Outboard motor throttle linkage repair options

[kpgraci]

I have an older 8.5hp merc 2 stroke (circa 1985). It still runs strong but has a problem with the throttle linkage.

I don't have any pics of the problem area, which I'm sure would help to explain the issue, but here goes.

I'm sure most outboards have a similar linkage setup, the throttle handle turns a gear that converts the horizontal rotation of the hand grip to a vertical shaft that controls the carburetor.

The problem is that the square hole of the gear that rotates the vertical square shaft is rounded so it does not actually rotate the shaft anymore.

As a result I have to pull the cover off and manually control the throttle arm, putting my fingers near the spinning flywheel of death.

So the problem boils down to repairing the round hole that should be square.

What I've come up with so far is this:

1. Get replacement parts. Problems is it's an old motor plus I tried to remove the square shaft once, and although I consider myself a fair mechanic I could not figure out how to actually remove the shaft form the engine - it seems to have been either been crimped on or slid on while the motor was detached from the lower unit.

2. Hook up an external throttle. This bypasses the linkage problem as the throttle cable hooks directly to an arm on the square shaft - but I don't really have a place in the boat to mount a throttle handle.

3. Repair it. This is what I want to do, I need to strongly attach the round hole/square shaft union. I've considered JB weld, drilling and pinning, inserting shims, clamping, and combinations of each.

I'm sure the forces are pretty high on the joint, plus the environment is oily and experiences a lot of vibration.

Anyway, if anyone can think of something I have not I would like to hear it.

 

[Winkfish]

Ken, does the gear with the (formerly) square hole come off fairly easily?

How about a thin nut, to fit over the square shaft, JB Welded to the gear over the round hole?

Also, Bayou Outboards in Metairie is a great place. I assume they sell parts - might have some spares from all the work they do on outboards.

Do you want to still be able to disconnect the gear from the shaft? If not, you might want to JB Weld the pieces together to last (hopefully) until the motor completely craps out.

 

[kloudie1]

Check out these guys, Ken.. http://www.crowleymarine.com/mercury-outboard/parts/297_100.cfm
Looks like the arm hinge has to be removed and the gear and shaft are the together.. ?? I don't know if that is the correct end or model but you should be able to find what ya need there.. Good luck !

 

[larryw]

Marine-Tex!!

 

[kpgraci]

Ken, does the gear with the (formerly) square hole come off fairly easily?

Well, I tried once and failed, but that's not to say it cant be done. I think the square shat has done it's share of rounding as well, but I think some sort of rig like that may have merit.

 

[kpgraci]

Check out these guys, Ken.. http://www.crowleymarine.com/mercury-outboard/parts/297_100.cfm
Looks like the arm hinge has to be removed and the gear and shaft are the together.. ?? I don't know if that is the correct end or model but you should be able to find what ya need there.. Good luck !

I've looked at similar exploded views and none seem to match 100% to my engine. I guess I need to find a model or sn somewhere.

I had the motor pretty far apart trying to remove the square shaft only to find what looked like a retaining clip or washer that was made into the shaft - I didn't want to force it and break something. A parts view for my model would be valuable.

 

[Ted]

If the part you are trying to make a repair to is aluminum, you can try a product called Durafix. I've used it with great success to repair holes in a boom. My first experiment with this product was to try to repair a hole adjacent to the spark-plug in an outboard engine cylinder head . The hole was 1/2 inch diameter and I really didn't think it would work. I was able to fill the hole and the engine ran perfectly for years. I was totally amazed that it actually worked as claimed. Check out this video demonstration of the product. There are also another 6 video demos of the product on YouTube. No affiliation whatsoever.

http://www.youtube.com/watch?v=jijW310xvp4&feature=related

 

[Lee Coller]

Find a mercury dealer and see if they can get parts. A lot of those old engines still have parts manufactured for them (I was getting parts for my 66/67 Johnson 6 horse into the 90's).

 

[Winkfish]

Ken,

I just remembered another place in Harahan - The Boat Doctor. I think the owner's name is Hank. He's great, and if there's a solution or a part you need, he's the one to do it. Also, on RodNReel.com, there are 2 great forums - "A Question For Mechanics" and "Boats, Motors, And Boating Equipment." Post your question there, you'll get LOTS of good responses.

 

[kpgraci]

My first experiment with this product was to try to repair a hole adjacent to the spark-plug in an outboard engine cylinder head . The hole was 1/2 inch diameter and I really didn't think it would work. I was able to fill the hole and the engine ran perfectly for years.

Huh, that is amazing. I'll check it out.

 

[kpgraci]

Ken,

I just remembered another place in Harahan - The Boat Doctor. I think the owner's name is Hank. He's great, and if there's a solution or a part you need, he's the one to do it. Also, on RodNReel.com, there are 2 great forums - "A Question For Mechanics" and "Boats, Motors, And Boating Equipment." Post your question there, you'll get LOTS of good responses.

Cool. Thanks.

Just called the Boat Doctor...They only work on >= 40HP

...and, RonNReel seems to not be accepting new registrations... :bang:

 

[kenn]

I'd try hard to get the proper replacement part. Or a parts motor with a good linkage.

There's too much force exerted at the center of those gears for a goop-type fix to work for long.

Without a picture I don't know what clearances you have but you might be able to fabricate a sort of plate washer with the proper square hole that you could then screw or pop-rivet to the gear with the stripped hole.

 

[kpgraci]

Got the SN - its 3281189, that makes it a 1972...wow. Well, the boat is a '73, original sails and motor..hey...its a classic.

After looking at the linkage closely there seems to be a lot of play where the vertical shaft seats in the case...as well as the rounding problem. I don't think it will be difficult to fabricate a fix if I can tear it apart. All the part houses I've seen start with sn around 1985ish up. I was hoping for a easy, in place fix, but I'm gonna have to pull the motor off and put it in my shop while I mess with it.

Pics don't really show much but since I took 'em I'm posting 'em.