1962 Johnson 28hp

[KRRNY4/6]

I have a 1962 Johnson 28hp is pretty good condition. I have replaced the coils, points, changed the oil in the lower unit, rebuilt the fuel pump and carb.

It ran well for a while and then was sluggish. I thought it was the carb adustment so I adjusted the high and low speed needles. Now I can't get it to fire up????

Once in a while there is a bit of black oil coming out of the water in take on the left side of the leg. Is this normal?

Shaun

 

[jay_merrill]

Re: 1962 Johnson 28hp

This is a pretty simple motor so it isn't complicated to figure out what is going on. Go back and set the needle valves per the factory setting. I don't have a manual on a 28hp OMC but the settings are probably the same as for the 33hp model. Gently seat your needle valves and then back out the high speed valve to 3/8ths of a turn, and your slow speed valve to 1-1/4 turn.

To adjust these valves, run the motor in gear and adjust the high speed valve first. If you have a test wheel or have access to one, you do this in a barrel or at the dock. If you do not have a test wheel, you will need to have a friend drive the boat for you, while you do the adjustments. With the motor at WOT, adjust the HS valve until you obtain peak rpm. Once this is accomplished, the slow speed valve can be adjusted. This is done in gear, with the motor running at 700 - 750 rpm. Once again, adjust for peak rpm but consider the smoothness of the idle too. If the motor "sneezes" (makes an intermittant "chuffing" sound), the mixture is too lean and you need to enrich slightly. For all of these adjustments, allow 15 seconds between changes to insure that the motor has enough time to react to what you did.

If you motor is still running poorly after doing the above, its time to check some other things. The first thing that I would do is to check the compression and, in fact, it makes some sense to just go ahead and do so right away.


PS:Text edited to fix mistake per FR's post. "Cyber beer" sent to Shaun for my inattention and general screw up!

 

[F_R]

Re: 1962 Johnson 28hp

Good advice Jay, but you got the presets backwards. Should be 3/8 on high speed (lower one) and 1-1/4 on slow speed (upper one) It would flood like crazy with 1-1/4 on the high speed.

 

[jay_merrill]

Re: 1962 Johnson 28hp

Thanks for the catch, FR. That's what I get for trying to write something quickly, before meeting with my attorney about something that is ticking me off!

 

[KRRNY4/6]

Re: 1962 Johnson 28hp

Jay,

Thanks for the quick input. I recleaned the carb and re-installed then reset the needles as per the suggestions. The system was dry but once it got wet it still would not fire up. Thinking now it was the points and/or coils I pulled the fly wheel. My fly wheel does not have the access cover to set the points. The wheel has to pulled each time. The outline is there in the wheel casting of where the the cover and screws could go but's soild.

Once the fly whhel was removed I found part of the problem. The woodrooffe key was sheared in two pieces so the fly wheel was free spinning on the power head shaft. I installed a woodroofe key off an old 40HP that I have and torqued everything down. Restarted the motor and it fire on the first attempt. It seemed to run fine in the test tube (prop. off) at full throttle, idle etc...Started it off and on for few days it stated on right up every time.

Put the prop on and headed to the lake. Started right up and we headed out. problem: no speed under full load ie: full throttle. Discovered it's running on one cylinder. I pulled the head off and the top is firing the bottom one is not.

While looking at the motor I noticed a small amount of water in the pan right below the head. Not a lot of water but some water. There is a small hole in the pan where the water was collecting and the water was draining out through that hole. With the head off the casket looked OK so I am not sure where that water is coming from?

I think now when the woodroofe key was sheared some small metal pieces might have shorter the coil or they are interferring with the point.

I have to re-pull the flywheel and see what's up with that non-firing cylinder. I don't have the compression tool so I can't check the compression on thst cylinder.

Sorry for the long comment...

Shaun

 

[F_R]

Re: 1962 Johnson 28hp

Whatever you find, check out that flywheel better. Keys don't shear unless something is wrong. If the flywheel and/or crankshaft tapers are damaged, or the key slot is damaged, you are SOL. Otherwise, when you install the flywheel, make sure the tapers are clean and dry and use a torque wrench to tighten that nut to 100-105 ft/lbs. If you keep shearing the key you are sure to damage the parts. (See above note on SOL.)

 

[KRRNY4/6]

Re: 1962 Johnson 28hp

Whatever you find, check out that flywheel better. Keys don't shear unless something is wrong. If the flywheel and/or crankshaft tapers are damaged, or the key slot is damaged, you are SOL. Otherwise, when you install the flywheel, make sure the tapers are clean and dry and use a torque wrench to tighten that nut to 100-105 ft/lbs. If you keep shearing the key you are sure to damage the parts. (See above note on SOL.)

FR,

Thanks. I did check the wheel, the taper and the key channel carefully all looks good. There is a minor scuff on the wheel but it is not rough to the touch. I did not have a troque wrench when I first re-installed the fly wheel last season but I did tighten it down really well. Apparently not well enough! I have since acquired a good torque wrench and used it when I installed the new key the other day.

Shaun

 

[jay_merrill]

Re: 1962 Johnson 28hp

I agree with FR that its a good idea to figure out why the key sheared. Usually it is because the taper and the inside of the flywheel were not cleaned of all grease, etc., or because the flywheel was not seated properly and torqued sufficiently. Sometimes both are working against you in combination. One of the things that I do when reinstalling a flywheel is to stand on a stool with a flashlight, looking straight down into the slot on the flywheel to make sure that it is exactly lined up with the key. I then lower the flywheel and watch the key slide into the slot, thus insuring that I have the flywheel properly seated. My next step before installing the nut and torquing, is to tap the flywheel down with a rubber mallet.

You might also consider whether to top crankshaft seal is leaking because that can cause ignition problems also. I would say, however, that this problem most likely wouldn't affect one set of points only.