10hp evinrude 1962 engine help! (drive shaft)

[wing nut]

hey guys,

i not this isnt exactly "speed boats" but i have a 1962 evinrude that has ran great for a long time (i got the engine from a friend). but now the drive shaft seems to be "loose"

this is the weird part and i cant figure it out.. with the impeller on and the engine togerther the engine sorta "Jumps" like the drive shaft goes up and the engine stops turning the prop, then it drops back down and it jolts the engine/boat.

with the impeller off and the engine apart i can slide the engine up about 1inch with it still turning the prop. then i can slide it up about another 4-6 inches and by then the drive shaft isnt turning the prop at all.

does anyone know what could cause this??


thanx
scott

[Backfire]

gottagofast227
From your description of a problem, I assume you don't have a clue of what is the problem might be. From what you say "jolts the engine", I guess the problem to be the shift dog/clutch. Nothing to do with the drive shaft. The engine is jumping out of gear under power-then right back into gear. The cause of this is that the forward gear has the clutch contact point worn off the gear and dog to the point it will no longer stay in gear under strain. The only joint in the drive train is the splines in the bottom of the crankshaft and matching splines on the top of the driveshaft, and the splines on the lower end of the driveshaft and the matching splines in the pinion gear. If you have had the lower unit off and looked at the upper driveshaft splines and they look normal, remove the water pump impeller, pull the driveshaft out of the gearcase and look at the splines on that end. If normal then you can assume the gear/clutch need replacement. There is some adjustments that can be made by you reading a service manual or somebody that is familiar with that model. If you plan on running this engine into the future, I would replace ALL seals/
o-rings-driveshaft, propshaft, and shift shaft. There is some linkage under the powerhead that could be a problem also. On that age, anything is possible. If you pull the powerhead for any reason, be sure and change the "quad seal" on the bottom of the crank. Get a manual from your local dealer. Good Luck!
Backfire '63 18hp Johnson

[Flat Out]

Backfire is right on. The clutch dog is most likely worn. The old 10s and 18s will do this after a zillion hours. It's easy to fix and the motor will run another hundred years. The split gearcase makes repairs easy. Adjustment once repaired is not difficult. Sometimes you can cheat by flipping the clutch dog around if it's not too worn. I have a pile of 10s and 18s so I can help you if you need some assistance. These are some of the best motors ever made ( I feel). Not the most glamourous but real workhorses. As long as you have oil in the gas you can't kill them,These motors are 30,40 and some close to 50 years old and people are still using them.

[woodco]

I had an old early 60's 18 hp on a lil 8 ft hydro. Spent many hours
replacin the clutch dog and gears.That was the only problem I ever had with it ..... except water problems ....... Had the hydro
upside down as much as right side up !!!!