25hp Evinrude jolts violently

[imported_Zoso]

Just bought the boat and motor used. Believe it to be a 72. Third time i had the boat in the water it would jolt heavily every 60 seconds or so as if i had hit a stump. That's what I thought had happened at first. It only does it when in gear and like I said, it's kinda like I hit a stump or something every time it happens. Motor starts and runs great. Please advise, thank You!

 

[Scaaty]

Re: 25hp Evinrude jolts violently

Jumping out of gear maybe?

 

[imported_Zoso]

Re: 25hp Evinrude jolts violently

That's what a friend of mine recomended but the boat does remain in gear throughout.

 

[ezeke]

Re: 25hp Evinrude jolts violently

Sounds like the hub might be spun on your prop. Make a waterproof line across the face of the propeller hub and the propeller shaft and see if it stays aligned after an incident.

Props for your motor have both a shear pin and a rubber grommet between the inner and outer sections of the propeller hub. The shear pin may be broken, but it sounds more like the rubber seal has gone.

 

[steelespike]

Re: 25hp Evinrude jolts violently

Sure sounds like a worn clutch dog.Classic symtom and fairly common problem.Considered a normal wear item.Relatively easy repair for the mechanically inclined.There are also detent balls in the clutch assembly that help to keep it in gear.After repair you can prolong the life by being sure the engine idles nice and low shift only at low idle.Shift crisply neither dragging it into gear nor jamming it into gear.

 

[BoatBuoy]

Re: 25hp Evinrude jolts violently

If it's a remote control, disconnect the shift cable from moter, shift into forward and see if it still does it.

If it still does it and you don't have a spun prop, you got a bad clutch dog, dude.

The nubs that the clutch dog engages on the gear may also be worn.

 

[imported_Zoso]

Re: 25hp Evinrude jolts violently

Thank you for the advice. I took the prop off today and the pin looks fine, although I did not see a rubber seal. I would like to check out the clutch dog but I have to be honest with you, I have no idea where to look or what it looks like, or even what it does. What do I need to remove to look for this problem, is there any other way to know?

 

[ezeke]

Re: 25hp Evinrude jolts violently

You will not see the rubber seal because it is between the two parts of the propeller's hub. You can try marking the prop, hub and shaft or try another prop.

If you go to the Parts diagrams and look up your motor and then navigate to your gearcase, you will be able to see the components of the gearcase and their respective names:

http://epc.brp.com/default.aspx?brands=ej&lang=e

There are three gears in the gearcase; two on the propshaft and one on the driveshaft. The one on the driveshaft keeps the two on the propshaft in constant motion whenever the engine is running. Because the two gears on the propshaft are on either side of the driveshaft gear, the two propshaft gears are turning in opposite directions at all times.

The dog runs back and forth between the two propshaft gears, directed by your shift lever. When the dog engages one of the gears the propshaft turns with it. If it is not engaged you are in neutral.

 

[steelespike]

Re: 25hp Evinrude jolts violently

You really should start by getting a service manual.
The the clutch dog is in the gearcase just remove the bottom and look in.The dog is splined on the prop shaft and slides between the forward and reverse gears.to engage them with the shaft.

 

[imported_Zoso]

Re: 25hp Evinrude jolts violently

I will certainly take a look at that. Is opening up my lower unit going to require me to replace any seals/gaskets? That way I could be prepared to put it all back together. Also, I saw on another site that you could possibly turn the clutch dog around so that the worn side will be on the reverse gear side. Any truth to that. I could not locate the part I need on this site.

 

[ezeke]

Re: 25hp Evinrude jolts violently

You can turn the clutch dog around. You will need a seal kit, and a hand impact tool will help to remove the screws from the case.

http://www.iboats.com/mall/partfind...row=18&keywords=seal kit&session_id=914533676

You will also need a new supply of high viscosity gear oil.

 

[F_R]

Re: 25hp Evinrude jolts violently

You might get lucky. However in many, if not most, cases, the forward gear is also worn because they bang together equally. If that is true here, replacing just the dog, or turning it around is just wishful thinking. It might even work for a couple of weeks. Jumping every 60 seconds, you have serious wear down there and it gets worse with every bang. Keep it up and you will also wear out the linkages

 

[imported_Zoso]

Re: 25hp Evinrude jolts violently

Thanks for the link to the seal kit. I will definitly check it out

 

[ezeke]

Re: 25hp Evinrude jolts violently

Are you sure that the shift rod connector is hooked up correctly?

 

[perkdp]

Re: 25hp Evinrude jolts violently

If the prop is spun from the rubber hub you'd most likely get a high rev when the prop slips. Generally, once it begins to slip, it won't grab again until you release the throttle to reduce the load. And will usually, if it don't slipp all the time, will only slip at take off (heavier load) or during a hard turn.

Sounds to me like you have a worn clutch dog.