Topic: 1957-58 Mercury mark 10 impeller questions – Antique Outboard Motor Club,Inc

This topic has 14 replies, 8 voices, and was last updated 6 years, 8 months ago by labrador-guy.

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March 28, 2018 at 1:26 am #9508
davesko
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Hi all, My grandson was just given a beautiful Merc Mark 10. We got the motor running great and it pumps water ok but we were told the old impeller is 10 years old and we want to replace it to avoid problems down the road. I have done many Omc and newer Merc impellers but this one is clearly not so easy. Can anyone give tips,advice or where we can buy or obtain the special tools needed. My research has shown this job to be involved but I want to make sure it’s taken care of before he uses it regularly. Thank you in advance. Dave
March 28, 2018 at 2:25 am #73145
david-bartlett
Participant
Dave,

Get a copy of Mercury’s shop manual. You can make what you need to do the impeller. These are very cool motors and as far from a conventional OMC as you can get.

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March 28, 2018 at 10:06 am #73149
billw
Participant
US Member
Here are some pictures of the real tools. They seem to be available at this website:

http://www.johnsmcintoshvintagemercuryo … Tools.html

One tool they don’t sell is patience. You will need it for this job. If you have that, and enough mechanical skill to do other impellers, you can do it. Just be advised that it’s not going to happen in an afternoon. Don’t get me wrong: The Mark 10, also known as an "automatic transmission" engine, is one of my favorites. I have at least 25 of the type and have done at least as many impellers. It still takes me a long time to do it right.

One thing I don’t show in these pictures is my trick for cleaning out the area where the water pump cartridge resides. I have two small wire wheels that fit in an electric drill. One is a side wheel and one is an end cut brush. I chuck these into a 12" drill extension, to clean all the corrosion and gunk out of the drive shaft housing cavity where the pump goes. This makes things a lot easier to put back together, without force or cuss words.

Long live American manufacturing!
March 29, 2018 at 1:36 am #73177
vixbit
Participant
AOMCI member John McIntosh sells the tools needed and is also an excellent source for information. He has done a Mark 10 and Mark 15 for me.
March 29, 2018 at 10:23 pm #73219
davesko
Participant
Thank you for all the info, I don’t think buying the tools would be an option. Hoping to find a member close to me(Hershey Pa) that could possibly do it. Not sure i have one close but if not making the tools seems reasonable. Thanks again
March 30, 2018 at 9:33 am #73238
billw
Participant
US Member
Homemade tools can be as simple as a piece of pipe with notches cut in the end. I just showed the real tool options to give you an idea of what goes on. The real tools DO make it easier and don’t cost much more than taking your wife out for Valentine’s Day dinner, though.

Maybe you could trade the Mark 10 for an OMC 10 of the same vintage. They are a lot more service-friendly and might get your grandson started out on the water on a more positive, less frustrating note. When I was a kid, I wouldn’t have had the patience for a Mark 10; and I suspect it would have gotten me just far enough away from home to get me into trouble, before something went wrong.

Long live American manufacturing!
March 30, 2018 at 12:11 pm #73240
mercuryman
Participant
There use to be a video on You Tube a demo of changing impeller. I did it twice and made the tools needed. Its not easy.
March 30, 2018 at 5:12 pm #73251
labrador-guy
Participant
US Member
I have done this once so this was a learning experience for me. I purchased a Sierra impeller #18-3008. It has a rounded key way, you need to square the slot up with a small flat file. It fits perfectly with a little filing. I made the tools I needed as I went. A flat bar about 1 1/4 wide took care of the spanner nut. A tool to pull out the impeller cartridge was a little harder to figure out but a little patience and things worked out good. I also pulled the power head off. Some people say you can change the pump without doing that but I did. As you can tell from the pictured I mounted the leg back in the stand upside down. Really worked great for working down in that hole. Pay close attention as to how the shifting paws go in the case, maybe take some pictures. Also there is a small drain hole on the gear case ahead of the propeller. Make sure it is not plugged. It brings water up the leg to the impeller cavity so it does not start dry. I need to get a picture of that 1/16 hole and post it. My motor is buried in the shed for now.

Loveem or hateem these Merc’s are interesting!
hope this helps
dale

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March 30, 2018 at 10:41 pm #73259
seakaye12
Participant
US Member
There is a really informative video on youtube covering this exact repair. I don’t know if it was done by a member or not; the person seems to know what he’s doing….and shows a lot of what is involved.

No OMC….

https://www.youtube.com/watch?v=lB4fkM0wvPk
March 30, 2018 at 10:49 pm #73260
david-bartlett
Participant
Chuck,

That video is helpful in that you get to see the pieces in their locations.

I have to question his use of a gasket between the lower unit gearcase and leg as none is called for and can affect the end play which is critical in these.

My opinion is to use all the resources available and do your research before you start.
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