88 johnson 60 hp

outlawjj

Recruit
Joined
Oct 7, 2011
Messages
4
when running wot feels like hit something see motor jump. no metal in lower unit. changed out coils, power pack,spark plugs. 1/2 throttle no problem.
 

retiredfornow

Petty Officer 1st Class
Joined
May 9, 2011
Messages
355
Re: 88 johnson 60 hp

It might be seizing. What did the plugs look like? What's the compression?
 

outlawjj

Recruit
Joined
Oct 7, 2011
Messages
4
Re: 88 johnson 60 hp

have not ckd compression motor starts good runs good idles good plugs looked good
only problem is the one i mentioned
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: 88 johnson 60 hp

(Jumping Out Of Gear - Manual Type)
(J. Reeves)

This pertains to lower units on all OMC manual shift outboard engines, or any OMC engine with lower units defined as a Shift Assist or a Hydro Electric Shift unit which incorporates a "Shifter Clutch Dog".

Within the lower unit, splined to the prop shaft is what is most often referred to as a clutch dog, hereafter simply called dog. The dog has at least two lobes protruding from it on both ends, facing both forward and reverse gear. The forward and reverse gears also have lobes built into them near their center area. When the engine is running, in neutral, the gears are spinning constantly via the driveshaft being connected directly to the powerhead crankshaft, but the propeller does not turn due to the fact that the dog is centered between the two gears, and the dog lobes are not touching either of the gear lobes.

When the unit is put into either gear, shift linkages force the dog (and its lobes of course) to engage the lobes of the gear. The lobes of the spinning gear grab the lobes of the dog, and since the dog is splined to the prop shaft, the propeller turns.

The lobes of the dog and gears are precisely machined, most with right angled edges that could be installed in either direction, and some with angles slightly varied that must be installed in one direction only (one end only must face the propeller). Dogs that can be installed in one direction only, if reversed, even if the dog and both gears were new.... would jump out of gear almost immediately. Keep in mind that the lobes are precisely machined with sharp angles!

Due to improper adjustment or worn shift linkages, but usually due to improper slow shifting, those precisely machined sharp edges of the lobes become slightly rounded. Now, with those lobes rounded, as the rpms increase, the pressure of the gear lobes upon the dog lobes increases to a point whereas they are forced apart (jumping out of gear), and due (usually) to the shift cable keeping tension on the engines shift linkages..... the unit is forced back into gear giving one the sensation that the engine has hit something, and the cycle continues.

Some boaters with manual shift engines have the mistaken belief that shifting slowly is taking it easy on all of the shifting components..... Wrong! Shifting slowly allows those precisely machined sharp edges of the dog and gears to click, clank, bang, slam against each other many times before they are finally forced into alignment with each other..... and this is what rounds those edges off! The proper way to shift is to snap the unit into gear as quickly as possible.
 

lmuss53

Lieutenant Junior Grade
Joined
Sep 9, 2008
Messages
1,227
Re: 88 johnson 60 hp

I let someone adjust the linkage on my 90 last year and it started doing this. I popped the cap off and moved the shift linkage about 2 turns in the direction to engage forward a little more and the clunking stopped. An adjustment like that might help your issue if the dog is not too far gone.
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: 88 johnson 60 hp

Imuss53 makes a good point..... adding to it here:

(Centering Shift Cable)
(J. Reeves)

When all is as it should be, the proper method to adjust the shift cable is to disconnect the cable from the engine. Move the shift linkage on the engine to find the center of the play in neutral, and when found, leave it centered.

Now, grab the end of the shift cable sleeve, push and pull it to find the center of the play there, and center that play.

Adjust the trunion on the threaded portion of the shift cable so that the centered play of the cable lines up with the centered play of the engine's shift linkage. Install and lock the shift cable with the retaining clamp in that position. That's it.
 

outlawjj

Recruit
Joined
Oct 7, 2011
Messages
4
Re: 88 johnson 60 hp

Thanks for the input Imuss53, Joe, and retiredfornow.
Going to the lake tomorrow to try the adjustment on the cable.
I will report back
 

outlawjj

Recruit
Joined
Oct 7, 2011
Messages
4
Re: 88 johnson 60 hp

Just got back from the lake. Three adjustments and nine turns and no more clunking for now.
thanks again for the info
 
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