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Needle bearings in manual starter

T

tomf

Regular Contributor
"Well, here's some real es

"Well, here's some real esoterica for those in the know. In the midst of cleaning up my project 15hp Mariner (1990 model), I noticed this:

294207.jpg
Mariner 15hp starter bearings"">

That is to say, one of the needle bearings in the recoil starter sheave hub seems to be missing. The picture sucks but you can see the empty space to the right of the 3 bearings.

I presume this is a bug and not a feature. But is it, and if so, is there anything I can do to fix it short of replacing the whole starter? The sheave seems to rotate ok on the flywheel nut stub shaft, but I'm not really happy about missing a needle bearing in a part that's under continuous high-RPM rotation.

By the way, while we're on the topic, can someone explain the mechanism by which the starter only rotates one way on the stub shaft? Haven't been able to figure this one out.
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Or does it have something to do with this "missing" bearing?"
 
"Thank you, yes I believe this

"Thank you, yes I believe this is exactly what we're talking about.

Now if I can only figure out whether the gap in the bearings (sprags?) is normal or not... unfortunately my other 15hp has a slightly different starter design so I can't just pop that one off and see what it looks like.

If anyone happens to have one these early 1990s starter units lying around and can have a look, that would be most helpful.

The freewheel mechanism works fine when horizontal - tilted to the side 90° it occasionally seems to hang a bit but I don't know if this is an issue. Probably not good if it does that at 5900 rpm though..."
 
"From the pic, it looks like t

"From the pic, it looks like the bearing cage is divided. Is there an equal number of bearings in each section?"
 
"Yes, there are 4 bearings in

"Yes, there are 4 bearings in each section of the cage - except for the one in question which only has 3. So to me it looks pretty obvious that something is missing, unless the design is intentional and part of some really weird clutch mechanism.

The whole starter assy. is in pretty funky shape so I wouldn't be surprised if a bearing had been misplaced sometime in the motor's lifetime (the starter has clearly been off, and there are other small parts missing/broken as well). Depending on how this bearing thing works out, I'll probably decide between trying to restore the starter or just try to pick up a replacement unit at the local salvage shop..."
 
"OK, got a closer look at the

"OK, got a closer look at the part and things are starting to make more sense now. The red "bearing" cage is in fact the sprag/one-way bearing assembly, and the smaller races on top and bottom are the actual roller bearings.

So the missing part is not an ordinary needle bearing but one of the sprag cams - obviously not something you can just pop in and replace easily.

Looks like a simple question of replacing the whole unit, then, or taking a chance on the clutch possibly seizing at some inopportune time in the future. Somehow leaning towards the former.

On a philosophical side note, a nice little example of how you don't see things unless you know what you're seeing.
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"
 
And one doesn't learn thin

And one doesn't learn things without getting one's hands dirty. Thanks! I didn't know starters were made like that. Neat design.

Jeff
 
"Yeah, probably expensive to b

"Yeah, probably expensive to build too. On slightly later models in the same series they seem to have switched to a slightly different design with an angular cam that grabs the flywheel, instead of this one-way clutch bearing. Or maybe the newer version was just simpler to manufacture or more reliable, I don't know.

Design II:


Mariner 15hp manual starter, Design II
 
"I presume you mean the versio

"I presume you mean the version with the sprag-style clutch in my original post? The parts diagram ("Design I") looks like this (compare with the above):

http://www.marineengine.com/discus/messages/12479/294298.png"" alt=""Merc/Mariner 15hp starter, design 1"">

The one-way bearing is in the middle of part #19, and drives the crankshaft via a short stub shaft that is actually part of the flywheel nut, part 1 here:

[img]http://www.marineengine.com/discus/messages/12479/294299.png"" alt=""Merc/Mariner 15 flywheel assy."">

Here's a pic of the full starter from below:

[img]http://www.marineengine.com/discus/messages/12479/294300.jpgMerc/Mariner 15hp starter from below, design 1 "">

Hope this helps!

Tom"
 
"Slick! Thanks. I have a cou

"Slick! Thanks. I have a couple of the 'normal' starters for a Merc 25 and they look similar.

Jeff

PS: You wouldn't have a mid-80s stator for a Merc 25 laying about, would you?"
 
"No, sorry... so far my experi

"No, sorry... so far my experience (and miscellaneous parts stock) is limited to a couple of 15hp's and some Johnson/Evinrude Fours.
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"
 
"Jeff, this wouldn't by an

"Jeff, this wouldn't by any chance be the stator you're looking for? It's from a 20hp blue-stripe, so probably too old?

294785.jpg
Mercury 20 hp stator
 
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