Was given a Merc Kiekhaefer 7.5 hp

Mark42

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Oct 8, 2003
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Friend from church gave me an old 7.5 hp merc. Looked up the serial number online and found its a 1953 Merc Keikhaefer 7.5 hp. It looks OK, but was crusted with a lot of mud. When I pull the starter rope slow and easy, the prop does turn. It apparently has no "gear box". Just "off, slow, start, fast" settings. He gave me the classic line "it ran the last time we used it". Looks like it was put away wet.

Good Points:

Shows no damage, IE no dents in tank, prop is good, lower leg is not dented up.

Its a nice twin cylinder, and is fairly light for a twin.

Gas tank is part of engine shroud.

Has recoil starter.

All parts are there, including the lower engine shroud.

Problems it has:

- The "throttle" control, the lever that slides across the front of the motor, is seized.

- Most stuff seems to be seized, from the mounting bolts, to anything else.

- There is gas in the tank, and the cap won't come off by hand.

- Didn't remove plugs (very rusted) to check for spark.

So it got put in my shed, and will be next winter's project outboard.

It looks OK, and it appears that basic ignition parts are available.

My questions are:

Is this worth getting running, assuming that I won't have to spend mega bucks on parts?

Is it a good motor to put on a 12 ft tinny and run the local rivers?

Is the water pump a "hard " unit or a soft rubber job that is probably rotted away by now?


BTW, can anyone point me to a site with the owners manual, or exploded parts list? Any info that will make disassembly easier is greatly appreciated.
 

Chinewalker

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Aug 19, 2001
Messages
8,902
Re: Was given a Merc Kiekhaefer 7.5 hp

Hi Mark,
The little Rockets were fun motors! I have a couple in my stable. There were two flavors, the KE4 and the Mark 7. Very similar, but the Mark 7 was a bit more refined. Both were fairly strong for 7.5hp.

As for your questions:
>Is this worth getting running, assuming that I won't have to spend mega bucks on parts?
Yes, if you can get things apart without breaking them.

> Is it a good motor to put on a 12 ft tinny and run the local rivers?
Yes, if you go through the motor and replace what needs replacing with no shortcuts.

> Is the water pump a "hard " unit or a soft rubber job that is probably rotted away by now?
It uses a vaned rubber waterpump impeller, much like most other outboards do. It is located on the propshaft, just forward of the propeller.

>BTW, can anyone point me to a site with the owners manual, or exploded parts list? Any info that will make disassembly easier is greatly appreciated.
Get familiar with OldMercs.com (aka EastCoastMarine.com). They handle a lot of old Merc outboard parts, manuals, etc. Also, parts diagrams and lists are available online at: www.mercruiserparts.com/selectModels3.asp?type_id=MARK

- Scott
 

Mark42

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Oct 8, 2003
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Re: Was given a Merc Kiekhaefer 7.5 hp

Thanks for the info and link! I guess I will be shopping there for parts. I don't shop at iboats anymore due to their business practices.
 

Huron Angler

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Apr 7, 2009
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6,025
Re: Was given a Merc Kiekhaefer 7.5 hp

A free 7.5 merc:D Cool!

My 12 foot tinny is rated for 7.5 and sometimes I wish my 5.5 had a little more planing ability. Should be a great old motor to run. Good luck unsiezing the old motor this fall:)
 

Mark42

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Oct 8, 2003
Messages
9,334
Re: Was given a Merc Kiekhaefer 7.5 hp

Yep, can't beat free!!!

I think it will clean up real nice. This weekend I should spray all the nuts/bolts and moving parts with Liquid Wrench or PB Blaster. I used Liquid Wrench for years and its a good product.

The crank turns over without any unusual noises. Hopefully, the plugs are not rusted in the cylinder head so bad they gall the threads when they come out.

A few months of sitting with penetrating oil should make it easier to dismantle.

When i get around to working on it I'll post some pics.
 
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