72 johnson 20hp broke on me need help please....

[Root Rat]

So I recently fixed the electrical problem on my 20 hp. It runs pretty damn good now and starts really well. I went to the lake today to test her out and all went well till I opened her up. It had a little hesitation to get moving but I got to speed and off i went. The motor seemed to skip and the wot revved the motor really high. The transmission popped out of gear? I throttled down to shift it back into forward and the shift lever wouldn't move, it was stuck in the forward position...? I turn the engine off and tried to see what might have happened? I was able to get it into neutral again and started the motor right up first pull. As i shifted the motor into forward I started going backwards? The shift lever is stuck in the forward position right now. If I gave it any gas I went backwards not forward? I am not sure what needs to be fixed or where to start? I was looking for vids to watch so I can see what needs to be done. Also to find out what I might need to order to get this next part of the repair started...? I have looked at the diagrams from marineengine.com so I can see the parts. My main issue is I have never tackled something like this before. I am clueless as to where I should start, or what actually needs to be replaced... ANY AND ALL HELP WILL BE GREATLY APPRECIATED.

Thanks,
Capt Root Rat

Motor 20R72R
Johnson 20hp

 

[Crazyboat]

I'm no wrench turner, so you know. I'd start with connections, sounds to me like something broke in there. Doesn't sound like it's a too expensive fix, if you can't see what broke, I'd try a shop and see if they can make the repair. You Tube is always the first place to look. (Even though I thought of it last)

 

[Pappy]

By chance did you replace an impeller along the way?
If so it sounds like you did not get the brass shift rod connector properly re-attached to both the upper and lower shift rods.

 

[Root Rat]

By chance did you replace an impeller along the way?
If so it sounds like you did not get the brass shift rod connector properly re-attached to both the upper and lower shift rods.

I didn't change anything there. I only messed with the magneto, plugs and wires....

I'll need to look at the brass shift rod? I plan on starting to disassemble the gear case today. But I wouldn't know what to look for when I get inside?

 

[MrGiggles]

I didn't change anything there. I only messed with the magneto, plugs and wires....

I'll need to look at the brass shift rod? I plan on starting to disassemble the gear case today. But I wouldn't know what to look for when I get inside?

You'll need to disconnect it in the process of removing the lower unit, it'll be behind a small plate in the leg with two screws.

Those gearcases are very simple and straightforward to disassemble. An oil sample will tell you something, if there is metal in the oil then you have an internal problem.

 

[Root Rat]

You'll need to disconnect it in the process of removing the lower unit, it'll be behind a small plate in the leg with two screws.

Those gearcases are very simple and straightforward to disassemble. An oil sample will tell you something, if there is metal in the oil then you have an internal problem.

So when I removed the cover to access the shift link, it was definitely not attached. The lower shift rod was free of the bracket that attaches them together. So a quick alignment and tightening and its back together. THANKS FOR THE INFO!!! Gotta run to the lake again to test it. Fingers crossed thats all it was.

 

[Lost But Happy]

With a lot of things, it's usually the low-hanging fruit that is the culprit. Good Luck and report back!

 

[Root Rat]

By chance did you replace an impeller along the way?
If so it sounds like you did not get the brass shift rod connector properly re-attached to both the upper and lower shift rods.

Ok so I don't think i got the linkage set right. It didn't want to go into forward and stay there. I may have had it to compressed/short to engage forward properly. I felt it rattling my hand on the lever at first so I want sure if it was stripped or miss aligned. I decided to stop the motor and head home. So I checked the gear oil, and there was another issue. It was milky, so the seals aren't any good. I have a new set on order and await those. In the mean time I looked at my gears inside the gearcase. So far they all look pretty good, but I did see my lower shift rod had a ton of surface rust on it. I dont know if this is normal or not? It looks to be in an area that gets wet but I could be wrong? I'll be taking the gearcase to work to de-grease it and cleaning all up best I can. From there I'll inspect it to see if I have any other issues? (If I even know what to look for... lol)

 

[MrGiggles]

Ok so I don't think i got the linkage set right. It didn't want to go into forward and stay there. I may have had it to compressed/short to engage forward properly. I felt it rattling my hand on the lever at first so I want sure if it was stripped or miss aligned. I decided to stop the motor and head home. So I checked the gear oil, and there was another issue. It was milky, so the seals aren't any good. I have a new set on order and await those. In the mean time I looked at my gears inside the gearcase. So far they all look pretty good, but I did see my lower shift rod had a ton of surface rust on it. I dont know if this is normal or not? It looks to be in an area that gets wet but I could be wrong? I'll be taking the gearcase to work to de-grease it and cleaning all up best I can. From there I'll inspect it to see if I have any other issues? (If I even know what to look for... lol)

Thank Pappy, he was onto it first. Make sure you replace the O-ring on the shift shaft, it may very well be the culprit and is often overlooked. People usually go for the prop seals first.

When you have the lower unit apart, ensure that the detent balls and spring underneath the shift dog are present and in good condition, and that the teeth on the shift dog and drive gears are still in good shape.

 

[Root Rat]

By chance did you replace an impeller along the way?
If so it sounds like you did not get the brass shift rod connector properly re-attached to both the upper and lower shift rods.

So on the propeller shaft i have, it doesn't have the hole in it for the ball dents and the spring? Also my shift dog doesn't have any indentations to accept the ball detents. I assume this is why my motor pops out of gear when I am moving. Does my motor require the dents on the propeller shaft? I can find a shaft with the holes, but the shift dog is had to find or way to expensive.

 

[Pappy]

There were tons of gearcases out there in the vintage days that did not have the detent groove, balls, and spring. They will stay in gear if everything is adjusted properly and the drive faces of the clutchdog and gear lugs are in good condition and not rounded off.
After going through this scenario several times I am surprised that noone has mentioned the fact that you have a shift adjustment up at the gear shift lever! You can loosen it and adjust to pull farther into either forward or reverse gear.
If you do have the gearcase apart I would love to see some close up photos of the drive lugs on the clutch dog and forward gear.
Also. are you sure it is jumping out of gear and not a prop hub slipping? You can hold your hand on the shift lever and it will jump in your hand if the gearcase is jumping out of gear but remain relatively stationary if the prop hub is slipping.

 

[Root Rat]

There were tons of gearcases out there in the vintage days that did not have the detent groove, balls, and spring. They will stay in gear if everything is adjusted properly and the drive faces of the clutchdog and gear lugs are in good condition and not rounded off.
After going through this scenario several times I am surprised that noone has mentioned the fact that you have a shift adjustment up at the gear shift lever! You can loosen it and adjust to pull farther into either forward or reverse gear.
If you do have the gearcase apart I would love to see some close up photos of the drive lugs on the clutch dog and forward gear.
Also. are you sure it is jumping out of gear and not a prop hub slipping? You can hold your hand on the shift lever and it will jump in your hand if the gearcase is jumping out of gear but remain relatively stationary if the prop hub is slipping.

Well I have no idea where I would find a shift adjustment? I will have to look for it in the diagrams to have a chance at finding it.

I think it jumped out of gear because it was very jumpy when I first tried to hold it in place.

As for the forward gear? I cant tell the difference between the 2...sorry.. lol but here are a couple of pics... I had put a little white lithium grease on them because they are sitting in my garage in open space. I didn't want them to start getting any rust.

 

[Pappy]

Well I have no idea where I would find a shift adjustment? I will have to look for it in the diagrams to have a chance at finding it.

I think it jumped out of gear because it was very jumpy when I first tried to hold it in place.

As for the forward gear? I cant tell the difference between the 2...sorry.. lol but here are a couple of pics... I had put a little white lithium grease on them because they are sitting in my garage in open space. I didn't want them to start getting any rust.

On the second and third photos I can definitely see wear on the drive lug faces.
Secondly you have no clue where to look because you have not looked ....... yet!
Very simple. At the base of the shift lever you hold in your hand to shift the engine you will find the adjustment close to the 9 oclock position where it mounts to the midsection. there should be a clamp screw to clamp the shift handle to the shaft and there should be a hex head bolt with a 7/16" head on it that you can loosen, adjust as necessary, and re tighten.

 

[Root Rat]

On the second and third photos I can definitely see wear on the drive lug faces.
Secondly you have no clue where to look because you have not looked ....... yet!
Very simple. At the base of the shift lever you hold in your hand to shift the engine you will find the adjustment close to the 9 oclock position where it mounts to the midsection. there should be a clamp screw to clamp the shift handle to the shaft and there should be a hex head bolt with a 7/16" head on it that you can loosen, adjust as necessary, and re tighten.

Thanks for the info Pappy I appreciate the help...!!! I looked on my shifter and I have a pinch clamp type adjustment I found. That might be what you're talking about on my motor. I will attach a pic...

Ok, so with that bit of wear that you see. I don't know if that was there or if I did it when my shift linkage separated that day. I did try to put it back in gear a couple of times and felt it "grinding" a bit as I tried. I am guessing that is something I caused from trying to get it back in gear. Is the wear bad? And should I be looking for new parts to replace them while I still have the whole gearcase unassembled...?

 

[Pappy]

You can either look for a forward gear/clutch dog with no wear or look for a complete used gearcase which may also be a gamble. If replacing just the parts you must replace as a pair.
The wear is easily enough to allow it to jump out of gear. When it is back together let me know and I can tell you how to insure you are all the way into forward gear.

 

[Root Rat]

You can either look for a forward gear/clutch dog with no wear or look for a complete used . may also be a gamble. If replacing just the parts you must replace as a pair.
The wear is easily enough to allow it to jump out of gear. When it is back together let me know and I can tell you how to insure you are all the way into forward gear.

Hey Pappy, so as far as teaching me how to know the drives are in gear it might be a bit. I have decided that since the Jack wagon that sold me this motor in such yucky shape, i need to take it all apart. I have the motor off and the exhaust housing almost apart now. This thing is DIRTY and needs cleaned. On top of that the baffle gasket is junk!!! Looks like he used RTV silicone between them. It's coming off in chunks and there is debris all over. I'll be up to my elbows just trying to clean this thing... and lord only knows what else I will find? Or miss as all I know to look for is if all the parts are here according to the diagrams. I have the gear case all cleaned up and painted with 4 coats of Clear coat. Painted it white and have the gasket rebuild kit ready. I might put it back together this weekend. Still debating that, and or if I should buy a set of lowers. Found some on Ebay for around $200. Some many things to look at and do...

 

[Root Rat]

My inner exhaust tube looks GREAT!!! And the was no gasket in the housing either. Man when I buy a fixer upper it's NO JOKE!!!

 

[RaisedByWolves]

My inner exhaust tube looks GREAT!!! And the was no gasket in the housing either. Man when I buy a fixer upper it's NO JOKE!!!

What the hell……

 

[Pappy]

On that design gearcase you definitely have to replace the shift shaft Oring while in there.
What did you decide to do on gears?

 

[Root Rat]

On that design gearcase you definitely have to replace the shift shaft Oring while in there.
What did you decide to do on gears?

So I got the lower unit seal kit by Sierra to replace all the seals/o-rings. If the shaft Oring is in the kit, I will be replacing it. If it is not let me know what part# it is and I will get one. Here is a link to the diagram for my motor...

https://www.marineengine.com/parts/...=20R72R&manufacturer=Johnson&section=GEARCASE
Thanks

As far as the gears go, I can't afford to buy them right now. I'll need to reassemble the gear case with what I have and hopefully get it to work without any major issues....