1964 Evinrude 75hp, bangs while in gear

[Evinrude Boater]

My motor bangs occasionally while at low speed and now I'm feeling it when accelerating. It's like it's hitting a rock. I'm thinking the clutch dog is slipping or disegaging momentarily. Once on plane it doesn't do it even when varying the speed. This is the wrong time of year for lower end disassembly but would you agree the clutch dog and gears need inspection. If ignored could this cause rapid deterioration or damage?

 

[R.Johnson]

Re: 1964 Evinrude 75hp, bangs while in gear

You will find you already have damage, is this a manual, or selectric shift?

 

[Evinrude Boater]

Re: 1964 Evinrude 75hp, bangs while in gear

Manual shift, it's the one in my avatar. What sort of "damage"? Do you think I should be pulling it out of the water now and open it up?

 

[CATransplant]

Re: 1964 Evinrude 75hp, bangs while in gear

You can check the adjustment of the cable to make sure it is allowing the shifter to move fully into the forward position, but it's more likely that the clutch dog in the lower unit is worn. You have the classic symptoms of that.

If so, it will not get better. It will just get worse, and fairly quickly, once it starts jumping out of gear like that.

The only fix is to get in there and replace the worn parts.

 

[F_R]

Re: 1964 Evinrude 75hp, bangs while in gear

Evinrude, it certainly sounds like it is a clutch dog, except for one little detail. You say it does it at low speed and not high speed. That is 100% opposite from the norm. Something fishy here.

 

[HighTrim]

Re: 1964 Evinrude 75hp, bangs while in gear

Evinrude, it certainly sounds like it is a clutch dog, except for one little detail. You say it does it at low speed and not high speed. That is 100% opposite from the norm. Something fishy here.

Exactly my thoughts while reading through this. Normally it is the higher RPMS that force the machined edges of the dog and gear apart. Have you checked the condition of the lu lube lately?

 

[Evinrude Boater]

Re: 1964 Evinrude 75hp, bangs while in gear

It happens when idling out from my dock and I didn't give it much thought. Actually I thought it was the engine missing like a lean sneeze then it happened twice while pulling the tube. I didn't push the throttle to WOT but just accelerated and it would bump or bang once on the way up to plane. It doesn't rev up like it would if it slipped out of gear. If it comes out of gear do you have to throttle back and start again?
I change the lube every season but I haven't checked it since this year. What are you thinking? Low? Milky? After tubing three kids this afternoon I pulled the engine up and felt the gear case. It was cool but I did idle in to dock and maybe it cooled on the way in.

 

[HighTrim]

Re: 1964 Evinrude 75hp, bangs while in gear

Wondering if it was possibly low, OR any abnormally sized shavings present larger than peach fuzz.

Let us know what you find, is interesting.

 

[R.Johnson]

Re: 1964 Evinrude 75hp, bangs while in gear

You can't pull an aluminum gearcase out of the water, and exspect it to be warm to the touch.

 

[kjdunne]

Re: 1964 Evinrude 75hp, bangs while in gear

The gearcase will not completly disengage from gear and allow the engine to rev up freely from a worn clutch dog. I agree that it sounds unusual that this happens at low speeds but not high speed. You say it is beginning to occur during acceleration, so it leads toward the worn clutch dog/gear. Continued use will not help matters, they don't heal themselves. Time to check it out.

 

[Evinrude Boater]

Re: 1964 Evinrude 75hp, bangs while in gear

You can't pull an aluminum gearcase out of the water, and exspect it to be warm to the touch.

It has been warm in the past. I thought it was just the exhaust gases warming up the lower end.

 

[Evinrude Boater]

Re: 1964 Evinrude 75hp, bangs while in gear

Will an electric shift lower end bolt up to mine? I realize I'll need the matching control box and wiring.

 

[F_R]

Re: 1964 Evinrude 75hp, bangs while in gear

Yes it will. You will need the special cover plate for the exhaust housing where the shift rod disconnect cover is now. The electric wire goes through it.

 

[Evinrude Boater]

Re: 1964 Evinrude 75hp, bangs while in gear

Yes it will. You will need the special cover plate for the exhaust housing where the shift rod disconnect cover is now. The electric wire goes through it.

If I get an electric shift lower end, I'll get the whole motor so it should be there. I hope they're the same shape.

I see the mechanical shift gears are $400 and the electric gears are $125. What's the difference there?

Is there any way to test an electric shift without running the motor? Should it be in neutral or in gear when no power is connected?

 

[Evinrude Boater]

Re: 1964 Evinrude 75hp, bangs while in gear

I did the link & sync again since I think I left out a step 3 years ago. It idled better and I also noticed play in the throttle cable so it wouldn't pull the throttle back all the way. After I adjust the cable it slides into gear so quietly and accelerates better and I think it goes faster now. No sign of the low speed bang either. I wonder if the engine was missing and these adjustments have corrected that.
It's also nice to be able to dock without plowing through it.