing there is a seal. For reinstallation simply flip the LU back over and repeat with a larger socket. Becareful not to hit to hard as you will damage the bushing

Part #39 Drive shaft seals These were a little tricky at first. I had to rig a kind of pry bar to get these seals out (I will add picture later tonight). With the lower unit in a vise I used the pry bar to grab the inside of the seals. Very carefully (not to damage and drive shaft bearings) I placed a long 1/2" socket extension up the bottom of the LU and slowly tapped on the back of the pry bar. I have heard of people using a small puller but I did not have one handy at the time.

Those were the three seals that gave me the most problem and that require "special" tools to remove. The toughest part of the whole project was getting the water tube and shift rod lined back up to reinstall in the exaust housing. It took a small mirror, iphone flashlight, and pregnant wife's assistance to get everything lined up. If someone knows an easier way than that PLEASE LET ME KNOW!
 
Bass,
good write-up. I think you explained it quite well.
Now, if have to do this, I need to find a pregnant wife? :LOL2:
Btw, congrats. =D>

Also, did you have to purchase the seals individually or did you find a kit somewhere?

Thanks again.
jasper
 
Johnson does have a kit but the guy at my local shop just pieced me together the seals. He said it would save me a little bit of money.
 
Bass n flats said:
Johnson does have a kit but the guy at my local shop just pieced me together the seals. He said it would save me a little bit of money.

Ok, I see kits available from sierra and mallory, but not OEM.
Also, what did you do to keep the detent balls from flying out everywhere?
 
Well the first time one of them went flying across the garage but lesson learned and either left it in neutral once removed or help my hand cupped over the clutch dog
 
i put my shift rod grommet on my shift rod and pushed it up and in on my 80 25hp and it worked for me....
 
Well out of curiosity I checked my lower unit lube this weekend after taking the boat out and it is milky white again. So instead of going through the process over again I will take it in before spring and haveit sealed properly. I have no idea which seal it's coming from so I don't want to dismantle it again and waste the time and money. Anyone have any thoughts?
 
Bass n flats said:
Well out of curiosity I checked my lower unit lube this weekend after taking the boat out and it is milky white again. So instead of going through the process over again I will take it in before spring and haveit sealed properly. I have no idea which seal it's coming from so I don't want to dismantle it again and waste the time and money. Anyone have any thoughts?

Sorry to hear. A leak test is the only way to isolate the problem for sure.

I had similar results on a old project motor I was working on. I skipped replacing the shift rod seal which could have been the source of my problem. I lost interest and eventually sold the motor though.

It sounds like you covered all the bases. Did you use 3M 847 sealer? If not, I would coat all the skeg screws. Also, you may want to check the spaghetti seal. The ends must be properly cut or it will leak for sure. Again, use 3M 847 on the mating surfaces.

Keep us posted. Good luck.
 
I used Johnson gasket sealing compound which was recommended by my local dealer. I'm kinda iffy on doing it again, I've got some other boat projects and will probably have the shop do it
 

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