throttle linkage for 1978 Mercury 1150 outboard

[eplankell]

Greetings,

I have two questions I would like to ask:

1) I have a 1978 Mercury 1150 outboard engine. It's an L6 with three WMK25 carburetors. After servicing the carbs, I accidentally broke the plastic throttle linkage assembly between the upper and middle carbs as I was re-installing them on the engine. The part I need is #12-53720A2, but so far my web searches have all said this part is no longer available. Does anyone happen to know if there is a suitable replacement part that can be used in place of this part on these particular carburetors?

2) Following removal of the flywheel in order to access the carbs, I noticed that there is a crack through one of the four bolt holes in the upper end cap assembly on the L6 powerhead. The result of this crack is that the end cap is now held by only three bolts, the fourth bolt holding only the small triangle of metal beneath it. My question is will this affect the operation of the motor, and should I consider replacing it?

Thanks!

Eric

 

[Chris1956]

Re: throttle linkage for 1978 Mercury 1150 outboard

Eric, That plastic throttle piece was so common for so many years, I would be surprized if you can't get it. A used parts place will certainly have one.

The good news about the end cap is that the seals are around the center part, so it will still likely seal. What/how did it break?

 

[eplankell]

Re: throttle linkage for 1978 Mercury 1150 outboard

Hi Chris, and thanks for your reply.

My brother-in-law suggested the same thing for the throttle linkage - look for used. I plan to check around this weekend.

Regarding the end cap, it's cracked immediately past the bolt, so that the bolt is only holding down the small piece of metal directly under the bolt. I'm not sure how or when it cracked. I bought the boat/engine used a few years ago and it may have came that way, but I couldn't see it under the flywheel. However, it may have cracked when I removed the flywheel. Instead of using the recommended puller, which pulls the wheel from the middle, I used the type that pulls the wheel from the edges with 3 arms. Needless to say, this caused significant flexure of the wheel before it finally came loose in a spectacular fashion! It doesn't seem like this would have stressed the end cap as all the pressure was on the end of the driveshaft and on the flywheel, but who knows.

The reason I'm working on the engine in the first place is that I've had problems with it bogging down. In a nutshell, it's always taken a while to get started, but once it does, I can throttle up to speed no problem. However, sometimes after stopping, I have trouble getting it to throttle up past idle. It will start, but once I put it into gear and try to rev the engine, it will just barely putt along. Then, out of the blue it will surge up to full speed. I had the wiring harness replaced early on due to significant deterioration. Now I'm suspecting it's something with the fuel delivery. I pulled the carbs - they looked to be in good shape, but I went ahead and cleaned them and replaced the gaskets. I've got all but the top one back on. I' figured I would also check the fuel pump and line next.

Any other suggestions you or anyone else has would be appreciated.

Cheers!

Eric

 

[bullbat]

Re: throttle linkage for 1978 Mercury 1150 outboard

where ya located at i have about 3 sets of those linkages just for that same reason they get old and break easily

 

[eplankell]

Re: throttle linkage for 1978 Mercury 1150 outboard

I'm in Champaign, Illinois. I actually came up with a fix that I'm going to try out. I found some two-part self-hardening putty that I molded around the two halves. It's hard as a rock now. I'll keep you in mind in case it fails.

Thanks!

 

[jimmbo]

Re: throttle linkage for 1978 Mercury 1150 outboard

Hope it doesn't fail on the far side of the lake

BTW. I would consider the flywheel toast. It wasn't designed to pulled off that way.

 

[Elpy54]

Re: throttle linkage for 1978 Mercury 1150 outboard

Im interested in a linkage if anyone has one. Thanks