No spark on Johnson TD, TN, and HD Engines

[5oldjohnsons]

Hi everybody. Im new to this forum and somewhat new to outboards. I have inherited some old outboards from my grandfather, unfortunately none run.
HD25 serial #724061 1949
TN26 serial #833771 19?
TD20 serial #536227 19?
TD20 serial #536269 19?
All of them have spark on just the top cylinder. I took a coil off one td20 and swapped to the other td and still no spark on bottom cylinder checked all wiring that is visible but didn't see anything. Primary coil resistance is 0 ohms, secondary for both coils is about 3.5k. Point gap set to .020. Points are clean. Wire resistance is 0 ohms. Tried different spark plugs. If anyone has any help for me to try it would be appreciated. Thank You

 

[Big flop]

Re: No spark on Johnson TD, TN, and HD Engines

Did you use ohms meter on points open to
closed checking for good contact?

 

[HighTrim]

Re: No spark on Johnson TD, TN, and HD Engines

This is really the website you want for troubleshooting your TN/TD/HD series motor. They are a bit finicky, regarding the carb and gearcase, but once you know your way around them they arent that bad. The impeller is NLA, but if you get an impeller from a 50s vintage 5.5hp, it will work if you bore out the center a bit so that it fits over the driveshaft. They dont need to be bored much.

http://www.pochefamily.org/outboard/CarbService.html
http://www.pochefamily.org/outboard/

 

[HighTrim]

Re: No spark on Johnson TD, TN, and HD Engines

This should help as well

http://hoodad.fortunecity.com/tnlowerunit.html

 

[5oldjohnsons]

Re: No spark on Johnson TD, TN, and HD Engines

Yes I used a meter to check point contact also

 

[HighTrim]

Re: No spark on Johnson TD, TN, and HD Engines

This will get you going with the ignition

http://www.pochefamily.org/outboard/Coils.htm

If those coils are original, save yourself some troubshooting and replace them. Refrsh the mag plate with new coils, condensors and points and she will be sparking like crazy.

 

[steelespike]

Re: No spark on Johnson TD, TN, and HD Engines

The TD and HD coils are pretty much bullet proof. The TN may use the plastic coils like on similar E/J of the period.These likely may have failed.Any cracks or discoloration replace.The TD and HD have little push rods that operate the points they sometimes get gummed up over time and drag so the points don't operate right.

 

[5oldjohnsons]

Re: No spark on Johnson TD, TN, and HD Engines

Ok thanks guys. I'll do a little more checking but probably just end up replacing ignition parts. Its not going to be cheap for all four....

 

[Mas]

Re: No spark on Johnson TD, TN, and HD Engines

Shine up the points and make sure there is zero oil on them...it will work! It would take too much money to replace the ignition for that vintage. They use the "push points" style.

On my TN, I couldn't get spark until a bunch of tries cleaning and adjusting...now it's the best running motor I own & I didn't replace any of the ignition parts except new copper core plug wires.

Mas

 

[1946Zephyr]

Re: No spark on Johnson TD, TN, and HD Engines

Your TD-20's are 1946-49. TN-26 is 1951-52 The older motors, the thing that also fails them, are the condensors and spark plug leads too. Like steelspike says, clean the pushrods for the points completely and make sure they operate feely. Make sure the points are 100% clean

 

[F_R]

Re: No spark on Johnson TD, TN, and HD Engines

HD25 serial #724061 1949 yes
TN26 serial #833771 1950
TD20 serial #536227 1946
TD20 serial #536269 1946

Take those points apart and degrease them and polish each contact individually. Reassemble and adjust gap at .020" at widest opening. Do one set at a time so you have a sample how they go back together. Be careful, there are a bunch of little insulators to lose.

 

[1946Zephyr]

Re: No spark on Johnson TD, TN, and HD Engines

So, it appears ALL of those motors will have the same ignition system. The TN's didn't go to the universal till '51.

I second F_R's last note there. Be mindful about how the ignition system comes apart and how it goes back together.

 

[eball429]

Re: No spark on Johnson TD, TN, and HD Engines

I had a similar problem on a 1947 TD-20 and realized I had the throttle lever in the stop position when I was checking for spark. The stop position grounds out the bottom cylinder's coil. I had great spark on the top cylinder and no spark on the bottom cylinder. I moved the throttle lever to the start position and now both cylinders have great spark. Hope this helps someone!