'58 johnson lower unit question

[oaklander]

I have what I think to be a 1958 25 hp Johnson Model # RD-17 ser# 1240109
getting what appears to be water mixing with the lower unit oil. I have changed the bearing and the seals and fixed the worn area in the shaft at the water pump which helped, but lower unit oil turns milky after a brief run (apprx 30 min). There doesn't seem to be much separating the oil from the water in the lower unit except for the seal and the bushing. Is it normal for this motor to have the oil and water mixed? Is there anything more we can do to help it? The powerhead runs great otherwise.

 

[freddyray21]

Re: '58 johnson lower unit question

did you change the shift shaft seal? How did you fix the worn area? It would take a very skilled welder to fill in a small groove caused by the seal and get it perfectly round. If not perfectly round it will leak.

 

[F_R]

Re: '58 johnson lower unit question

RD-17 is a 1955, not '58. Did you replace all of the seals? Drive shaft seal, prop shaft seal, spagetti seal, o-ring, shift rod seal?

If it is showing water after only 30 minutes, it must be the drive shaft seal. Any others leaking that badly and you would see it running out.

 

[oaklander]

Re: '58 johnson lower unit question

Thanks for the response.
Freddyray21, To repair the the shaft, I turned the worn area of the shaft to a smaller diameter then used a steel epoxy to build up the area, then turned the epoxy down to the correct diameter. No welding, but I thought about metal spraying. I did replace the drive shaft bearing and seal.

 

[oaklander]

Re: '58 johnson lower unit question

Thanks for the response.
F R I did replace the drive shaft seal and the bearing. One thing that did raise an eyebrow , the bearing went into the hole with zero resistance. I would have thought it would have been tighter fit.

 

[F_R]

Re: '58 johnson lower unit question

It should have been a press fit. Whether it will cause a problem depends on just how loose it is. If it is a slip fit and not slopping around too much you can fix it in place to prevent it from spinning with some Loctite #680. That is exactly what it is made for.

 

[asdasc]

Re: '58 johnson lower unit question

Another thing to check is that the lower unit came from the same year motor. I have found that the lower units are pretty interchangeable as a unit between many of the motors for many years, but that there were changes so you can't always take parts from one and mix them with parts from another. Get the measurements or part numbers off them and compare them with the parts manuel or post them on line here and see if you ordered the seals for the right lower unit.

 

[HHinNC]

Re: '58 johnson lower unit question

Following this thread, I have a question: How tight is the seal supposed to be on the shaft? Fairly snug? or just a light slip fit?

 

[freddyray21]

Re: '58 johnson lower unit question

all the ones I have done have had to be tapped in and would not slip fit. It's quite possible you got the wrong seal. You did not indicate whether you replaced the shift shaft seal. If your drive shaft seal is that sloppy then that is your problem imo.

 

[oaklander]

Re: '58 johnson lower unit question

response to Freddyray21
The new drive shaft seal was a snug fit on the shaft and had to be tapped into the lower unit. The bearing was a loose fit in the lower unit. The bearing was a good fit on the shaft. (Maybe .001 to .002 clearance.) If that has any bearing on the problem. (no pun intended).These products were purchased from a local marine dealer. The only books they had went back to '62 and the mechanic said that a '58 and a '62 used the same bearing and seal. Now I find out I have a '55 could this be the problem.

 

[oaklander]

Re: '58 johnson lower unit question

response to Freddyray21
I did not replace the shifter shaft seal, only the drive shaft seal

 

[oaklander]

Re: '58 johnson lower unit question

response to Freddyray21
The new drive shaft seal was a snug fit on the shaft and had to be tapped into the lower unit. The bearing was a loose fit in the lower unit. The bearing was a good fit on the shaft. (Maybe .001 to .002 clearance.) If that has any bearing on the problem. (no pun intended).These products were purchased from a local marine dealer. The only books they had went back to '62 and the mechanic said that a '58 and a '62 used the same bearing and seal. Now I find out I have a '55 could this be the problem.

 

[freddyray21]

Re: '58 johnson lower unit question

should be the same seal kit according to the parts people. I misunderstood as I thought it was the seal, but after reading I read it wrong. There should not be a lot of play in the driveshaft as a wobble will cause a major leak. You have still never indicated whether you changed the shift shaft seal?

 

[HHinNC]

Re: '58 johnson lower unit question

per Oaklander:
response to Freddyray21
I did not replace the shifter shaft seal, only the drive shaft seal


Does that mean that the water can get into the lower unit through the shift shaft seal if it is bad? Would this be enough to turn the water milky after a 30 minute run?

 

[oaklander]

Re: '58 johnson lower unit question

response to Freddyray21
I did not replace the shifter shaft seal.

 

[freddyray21]

Re: '58 johnson lower unit question

sorry missed it again. I need to take a reading comprehension test. The shift shaft seal is a major offender for leaks I have found. You need to replace it.

 

[asdasc]

Re: '58 johnson lower unit question

I need to take a reading comprehension test.

I think you just did!

I also agree with your assesment. You need to replace the shift shaft seal. It is REALLY easy once you get past the fear and figure out how to do it.

Do a search on thread topics started by me and it shows pictures about how I did it with a spade drill bit. Works great if yours is the same, and I think it is.

 

[oaklander]

Re: '58 johnson lower unit question

I am new to this. How do I get TO these threads from here.

 

[asdasc]

Re: '58 johnson lower unit question

Click here:

http://forums.iboats.com/showthread.php?t=277190

What I do is click on my name ASDASC and it allows you to go to all posts by me. This works for anyone.

Good luck with it!

 

[oaklander]

Re: '58 johnson lower unit question

Response to ASDASC,

Sorry I did not get back earlier my computer just quit, but I am back up. thanks I found the threads and the info should be very helpful. Thanks to all for the help.