1968 selectroshift 40hp

[gusthewonderslug]

Hi all I have just rebuilt my gear case,new bearings new seals,I have taken the boat out for a run and all good, then took my kids surfing behind the boat and noted that the engine is roaring! It sounds as though the pinion gears in the gearcase are meshing to deeply.
I don't have any excessive end float in the drive shaft and it only makes the noise when under load, to be fair I'm running ATF in the gear case as the dealer had none of the correct oil in stock.
Could this be causing the noise I am experiencing.
I would like to hear from anyone with their ideas before i strip the gear case down again.
Gus

 

[F_R]

Re: 1968 selectroshift 40hp

I don't think the oil would make it noisy. You mention no excessive end float in the drive shaft. I'm wondering just how you determined that. The "drive" shaft is the vertical shaft--is that what you mean? It must have end float so it doesn't mash down on the pinion.

No whine or unusual noises at idle? That's kind of odd.

I don't know what's wrong.

 

[gusthewonderslug]

Re: 1968 selectroshift 40hp

I don't think the oil would make it noisy. You mention no excessive end float in the drive shaft. I'm wondering just how you determined that. The "drive" shaft is the vertical shaft--is that what you mean? It must have end float so it doesn't mash down on the pinion.

No whine or unusual noises at idle? That's kind of odd.

I don't know what's wrong.

Sorry output shaft propshaft

 

[jimmbo]

Re: 1968 selectroshift 40hp

Why in the world would you put ATF in it in the first place? "dealer had none of the correct oil in stock" is not an acceptable answer. From what I remember in the qwners and service manuals was Type C(now Premium Blend) only.

 

[F_R]

Re: 1968 selectroshift 40hp

Yeah, I figured that was what you meant. There really isn't that much to go wrong in there, as far as gear mesh is concerned. The forward gear and clutch hub thrusts against the tapered roller bearing in the nose of the gearcase. Did you have that bearing race removed? If you did, you may not have gotten it completely seated in the case.

The pinion gear thrusts against the flat roller bearings above the big roller bearing. Did you have those out? If you did, did you notice the two races are different size? The smaller one goes down, against the pinion.

Other than that, I don't know what you did wrong. You describe it as a "roar". A "roar" description makes me think exhaust noise. Are you sure it is gear noise? By chance, is the heat tube between the exhaust manifold and carburetor missing or broken? Just guessing now.

 

[gusthewonderslug]

Re: 1968 selectroshift 40hp

Guys thanks for the replies, yes it got me stumped as well.
My first thought was I had forgotten one of the thrust washers on the output shaft, but as I don't have excessive end float, I'm confident that all is good.
Jimmbo here in West Aust we don't have outboard dealers on every corner and from what I'm led to believe I'm the only owner with a running Electroshift in the state, so it hardly worth the dealer in my area stocking oil, from the MSDS on the Type C "ATF" is a fair substitute. so I used what was available.
For those willing to offer sound advice rather than cast manure, here is what I've done so far, I have now run the motor in a tank with the prop removed and cant hear the noise but there is also no load with no prop, I have also pulled the plugs put it in gear and turned it over from the prop, I can feel a definite restriction "ropeyness" but this could be normal as I'm potentially turning the engine over backward and the gear engagement and preload will be wrong as the drive should come from the motor not the prop.
Before I strip it down I will source some Type C refill and take it for a run, failing that fixing the issue, it looks like another tear down.
I didn't have any extras left over after the rebuild so my only concern is that I have installed the two flat rollers in the wrong sequence.
Im pretty sure I didn't as I matched them to the polished faces on the spacer that runs between them.
F-R can you please describe what you mean by the heat tube, I had a ***** of a time getting the water tubes to line up with the water pump housing when reassembling.
I have one last "very silly" question if the fuel to oil mix was "way way" rich would this make the motor sound different.
As a last ditch fact finding mission before I tear it down "I asked my son how much oil he used in the fuel and his answer was 1/2 a bottle so it was running a 20-1 mix could this make a distinct difference in the sound of the engine?

Thanks again for every ones assistance.

Gus

 

[racerone]

Re: 1968 selectroshift 40hp

The heat tube feeds air to the automatic choke.--------Cold air on start-up and warm air when engine heats up.---On starboard side of the motor block.

 

[gusthewonderslug]

Re: 1968 selectroshift 40hp

Racerone

Many thanks for the explanation.

Gus