TN28 Lower Unit

[Ronald Smith]

frankr: Do you suggest just installing the modification?

[frankr]

I don’t understand why it won’t go back together. The parts were in there before you started the project, right?

Anyhoo, I feel it needs at least the original configuration to keep water out of the crankcase. The modification keeps the water out of the crankcase AND splines. I installed a few of the mod kits back in “The Day”, as the salt water in this area would cause severe damage. Of course that was 60 years ago, and memory fades. Seems the powerhead should lift off with no problem except stuck gaskets.

[lloyd]

That’s a great looking TN28! I can tell it has very low hours as the paint hasn’t even worn off the fiber bushing where it rubs on the tower. When you get around to running it you will almost surely need new Leather Primer Seals and instructions with diagrams on how to install them. If so, send $10.00 cash and a SASE (Self Addressed Stamped Envelope) to me: Lloyd Lautner 9289 North Long Lake Road Traverse City Michigan 49685. Have fun!

[Ronald Smith]

frankr: It seems like it should just slide in, as you say, but it doesn’t. The shaft and spline are enough undersized and have enough play so that the washer and disk can move in all directions. I’ve used a dab of marine grease to try to hold them in a relatively good position; but it has to be press fitted into the receiving hole, otherwise it wouldn’t seal. So it just get there and won’t line up. I thought that I might not be aggressive enough, but its a fine line between messing up the seal I have and not pushing hard enough. Then I though that I might fineness it. So, I came up with the dowel for centering and the plastic conduit sleeve to push with. Still wouldn’t seat. Anyway, I’m at max frustration so it’s a good time to take a break. I am sure that the gasket just needs broke loose on the powerhead. I will put some pressure on that tomorrow.

Lloyd: Good to hear from you. Yes, I bought 3 sets of seals from you and so glad you are out there for the community. I have a TD20, an HD25, and this TN28. Your drawing and instructions are super. Your seals go in and the crab gets a going over next. I was just green enough to think that the lower unit, impeller, and gear grease would be a piece of cake. Then I got edumacated.

[Ronald Smith]

Update: Well, someone said that the powerhead should just lift off, and they were right. One bold, that the manual doesn’t do a good job of pointing out, goes through the base of the tiller mount. Looked until I found it. Then the powerhead just easily lifted off. Looked in and there was the notorious SPRING. This is all done on my parts/practice TN28. I didn’t want to mess the nice one up. So, I now have the spring, the plastic disk with o-ring, and the metal washer. The spring is just big enough that doesn’t fall out when you pull the lower unit. I considered hooking on to it from below, but it is sized so that I would have had to force it past the water tube. That would have distorted it so that it might not have been reusable. It starts being fun when you have success and a break through. Yes, they will easily go in from above.

The next issue is the order. frankr’s diagram shows it below the washer. I’m not too sure about that. The spring diameter is exactly the same as the washer and plastic disk, but all three are larger than the press collar which is supposed to keep them in place. Also, the metal washer and disk fell out, but the spring stayed in place. If the spring was last, it would not have staid. Still have to sort the issue of order out.

On the near mint TN28, I have to rebuild the magneto. At a minimum I will replace the coils, and clean and gap the points. Since I also have condensers I will change those. With it tore down there is no reason not to put new plug wires on it too. At that time I will lift the powerhead and drop the seals and spring in place. You guys were great. You gave me what I needed to know to keep on going when I wanted to stop. Yea for OMCI.org.

Thanks from new boy.

[frankr]

The only way it can possibly work is if assembled the way the picture shows. The spring and washer hold the plastic piece snugly against the end of the crankshaft.

[Author]

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