Starter motor shaft - plastic sleeve?

[Tim Good]

I’m just swapping out my starter motor on a Perkins 4.236.

I’ve removed the old one and just ahead of the drive pinion (gear) is a plastic sleeve surrounding the spring.

On my new (reconditioned) motor there is no plastic sleeve. I’m just curious what it is and if it is worth my removing it from the old one and placing it on the new?

Old and new pics below:

 

[Spirit (of Glenans)]

I think it's meant to retain grease.

 

[Tim Good]

I think it's meant to retain grease.

I thought the pinion and shaft are lubricated by the engine oil?

 

[Momac]

There should be no engine oil involved unless there is an oil leak

 

[Hunterlees]

On your old starter- how can the pinion gear move horizontally along the bendix? it seems that the sleeve has been added to prevent that. In which case there is a difference between old and new starters.

 

[Tim Good]

On your old starter- how can the pinion gear move horizontally along the bendix? it seems that the sleeve has been added to prevent that. In which case there is a difference between old and new starters.

Good question. They’re deffo the identical model so I just checked: It seems to just slide up and over the nut on the end.

 

[William_H]

If the plastic sleeve slides over the nut when the spring is compressed what would make it return to cover the spring? yes it might retain grease to a degree perhaps. I think I would leave it out. ol'will

 

[penfold]

It appears to be retained against the pinion by the spring; I imagine it is shaped like a plastic beaker with a large hole in the bottom. Quite a conscientious piece of detail design, I would retain it as it allows the helix to be greased with much reduced risk of the grease attracting dirt and causing subsequent binding, unshielded bendix gears should only be lubricated with graphite or other dry lubricant for this reason. On a boat the salt and damp atmosphere plus infrequent use mean surface rusting is a much greater hazard to reliable operation, grease offers much greater protection than graphite.

 

[Boater Sam]

The maker didn't waste money adding unnecessary parts, they considered it worth spending money on a part so use it.

 

[Refueler]

There's an old seamans saying :

If it moves : Oil it
If it moves occasionally : Grease it
If it does not move : Paint it

Personally I'd leave that plastic off .... I have a Perkins 4-107 - with similar starter ... no plastic at all ...