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Seized 1972 Johnson 4 hp - Can it be saved?

S

sobro

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Howdy

I recently acquired a 1972 Johnson 4 hp (model 4R72S). I wasn't able to test it when I bought it, but I replaced the fuel pump as well as the impeller. I also drained the gear oil out of the bottom end and replaced with new. After that, I placed it on a sawhorse, filled up a garbage can and let her rip!

It didn't start right away...I had to pull several times before I could hear it sputter. Then, it took off! Unfortunately, I could only run it at about 3/4 throttle (and above) since it would die if I backed off too much. After I ran it for a short time, it would randomly die and I wasn't able to start it for a while. Then, after a few minutes (perhaps it needed to cool down?) I was able to repeat the process with the same results. It would run for a short time (and sound great!) then just stop. No sputtering - just stop.

Well, a smarter man might have stopped what he was doing and tried to figure things out, but since one wasn't present, I repeated this process a few times. Unfortunately, the final time that I ran it, I found that after it quit, something was seized and I couldn't turn the flywheel. I let it sit for about two hours and when I returned, it was still seized.

Some facts:

1. There was a very strong mist coming out of the lower leg of the outboard, so it seemed that it was pumping water

2. I touched the powerhead after it seized and there was some water on the tip of my finger. It sizzled.

3. I also noticed that there was a hole in the expansion plug found on the carburetor. Very small, but noticeable none the less

4. I have not taken anything apart yet since the outboard it up at the lake right now...and I'm not :(

Anyway, if I can save this outboard, I would like to do so. It was in fairly decent shape when I purchased it and I feel that a tough old outboard shouldn't have to suffer because of my boneheadedness!

If anyone has some suggestions on where to start, I am interested to hear your thoughts. Hopefully I can save this little guy...
 
Well I would think it wasn't pumping water properly and your bearings got hot, expanded and the engine stopped. Cooled a little (happens quick when the bottom end is in cold water), and you repeated the process. Now it's bound up. If it's a mechanical issue, which it sounds like it is it isn't cheap to fix. BUT, I would first pull the water pump and look at the impeller, that will tell you alot.
 
joeycamaro said:
Well I would think it wasn't pumping water properly and your bearings got hot, expanded and the engine stopped. Cooled a little (happens quick when the bottom end is in cold water), and you repeated the process. Now it's bound up. If it's a mechanical issue, which it sounds like it is it isn't cheap to fix. BUT, I would first pull the water pump and look at the impeller, that will tell you alot.
Click to expand...

Ok - thanks. Two questions: 1. Even though I saw water coming out of the back of it, could it still be pumping incorrectly? If so, then why? 2. Also, since I replaced the impeller (perhaps not as I should have) would it really look that much different, or is there some specific thing that I should be looking for?
 
When you replaced the impeller, did you grease the housing? Also its possible your cooling line(s) are plugged inhibiting water flow to certain areas. It will appear to be pumping. Other than that, possible wrong mix ratio of gas and oil, rookie mistake but it happens. How long did the engine sit before it ran, could be alot of corrosion buildup. That's just some ideas I would throw around. I have learned though, go for the easiest fix first and in my opinion it got hot, and if it's getting hot you probably have a water pump issue
 
joeycamaro said:
When you replaced the impeller, did you grease the housing? Also its possible your cooling line(s) are plugged inhibiting water flow to certain areas. It will appear to be pumping. Other than that, possible wrong mix ratio of gas and oil, rookie mistake but it happens. How long did the engine sit before it ran, could be alot of corrosion buildup. That's just some ideas I would throw around. I have learned though, go for the easiest fix first and in my opinion it got hot, and if it's getting hot you probably have a water pump issue
Click to expand...

Unfortunately I did not grease the housing - once I get a chance I'll pull it back apart and have a look at it again (water pump first!). Not quite sure how long it sat since I got it out of an antique shop...but since it was only $35, I couldn't really pass it up! I'm fairly certain that the mix was ok since I was using it on my other boat. The only difference was that I added a little Seafoam to it before I started it up - but that's it.

Thanks again for all of your help!
 
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