Bad (clutch) doggie? 1989 120 Johnson.

[PaulCT]

I was out one night last week, cruising along at about 3500-4000 RPM (1989 Johnson 120 TL). All of a sudden, WHAM, it felt like I hit a log or something submerged (middle of the channel, 15 ft depth, no charted obstructions). The whole boat shuddered. I immediately throttled back. It was dark, I did use my spotlight but did not locate anything floating after a few moments search. I was more concerned to head back home rather than continue the search in the dark.

First thought through my mind is the clutch dog. After arriving home, I went through the service manual to see what kind of job it would be to change it myself. This is definitely within my capability and would consider to do so myself, though I would also price out what a local Evinrude dealer would do for the job.

I've since taken the boat out several times and nearly 100 miles without an incident. Initially just a bit to confirm, then I took a long ride down much of the length of the CT river just south of Hartford to the Long Island Sound (40 sm each way). Part throttle, WOT, no problems.

Thought I still consider a worn clutch dog as the leading cause, I'm wondering if I might really have hit a log, or submerged object.

Is it possible to have an "isolated" occurrence of clutch dog failure, which does not repeat. Or if it was indeed due to the clutch dog, is it certain to occur again (and increasing frequency)?

Now something I shrink to admit but must because of it's relevancy: at the beginning of the season I changed the water pump. I was careful (or so I thought...) not to disrupt the orientation of the shift rod (e.g., shift-rod height). However, upon installation, I had difficulty installing the shift rod pin. I could only align the pin if I engaged very slightly into gear. I did have to adjust cable to make reliable, clean shifting into and out of neutral to fwd and reverse. I had figured no damage, since I compensated the length of shift-rod offset by the amount of cable adjustment (I might be slightly off, because the travel is an arc, not a straight line). Is it not reasonable to compensate for shift rod mal-adjustment through adjustment of the cable length? Or is this a likely culprit.

thanks,

Paul

 

[Tim Frank]

Or if it was indeed due to the clutch dog, is it certain to occur again (and increasing frequency)?

I would say yes.

Before I ripped into the gear-case, though, I'd have a look for any evidence of a "strike' on the leading edges of the lower section.

 

[PaulCT]

Thank you Tim.

I've put a few more hours on, still no repeat (mileage wise ~ 120 miles). I'm approaching the end-of-season here in New England (not just yet, Indian Summer this weekend), and with no evidence of a strike, I'm planning to tear down the gearcase after I pull the boat out of the water. Avoid the potential for starting next year off with an unpleasant surprise...

I was originally planning to replace not just the clutch dog, but the forward and pinion gears as well. However, replacing the pinon adds complexity by having to shim the driveshaft. Tools in the service manual for shimming look to cost ~ $70 (P/Ns 328366 (gauge) and 328362 (collar)), plus the manual shows the fixture tool ("tool base") but I don't see any P/N for this. If necessary to replace the pinion, I will do so, and if further necessary, will purchase the proper tools.

So, a couple of questions regarding the job...

Before I committing to pinion and fwd gear replacement, I'd like to understand if it acceptable to change only the clutch dog, maintaining the existing gears. Of course, I will visually inspect the gears for any damage, either to the teeth, or the mating surface to the clutch dog.

If it turns out to be necessary to replace the pinion and fwd gears, any suggestions for shim tool substitute? Or should I bite the bullet and purchase the recommended tools?

Next: the service manual gearcase dissasembly procedure indicates special tools required to remove the pinon bearing. However, the clutch dog, pinion and fwd gears are already removed by this step. Assuming the pinon bearing is re-usable, I assume I would not need to remove it, eliminating need for the tool (or substitute). When removing the LU, I'll check to see if there is any excessive driveshaft play to determine "re-usability". I did change the water pump earlier this season and did not notice any loose fit. Seem reasonable?

Similarly for the driveshaft bearings in the the bearing housing: I'll check for prop shaft play - assuming this is not excessive, I'll plan to re-use the original bearings.


Summarizing:
- pending visual inspection, OK to re-use the existing pinion and fwd gear?
- pending inspection of driveshaft play: do not remove pinon bearing (eliminate special tool reqt)
- pending inspection of prop shaft play: do not remove fwd/aft bearings from housing (elim special tool)

This information will be useful for me to scope out the job, and necessary tools.

After this, I'll have some additional questions regarding other special tools...

thanks,

Paul

 

[Tim Frank]

In my experience, but you'd be better with one of the gurus weighing in, unless there has been some serious "stuff" going on in the gear case, those two gears are very robust, it takes a lot to damage them. A good inspection should show you their condition reliably.
The clutch dog is the wear-item....and your experience is consistent with wear.
Unless $$$ are no concern, I'd just change what you find to be worn, and reseal the unit.