Johnson TD Project

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This topic contains 15 replies, has 10 voices, and was last updated by Avatar chris-p 1 hour, 42 minutes ago.

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    adam1961
    Canada Member - 2 Years
    Replies: 356
    Topics: 77
    #169939

    I have decided to pick at a TD that was given to me. I have never looked at a TD or TN series motor in much detail, so though that it would be a good motor to learn on.
    I have read the service manual and understand the carbureation setup. That seems to be the most unique feature. I have noticed that the engine pulls over with more resistance that a CD 5HP or other similar sized engines. Compression was 60psi on both cylinders before disassembly. The crank does turn freely when one piston is near TDC and the other BDC. I have removed the powerhead to confirm that the lower unit was not causing the resistance. I pulled the head to look at the cylinders and they look OK. The resistance seems to be caused by crankcase compression when both pistons are covering the ports. There is a noticable release of air when the first set of ports are exposed. I have never worked on an alternate firing engine that uses the 3rd port design. Is this normal?

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    aquasonic
    US Member - 1 Year
    Replies: 313
    Topics: 31
    #169954

    There is a different feel to a TD than the later CD or Fisherman Models. The TD has a little more of a “thump” feel to it when the compression is released. If the motor has one of the factory wire core pull cords, as opposed to a nylon replacement, then the effect is even more pronounced. Hopefully there is no issue with your motor.

    • This reply was modified 3 weeks, 1 day ago by Avatar aquasonic.
    frankr
    frankr
    US Member - 1 Year
    Replies: 3939
    Topics: 43
    #169958

    TD has the old style starter with smaller pulley than the CD ’56-up that has the large elliptical-shaped pulley. Short story, TD pulls harder.

    60psi compression is low.

    A puff of air is normal when the ports open. In fact, it is necessary.

    Ignorance is simply a lack of education. Ignorance can be cured. There is no cure for Stupid.

    Avatar
    PAUL PENDERY
    US Member - 1 Year
    Replies: 1
    Topics: 0
    #170924

    I have a Johnson TD20 and spent a good deal of time on it this last year. Solved spark and carburetor issues (I think) but still can’t run it at low speed. Found compression is only at a little over 60 PSI in both cylinders. Is the most likely answer for inability to run at idle speed then the low PSI, and thus at least a ring job? Is there any chance it could be the low speed jet is clogged and low PSI is ok? One more bit of info, The motor seems to react accordingly to adjustments in the setting on the low and high speed valves.

    Thanks!

    Buccaneer
    Buccaneer
    US Member - 1 Year
    Replies: 2831
    Topics: 791
    #170929

    I have a Johnson TD20 and spent a good deal of time on it this last year. Solved spark and carburetor issues (I think) but still can’t run it at low speed. Found compression is only at a little over 60 PSI in both cylinders. Is the most likely answer for inability to run at idle speed then the low PSI, and thus at least a ring job? Is there any chance it could be the low speed jet is clogged and low PSI is ok? One more bit of info, The motor seems to react accordingly to adjustments in the setting on the low and high speed valves.

    Thanks!

    My best idlers in the TD and HD series Johnson are the ones with the compression
    close to, or above 70 psi compression. Doesn’t sound like your low speed circuit
    is plugged. A ring job may help, depending on the overall condition of the cylinders,
    pistons, etc. Make sure your current rings aren’t froze in their grooves first.

    Prepare to be boarded!

    Avatar
    lloyd
    US Member - 1 Year
    Replies: 83
    Topics: 0
    #170975

    Buccaneer has covered it. They need 70-75 psi to idle nice. Highest I have ever measured on those models is about 77 psi. And as he stated, make sure the rings are not stuck from sitting a long time. Use a lot of penetrating oil and warm up the block while rotating the crank forward and backwards. This may free the rings without disassembly.

    Avatar
    adam1961
    Canada Member - 2 Years
    Replies: 356
    Topics: 77
    #170977

    Hi Everyone,
    Thank you for the input. I am going to disassemble the motor to hone and install new rings. I will get to that as soon as I get the carb rebuilt. I have spark, but will replace what look to be the orignal condensors.

    Lloyd,
    Do you have the primer seals available for these? I pulled the primer out and it looks like part of it is still stuck in the sleeve. I need to look at the manual again and see exactly what came out and what is still in there.

    Adam

    Avatar
    lloyd
    US Member - 1 Year
    Replies: 83
    Topics: 0
    #170980

    Yes Adam. I still have a limited number of Primer Seals that come with complete instructions and diagrams to replace them. Getting very hard to find the proper oil tanned leather to make more. You will surely need them for your motor. Send $10.00 (cash only, no checks) and a SASE (self addressed stamped envelope) to Lloyd Lautner, 9289 North Long Lake Road, Traverse City, Michigan, 49685. Sorry if this sounds like an advertisement, but you asked, and I tried multiple times to post a classified ad on this new website without success. Good luck and have fun!!

    Avatar
    crosbyman
    Canada Member - 1 Year
    Replies: 1111
    Topics: 147
    #171002

    ADAM… DO YOU HAVE U.S. STAMPS FOR RETURN SASE…. 🙂

    Avatar
    Eric McNett
    US Member - 1 Year
    Replies: 49
    Topics: 6
    #171011

    Some of the best motors built, had a 48 TD20 idled down real nice with out anywork. Do miss that motor, have a 49 td20 under resto and a mint 52 TN27 ready for new ignition and water pump.

    Eric McNett
    Seattle AOMCI Member

    • This reply was modified 1 week, 1 day ago by Mumbles Mumbles.
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    garry-in-tampa
    Lifetime Member
    Replies: 2958
    Topics: 29
    #171199

    You may have to go to a SAE 40 wt. oil to get it to seal properly. Some knurl the skirt to enlarge it and have it hold more oil. Those small third port outboards are very sensitive to crankcase leakage at low speeds. Some won’t run with a propeller attached. With the carburetor next to the exhaust they can vapor lock in hot weather. When everything is right, there is no motor better. . .

    Avatar
    adam1961
    Canada Member - 2 Years
    Replies: 356
    Topics: 77
    #171710

    Hi Everyone,
    I have been swamped with other duties, but this project is still advancing slowly.

    The motor has one piston that has a scored area that I don’t like and the cylinders are heavily glazed. The crank is OK and one rod is a little rough for my liking. I managed to find a NOS powerhead for about what I would have expected to spend in parts….so that part will be taken care of.

    My prop shaft has a deep wear grrove in the seal area. The most current substitute for the seal is about 1/2 of the width of the original. If i set it just into the bore, I think the seal will contact a different part of the shaft. Has anyone ever used epoxy to fill a wear groove on a otherwise good shaft?

    Lloyd,
    I will look you up in the directory and phone you to make arrangements for the primer seals.

    Adam

    Buccaneer
    Buccaneer
    US Member - 1 Year
    Replies: 2831
    Topics: 791
    #171719

    I tried JB Weld on a drive shaft seal groove, and it
    help up about 5 minutes.
    Speedi Sleeves are expensive, and never the right sizes!

    Prepare to be boarded!

    Avatar
    adam1961
    Canada Member - 2 Years
    Replies: 356
    Topics: 77
    #171721

    Buccaneer,
    Did you machine the worn area and give it some texture, or apply the JB to the smooth groove? I was thinking of JB or Devcon.

    Adam

    Buccaneer
    Buccaneer
    US Member - 1 Year
    Replies: 2831
    Topics: 791
    #171723

    Buccaneer,

    Did you machine the worn area and give it some texture, or apply the JB to the smooth groove? I was thinking of JB or Devcon.

    Adam

    I slightly v’ed it out to give the JB more surface area.

    Prepare to be boarded!

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