1958 7.5 AD 12 Johnson impeller replacement

SPK

Seaman
Joined
Nov 21, 2010
Messages
55
Hello again,
As you can see by the title of my post I am considering an impeller replacement[probably a late fall project] as the impeller seems to be working well to this point. Water is spluttering out when the motor is running. It isn't a stream like I have seen on some newer motors but it is pushing out water consistently.

I understand that an impeller change requires removing the power head and when the time comes I will have to do it.

Recently I changed the coils and condensers and wow what an improvement in the engine performance. The old coils were badly cracked and I suspect they were originals. A bit expensive here in Ontario at about 40.00 dollars each. I know they usually less expensive in the U.S.A. but sometimes the shipping can be more than the cost of a coil. I did not replace the points as they looked real good so I just cleaned them with some very fine sand paper.

If anyone can direct me to a good summary or a step by step approach to changing the impeller and related impeller parts, I would really appreciate this information.

I will likely have to order in the necessary parts to do the job so your input about what I am going to need to completely do the job would be much appreciated. I don't want to be caught missing a small part because I didn't order it.
Looking forward to hearing from you.
Sean.
Ontario, Canada.
 

jbjennings

Captain
Joined
Jul 18, 2007
Messages
3,903
Re: 1958 7.5 AD 12 Johnson impeller replacement

I'd order a lower crankshaft carbon seal and a water pump impeller, and let it go at that if the lower unit is sealed well. Just make sure you keep up with the assembly order of the parts on the drive shaft which include the carbon seal.
Putting a little grease on the impeller blades before reinstallation was a helpful tip I learned here.
JBJ
 

PatSea

Cadet
Joined
Jan 4, 2011
Messages
19
Re: 1958 7.5 AD 12 Johnson impeller replacement

I replaced the impellor on my '57 7.5 hp last winter. You're right, you have to remove the power head to get at the impellor. The job was not difficult, just keep track of the parts. I made notes and took a few photos as I disassembled. I would definitely replace the carbon seal and a small cork gasket seal the is in the same area. New gasket between the head and intermediate housing. I was able to buy all the parts from my local Johnson dealer, although he had to order them, but I had them in a week. Good luck.
 

SPK

Seaman
Joined
Nov 21, 2010
Messages
55
Re: 1958 7.5 AD 12 Johnson impeller replacement

Thanks very much JBJ. I will keep reading and researching info with respect to this topic.
Many thanks,
Sean.
 

SPK

Seaman
Joined
Nov 21, 2010
Messages
55
Re: 1958 7.5 AD 12 Johnson impeller replacement

Thanks PatSea,
I have access to a parts booklet for this motor. I trust that the parts would be listed there.
Is it possible to buy a complete kit with everything you need to do the job?
Might be simpler in the long run.
Sean.
 
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