Logo
FULL SITE MENU

Need help bringing a Johnson 20R273A back to life

Thanks Timguy. That's how I wired my kill switch I guess o just need to check my connections. I did check the switch for continuity and it seems to be working correctly.

If it could just be a shift shaft leak then maybe I'll try to check that before I tear the whole thing apart. During my online research I've seen folks make a do-it-yourself lower unit pressure tester kit of a bicycle pump and the fittings from a lower unit oil flush kit. While I don't mind recording the whole thing I also wouldn't mind an easier, quicker fix in the name of getting this rig on the water sooner. It's getting warm here in Georgia.

I am getting excited about finally getting out there and running this old motor. It'll give me peace of mind to know that I've gone through the whole thing to minimize the chance of any surprises once I have my wife and son aboard. And the fact that I'll be familiar enough with the motor to fix most things that might come up out there. In my mind that's a prime advantage of buying an old motor like this one and rebuilding it versus buying a shiny new one. I also like the fact that you can disassemble/ reassemble much of the old Johnson with just a flat head screwdriver. I've already put together a list of the tools kit items I'll bring with me on the boat and it's less than the tools in my motorcycle tool kit.
 
That is why I embrace the technology of the 50's, 60's and 70's. By knowing your motors, applying simple maintenance and proper operating techniques.....you can count on these with your life. Electronics can fail as proven recently with the airline disasters. A dead boat really won't hurt you, but it can sure create life threatening problems in some remote areas and brutal conditions I find myself in up in the Canadian wilderness. Never use ethanol fuel for one, and always run all fuel out of the motor when it will be stored for over a month. Keep your water pump impeller fresh....usually every 10 years, more often on newer stuff. Why? Impellers are wrapped in there more tightly with thinner fingers which are forced to flex mote as they rotate. Rubber compositions also tend to be less quality than what was provided us years back.
Keep up the good work, I applaud your thinking and procedures.
 
Timguy-
Looks like you were right about the shift shaft seal. Spent a couple of hours in the shop today. Removed the lower unit and impeller housing which didn't go as smoothly as I'd hoped. 2 of the 4 bolts on the underside of the anticavitation plate snapped the I was removing them. Luckily i was able to get the bolt shafts out with vice grip pliers and a propane torch. And 2 of the 3 impeller housing screws snapped. 1 of these came out with the torch and pliers but the other had to be drilled out and tapped. Didn't do a perfect job of it. It's a bit crooked but I think it'll hold the screw.

Rigged up a pressure tester using the fitting from a lower unit finish kit, a Schrader valve from agm old bike tire, a couple hose clamps and a bicycle pump. Pumped it up to 10 psi and started spraying the seals with soapy water. The drive shaft seal and propeller shaft seal both look fine with no bubbles. Driven shaft bearing looks intact. The shift shaft seal bubbled immediately.

I watched a video on YouTube showing a guy rebuilding an entire Johnson 25 hp lower unit. Very detailed. He drives the shift bushing out gettin thr bottom using a special punch in order to replace the O-ring underneath. Looks like I'm gonna order the special punch, O-ring and replace that seal.

My question is... should I replace the drive shaft seal and prop shaft seal while I have it apart, or should I not fix things that aren't broken?
 
I would do all the seals and be sure to use stainless bolts. You can order everything from Tim's Outboard at 218 682 2331....even used bolts. Be sure that you don't drive the shift shaft seal retainer bushing in too tight. It can squish and squeeze too hard onto the shift shaft. Use grease when installing it. If you drive the bushing/retainer in too tightly, the hole for the rod will be too small and possibly be damaged when you push in the shift shaft. Make sure there are no burrs on the shift shaft, clean up the end with fine sandpaper.
 
No relation, just so happens I have dealt with so very many parts/used outboard businesses, but really hit it off with these guys, they are so professional, polite, informed, and reasonable. Minnesota has lots and lots of clean outboard parts with no salt and a 6 month a year season.
 
Well I had already ordered the parts I needed, but if it was your sp I was going to cancel the order and buy from you. Can't tell you how much I appreciate all your advice and everyone else who's responded. This project would be nearly impossible without all the help.
 
You have been a very good customer, it is a pleasure to try to help someone of your caliber, we donate our time to help good people.
 
Finally got all my parts in to rebuild/reseal the gear case.

Question- I have removed the drive shaft assembly. Im attempting to remove the gear case head assembly in order to replace the seal inside it. Should it slide easily off the end of the prop shaft that the propeller attaches to? Is there a trick to removing it? Mine does not seem to want to slide off that end easily. There is a burr in the prop shaft at the opening of a hole that is drilled perpendicular through the shaft which I think may be causing the head assembly to bind instead of sliding off smoothly. Just want to confirm that there's not a trick im missing before I file off that burr.
 
Thanks Fdrgator. I think that the burr that is making mine bind was caused when the drive pin snapped in the past. Once I got my new drive pin in the mail I realized that the one that came with my motor was not stock. Way smaller diameter than stock. Wouldn't have taken much to break that little pin. I'll file off the burr and continue with reassembly on Thursday. With any luck I can get the gearcase back together, slap the motor on the back of my boat and take her for a maiden voyage by the end of this weekend!
 
I for one will be glad to hear a favorable report. The shear pin holes are often messed up. Just take your time and get it leveled off. Gator is not a man of many words but sure knows this business. This is a very rare post in that it has broken 100 threads.
 
Last edited:
Timguy- I just noticed yesterday that this thread was at 100 posts and started 6 weeks ago! Can't say enough how much I appreciate everyone's help. This site and the expertise found here are a huge so valuable to people like me who le to turn wrenches underneath the shade tree. I'll say it's been a bigger project than I was expecting but when I finally get this thing on the water it's gonna be an exciting moment indeed!
 
As sometimes happens in my business I got the day off work unexpectedly today. Got the gearcase seals removed and replaced without any major difficulty. When I finished I hooked up the pressure tester and did have a small leak around the shift shaft bushing. Per Timguy's advice I was careful not to drive the bushing down too hard and I think I failed to seat it all the way into the washer below it. A couple of taps with a punch and it sealed tight. Held 15 PSI for 10 minutes without losing pressure. Everything seems to spin and shift as it should.

Got the lower unit reinstalled and set up my test tank and couldn't get it to start.I have weak spark again. While I was waiting for the gearcase parts I replaced the spark plug wires that were routed incorrectly. Looks like I'm back to troubleshooting the ignition.

Ignition question... I don't have the special ring to help position the coils on the bosses on the armature plate. I've been doing it with a straight edge. Could that be my problem? Are my coils too far from the magnets? I have enough time and money invested at this point I'm beginning to wonder if I should order the ring. All of the ignition parts are new. Can't think of anything else it could be.
 
Mike. They don't have to be that precise. Joe Reeves has the correct coil adjusting proceedure ready to display for you. Did you put in new points? Did you put in the new exciter or low energy coil that you are referencing for adjustment?
 
Timguy- Although my motor is a 1973 it doesn't have the ignition configuration shown in the 1973 parts diagram with an exciter coil and an ignition coil/ laminate. Instead mine looks like the 1972 diagram with 2 coil/ laminates, 2 condensers and 2 breaker points. I replaced all of those parts and the plug wires and plugs with new parts.

I took the coils off in order to replace the plug wires to route them correctly. The only other thing I did differently than the first time i that i set the timing using the timing fixture instead of just gapping the points to .020 at TDC. I ordered the timing fixture tool before I realized the was about way to do it so I thought I might as well use it.

I guess I'll pull the flywheel this weekend and check for loose connections. Maybe clean the points with alcohol even though they're new and should be clean. And I'll disconnect the kill switch although I would think that would completely eliminate spark if it were shorted.
 
Mike from Atlanta said:
I'll pull the carb and double check it when I get a chance. Unfortunately domestic duties call for the rest of today. My wife is remarkably unconcerned about whether or not my outboard is running smoothly :) It'll be Wednesday before I can work on it again.
Click to expand...

Before you pull the carburetor again be sure and check the packing on the low speed needle.
 
Yes I forgot you had the 1972 system. Check all you were going to and set the coils back so the very top of those little chamfered posts is even with the face of the coil laminated core. If your using a straight edge up from the face of the posts, you may very well be too close to your flywheel magnets. Is there any sign of them rubbing?
 
Mike... The timing fixture for setting the points is nice to have but in a pinch... simply having the fiber rubbing portion of the points aligned with the flywheel key, then sitting the points so that a .020 gauge will slide through BUT a .022 will not will have the points set within factory specifications.

Installing coils upon the armature plate "without" the special installation ring tool.... Look closely at the aluminum towers that the metal portion of the coils sit upon... notice that small bevel there... the metal portion of the coils should align with the inside bevel to obtain the proper distance from the flywheel magnets.
 
Timguy and Joereeves- I aligned the face of the coils with the inside of the beveled posts. I think im doing it correctly in the manner you're both describing. When I lay a metal square across the top of the armature plate as a straight edge the face of the coil sits about 1/16" inside of it not touching. I haven't previously seen any signs of rubbing on the coils but I'll check again hopefully today when I pull the flywheel.

Joereeves I'm going to double check my timing adjustment with feeler gauges just to make sure im not doing something grossly incorrect with the timing fixture. Im also going to vo get an analog multimeter. I used my digital meter since that's what I had but at this point I want to do everything I can to get this thing running correctly.

Flywheel75- When you say low speed packing do you mean the plastic bushing that the needle passes through on the outside of the carb? I replaced that with a new one when I rebuilt the carb.
 
Digital meters...... For some reason, I keep obtaining what appears to me false readings, and I back up to using an analog (needle type) meter.

EDIT: In looking through my previous post #110... one portion sounds contradictory... the part that states: setting the points so that a .020 gauge will slide through "BUT a .022 will not will have the points set within factory specifications".

Probably should have a hesitation indication after that "not" to read: "setting the points so that a .020 gauge will slide through BUT a .022 will not... will have the points set within factory specifications".

Yeah, that's better... a little hesitation straightens it out okay. :)
 
Last edited:
Joereeves I had an old Sears brand analog meter that I inherited from my grandfather. I pulled it out of the box to use for this project and unfortunately the battery inside had leaked and the acid destroyed some of the meter internals. I'll pick up a new one. Seems fitting to use an analog meter on this old outboard.
 
I was raised using analog meters. One obvious advantage of having an analog is testing anything involving a rheostat such as fuel level transducers, volume and gain controls, light dimmers, etc.... you look for smooth operation of the needle without glitches. These tests are virtually IMPOSSIBLE with digital. Sorry if I'm old school, but I am also practical.
 
Last edited:
Got it running again today! Pulled the flywheel and checked the point gaps at TDC. One was way bigger than. 020 and the other was way smaller. The directions that come with the timing fixture say that the analog meters respond quicker and are therefore better for this process. Went and picked up an analog meter and repeated the process. Then double checked the points gap just to be sure I wasn't way out of the ballpark. This time got .020 and .014. Looks like this old motor really doesn't like digital technology.

Put the flywheel and pull start back on got much stronger spark. Set my test tank up and got her started in only a handful of pulls. Seemed to run fine but was not putting out any water at the telltale so I killed it after about 10 seconds. The water level in the tank was at least as high as the water pump so that's not the problem.

Tomorrow I'll start trouble shooting the water pump. I've seen videos where people used a cordless drill to spin the drive shaft while the lower unit sits in a bucket. That would allow me to narrow down if the problem is with the water pump or a blocked passageway. I suspect the pump because it was working ok before I replaced it.
 
Yes, you will likely find the problem in the impeller area. Remember clockwise rotation from above, so impeller fingers bend counterclockwise from above.
 
Thanks Timguy. I think I had it oriented that way but will double check tomorrow. I definitely put the tiny pin in the drive shaft that engages the impeller. I also paid attention to getting the water tube lined up with the impeller housing when I reinstalled the lower unit although it's kinda hard to tell when you're sliding it on. I have a feeling that it's something simple and will be apparent once I dig into it tomorrow. Im cautiously optimistic that I'll have it running, idling, shifting and pumping water tomorrow. My boy just turned 6 months old on the 17th so I may be able to get him out on the water at six months just like yours.
 
You have persevered and this should be a good motor. A dental mirror should be in your tool arsenal for these pump tubes. I ruined a 25 Merc a few years ago because I was careless and the pontoon boat was not at a place where I could test it.....the owner never checked the pee hole as I had asked, he ran it until it seized up. I had to rebuild it for free. Yes, I'm an idiot, just like my wife says.
 
Dental mirror... sounds like a cheap a perfect solution to that problem I'll go pick one up tomorrow.

In regards to your customer who ran his motor without checking the pee hole...I can't imagine ever doing that under any circumstances. Fresh from the mechanic or not. It's the whole reason that outboards have a telltale. I guess common sense is not so common.
 
timguy said:
the owner never checked the pee hole as I had asked, he ran it until it seized up. I had to rebuild it for free. Yes, I'm an idiot, just like my wife says.
Click to expand...

I have to disagree with that statement Tim... you're not the idiot, your customer is. Rebuilding it for free keeps your reputation intact, plus it shows character. Customers of that nature... after settling and resolving a conflict to the customers satisfaction... speaking for myself, he would be subject to taking his engine(s) elsewhere.
 
Back
Top