1978 evinrude has a hard "jerk" every 26 seconds

[oldboat1]

Re: 1978 evinrude has a hard "jerk" every 26 seconds

On behalf of us shadetree mechanics, the forward gear is on the transom side of the gearcase, and the reverse gear on the prop end, right? (Say, if one wanted to inspect for forward gear/shiftdog damage). That would be for a clockwise spinning driveshaft, and a right hand prop. Small motors with no gearshift would have a prop-end (“reverse”) gear only, using a counter clockwise/left hand prop to move the boat forward. Correct?

 

[daselbee]

Re: 1978 evinrude has a hard "jerk" every 26 seconds

Hiya oldboat...

First part of your question....yes the forward gear is on the transom side of the gearcase, up in the nose. Problem is, to inspect, you have to pretty much disassemble the whole gearcase. It is a big job.
I think, emphasize THINK, that on an Evinrude V6 case you have to remove the pinion nut, pinion gear, and driveshaft just to be able to see in there to the forward gear. That takes a special pinion nut holder tool and a way to turn the driveshaft to break the pinion nut loose.
Putting it back is even more involved.

On a Suzuki 70 hp, you can remove the bearing carrier, and propshaft with the clutch dog as one unit, enabling close inspection of the forward side dog cogs. As was noted above, there ARE differences....

Regarding the smaller motors, I don't know.

 

[oldboat1]

Re: 1978 evinrude has a hard "jerk" every 26 seconds

backatcha, daselbee. Thanks for the info. Special tool required is usually the magic phrase -- can handle some of the older and simpler/smaller, and sticking with that. OP is an auto mechanic, and can probably take on the gearcase.

 

[Bob_VT]

Re: 1978 evinrude has a hard "jerk" every 26 seconds

Okay I will yield to the Joe Reeves explanation and just watch

 

[theoldbaboon]

Re: 1978 evinrude has a hard "jerk" every 26 seconds

Ok...I did my due diligence....I checked spark with a timing light...perfect on all cylinders. I took the lower unit apart, the "square cogs" are not sharp on the edges at all, neither side, so Iit's a good bet that they've been reversed already. I also noticed that the surface face of the cogs have "track" marks showing they've slid across the face of each other. Thanks to all who gave input on my situation! It's greatly appreciated!!! I have a spare lower unit that didn't have this issue so I'm stealing the dog and gears from it. I did find a magnet in the shift rod cavity with a spring wrapped around it....is this just a shaving collector magnet???? Not sure where it's supposed to be. Once it's all together, I'll test it out and post the results. Thanks again everyone!!!!

 

[theoldbaboon]

Re: 1978 evinrude has a hard "jerk" every 26 seconds

Yep... just before that jerking tears your transom off.

Trust us my friend and don't question what we have experienced for 30 or 40 years. You have a clutch dog/forward gear problem which will require dismantling the lower unit. Best to have a Service Manual that is specificly for that individual engine... not a manual that covers a half dozen or so that will greatly confuse you.

You might try the following cable centering, but if that does you no good, resolve yourself to a lower unit repair job.

(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.

Thanks for the heads up on centering the shift cable!!! Awesome info!!!

 

[Joe Reeves]

Re: 1978 evinrude has a hard "jerk" every 26 seconds

Check closely the shifter dog as most cannot be reversed. Look for a imprint on the dog that states "Prop End".

 

[racerone]

Re: 1978 evinrude has a hard "jerk" every 26 seconds

The magnet is for collecting the fine steel parts due to normal wear.------The clutch dog can only be installed one way !

 

[theoldbaboon]

Re: 1978 evinrude has a hard "jerk" every 26 seconds

I replaced only the shifter dog after contemplating changing the forward gear as well. After closely comparing two sets of gears and two sets of shifter clutch dogs, i came to the conclusion that the shifter clutch dogs were the problem. I took her out today and ran a half of tank of gas out at full throttle and not once did it Jerk, bang, whine or anything....she ran GREAT!!!! thanks again to everyone out there who had input!!! I couldn't have done this without the help!!!!

 

[Joe Reeves]

Re: 1978 evinrude has a hard "jerk" every 26 seconds

Every once in awhile... someone listens to us.

 

[daselbee]

Re: 1978 evinrude has a hard "jerk" every 26 seconds

Every once in awhile... someone listens to us.

Heard that.....how right you are.....