Resto/Rebuild 1973 Johnson 40hp!

[78 mckee]

Re: Resto/Rebuild 1973 Johnson 40hp!

Well, you can use an impact wrench to take it off but don't use one to put it back on, you'll need a torque wrench for that. Most use a strap wrench to hold the flywhheel to remove and reinstall the nut. Just Google "strap wrench" and plenty of suppliers will come up.

 

[PaulO]

Re: Resto/Rebuild 1973 Johnson 40hp!

I would only undo the top nuts off the lower cover shock absorbers (4 of them). Two of mine broke off from underneath the s/absorbers at the rear but because they are so corroded in I just left them there. They are still stuck hard.

BTW It looks like the head has been overheated. Is it seized??

 

[TN-25]

Re: Resto/Rebuild 1973 Johnson 40hp!

So what does everyone use as a motor stand to hold/run these things? I do not have a boat to hang it from. Pics of what ever you use would be great. Thanks!!

I bought several of these authentic reproduction OMC motor stands off an e-Bay vendor, plus I have a couple more genuine old ones (an early style 1949 to 1951 type, plus a pair of mid 50s bronze ones which are the same as the ones pictures below except for emblem style and color). Try searching e-Bay for outboard motor parts and accessories. I can't remember the vendor but he is in Michigan.That style of stand was used for all motors through the 40 horse motors such as yours (nice score BTW).

 

[BoatingCop]

Re: Resto/Rebuild 1973 Johnson 40hp!

Thanks for the pictures of the stands. Well since I', at a stand still today due to the starter not being fixed yet and waiting on parts, I'm going to make an actual stand for the motor out of 2x4's and 2x6's. Will have pics later! Also, my OMC service manual got here and it has so much info it's unreal. It really blows the other manual out of the water!

 

[BoatingCop]

Re: Resto/Rebuild 1973 Johnson 40hp!

I actually got the stand built!! It's not pretty by any means or as strong as some that I've seen but it works good enough for me. I''ve never been good with carpentry which was why I was a little scared lol. I based it off of the plans that "dh4winn79" used. It's not as strong or as pretty as his but it holds the motor just fine.

I have the puller on the flywheel right now. It's not budging so I'm gonna leave it for a few hours or over night.

Tomorrow I'm going to pull the lower unit and inspect the water pump and everything. How will I know whether or not to replace the whole housing as opposed to just replacing the impeller? Am I looking for grooves and any scoring in the pump housing, or would yall just reccomend replacing the entire thing? Thats probably what I was going to do, but wanted an opinion. Thanks for all the help so far. Tomorrow I'm ordering the points, condensers, coils, carb rebuild kit, and water pump.

 

[jasper60103]

Re: Resto/Rebuild 1973 Johnson 40hp!

I normally replace the entire water pump if possible. Did you find a waterpump kit for this motor?

edit: oh, I found one, but $127 is kinda spendy. Inspect the water pump first.

http://www.marineengine.com/newparts/part_details.php?pnum=OMC0379774&ptype=&Engine=&Model=

 

[stevo10081984]

Re: Resto/Rebuild 1973 Johnson 40hp!

use a rubber mallet to get the flywheel off, put tension on w/ the puller and then a few good whacks w/ a rubber mallet and it will pop right off....

 

[BoatingCop]

Re: Resto/Rebuild 1973 Johnson 40hp!

I normally replace the entire water pump if possible. Did you find a waterpump kit for this motor?

edit: oh, I found one, but $127 is kinda spendy. Inspect the water pump first.

http://www.marineengine.com/newparts/part_details.php?pnum=OMC0379774&ptype=&Engine=&Model=

Thanks for the leak. I was really surprised at how expensive it was too

 

[BoatingCop]

Re: Resto/Rebuild 1973 Johnson 40hp!

I made some headway today. I was able to get the flywheel off pretty easily this morning after a few taps with the hammer. I looked at everything and found that everything appeared to be clean and shiny as if it were new. Just because I doon't know anything about its history I'm still replacing coils, points, and condensers. That brings me toa a question. It said something about a timing light in the manual. Thats not a nessesity is it? Becuase it also said something about just using feeler gauges and gapping it. Is there any timing involved that I have to do when I remove the armature plate? Or do I even need to remove the plate? It'd like to not have to take it off if at all possible so I don't screw anything up.

I then removed the carb and kind of looked at it. I'm sort of intimidated by the idea of rebuilding it myself although it doesn't seem like much could go wrong. Funny thing happened though when I tried to take the cap off for the slow speed needle valve. The whole valve came out!! It had something around the threads with a rubber like texture that came out as well. The retaining nut was still in place. I then realized whoever worked on this engine before did not screw the valve in, they rather just slid it in. Does this hurt or change anything?

I then got to work on the lower unit. I removed it and ffound no gasket where it mated to the engine. Is this normal? Also tons of mud dobbers nests came out of the exhaust!

continued on next post...

 

[BoatingCop]

Re: Resto/Rebuild 1973 Johnson 40hp!

...I then removed the prop and saw a lot of grease around the prop shaft where it goes into the gearcase. Does the gearcase have to be taken apart to replace the prop shaft seal?

I then got on to the water pump. I scared the hell outta myself though and am still worried. When I pulled the impeller up off of the shaft, the shaft raised up with the impeller!!! I immedeatley put the shaft back down and tried to rotate it to where I could hear it faall into place, but I never felt it fall back into place. Did I just screw up my LU? I put it in gear and spun the shaft and it seemed to spin the prop shaft. I didn't notice the shaft wanting to pull out when I droped the LU from the motor. It all dropped nice and easy too.

The impeller seemed old, hard, dry, and cupped. There are also grooved that I can feel in the pump housing

I also noticed that I couldn't get the bottom plate off of the lower unit. I don't imagine that this plate stays. I tried to pry on it with a screw driver but I stopped because I didn't want to bend it. Also, no seals were to be found on the pump housing or anywhere. Did they just all deteriorate to where it appears none were ever there?

Also, I haven't draained the lower unit yet because I can't get either screw out!! My screw drivers are too small so I used a wood chisel that fits perfectly but still doesn't budge even after a few taps with thhe hammer. Any ideas? Thanks for all the help so far! I'm having a lot of fun with this!

 

[jasper60103]

Re: Resto/Rebuild 1973 Johnson 40hp!

I had trouble with frozen drain/fill screws.
An impact screwdriver works great at getting those out.

 

[1946Zephyr]

Re: Resto/Rebuild 1973 Johnson 40hp!

I wouldn't replace the coils. I think they look just fine. I would however replace the spark plug leads though.

 

[wilde1j]

Re: Resto/Rebuild 1973 Johnson 40hp!

I would replace the whole water pump, and yes, the wear place comes off too. The wear plate and pump housing are too grooved to reuse. You may find some of the sticky stuff under Top Secret Files helpful, beside the shop manual.

 

[BoatingCop]

Re: Resto/Rebuild 1973 Johnson 40hp!

Thank you for the replies. I ordered everything but the spark plug wires. I couldn't find any that were pre made for my engine. I will look at the connection to the coil and she what kind of connected to use and make my own if possible. I'm now just waiting on all my parts to get here, including the new water pump.

Does anyone have an opinion on the drive shaft though and if I messed anything up? Thanks

 

[PaulO]

Re: Resto/Rebuild 1973 Johnson 40hp!

I found what you are describing about yours with mine. Once the pump housing comes off the whole drive shaft comes out of the lower leg. I found mine went back in quite easily. There is a spline on the lower drive shaft that will slide straight into the pinion gear.

I would put your gearcase into gear and turn the shaft to see what happens. There shouldn't be a problem. Mine is a 1971 model 40RL71G.

 

[BoatingCop]

Re: Resto/Rebuild 1973 Johnson 40hp!

I found what you are describing about yours with mine. Once the pump housing comes off the whole drive shaft comes out of the lower leg. I found mine went back in quite easily. There is a spline on the lower drive shaft that will slide straight into the pinion gear.

I would put your gearcase into gear and turn the shaft to see what happens. There shouldn't be a problem. Mine is a 1971 model 40RL71G.

Thanks for the reply! Mine slid back in but I didn't feel a click or anything. When I put it in gear the prop spins so I figure I'll be ok. Glad to hear I'm not the only one this has happened to! Thanks!

 

[BoatingCop]

Re: Resto/Rebuild 1973 Johnson 40hp!

I got my starter rebuilt today and got it put on. I spins the engine over perfectly. I then went to check compression. #1 checked at 125. I went to check #2 and the fitting for my tester got stuck in spark plug hole as if it stripped it!! I only threaded it in by hand know it wasn't cross threaded. Now I have to pull the head. Oh well. The head gasket could prolly use a changing anyways, plus I can inspect the inside of the engine. Pics tomorrow.

 

[jasper60103]

Re: Resto/Rebuild 1973 Johnson 40hp!

I got my starter rebuilt today and got it put on. I spins the engine over perfectly. I then went to check compression. #1 checked at 125. I went to check #2 and the fitting for my tester got stuck in spark plug hole as if it stripped it!! I only threaded it in by hand know it wasn't cross threaded. Now I have to pull the head. Oh well. The head gasket could prolly use a changing anyways, plus I can inspect the inside of the engine. Pics tomorrow.

You know, the same exact thing happened to me. The compression tester was a loaner and I believe it buggered-up my threads. I replied on your other thread how I fixed the problem.

 

[1946Zephyr]

Re: Resto/Rebuild 1973 Johnson 40hp!

Spark plug wire is usuallly sold by the foot at your loacal marine supply. If not, try Sea-Way in Seattle.

 

[BoatingCop]

Re: Resto/Rebuild 1973 Johnson 40hp!

Ok, thanks!