Help/Advice on Oil Plunger

[MrGoose2U]

Good afternoon all,

Hoping that you guys will save me some time with an issue.

After fixing the funning issues with a new carb, I discovered that the Oil flow was not happening.

Using the advice given on "Houston we have a problem" and others I started to check all parts of the il system. New Oil filter was still totally dry.

Removed Rank and tried to blow the pipes through (nothing). So removed the Plunger and screws and managed to clear the Pipes (yay) with a lot of force.

That is when I noticed that the Plunger has some damage to the Cog fins. (2 broken off).

So my questions are:

• What is the chance something else is damaged?

• What does this connect to, so I can check it?

• What is the part(s) that I may need to replace, so that I can get this fixed ASAP?

Kind regards

Gareth

[Steve]

OUCH and the shaft looks completely unmarked apart from the damage, gutted for you.

[Steve]

Just looked and it's driven from the timing side crankshaft, fingers crossed for you that the crankshaft is still OK.

[Joker_Bones]

The plunger is driven by the worm drive on the timing side axle.

IMG_20230723_150716.jpg

[Joker_Bones]

Your plunger appears brand new. Recently replaced?
The plunger and worm drive have changed over the years. They are not necessarily interchangeable. If the wrong plunger was fitted I imagine the result could look like what you have.

[MrGoose2U]

Ok thanks guys.

So I am going to take a rough guess that this is not a quick cover off type check....

Bugger.

I do not know if it was recently changed as I have just bought the bike.

[MrGoose2U]

So it is this item that I am potentially looking at?

https://www.amoc-parts.com//store/comer ... duct=20852

Just ordered a new plunger from AMOC spares so assume that if I buy both from them it will be the right fit.

[Joker_Bones]

Assuming your engine is pre 1947 and assuming it has the pre 47 flywheels and axle then the worm drive should be a single start.
Later engines have a two start worm drive, compare the pictures on amoc spares.
If you look up the bore the plunger fits into you can just see the worm drive. If you can see in enough detail to see if it is damaged or not... I don't know.
Is the plunger bore okay?
Two start plungers may be stamped 2S... I don't know if new ones are, is yours stamped?

IMG_20230818_170751.jpg

IMG_20230818_170920.jpg

[Joker_Bones]

viewtopic.php?t=30101

This thread shows a plunger with similar damage to yours... Caused by a new guide pin that was too long.

[SPRIDDLER]

Your 1941 G3L should have the single start axle worm drive and single start plunger.

Removed Rank and tried to blow the pipes through (nothing). So removed the Plunger and screws and managed to clear the Pipes (yay) with a lot of force.

What came out when you cleared the blockage - steel bits/swarf from the plunger splines?
Which 'pipes' did you clear? The feed and return from the oil tank? I'd drain the oil tank and crankcase and check the oil and the filter for shiny bits and glittery steel dust.

• What is the chance something else is damaged?

Quite high since the bits of broken plunger spline must have gone somewhere (unless an already broken plunger was fitted by the PO).
In addition the worm drive on the axle may be damaged.
Not to mention the steel swarf getting into the big end, timing side axle bush, main ball bearings and elsewhere.
Does the plunger have 2S stamped on one end?