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Matchless 1959 250 G2 Oil pump problem
#759889 12/20/18 4:58 pm
Joined: Jan 2014
Posts: 1
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I am currently working on a 1959 Matchless 250 G2 motor, The oil pump shaft has teeth missing from the worm gear that runs on the crank shaft spline gear, I cant fine a way to remove it although I have taken out the retaining cross bolts. I notice that there are some brass pins driven into the aluminium casting, but I cant see them needing removal, i have tried heating the crank case an gently tapping the shaft to no movement, there also does not seem to be any way of gripping the shaft, to pull it out
Regards Len Harrison Cape Town

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Re: Matchless 1959 250 G2 Oil pump problem
Len Harrison #759917 12/20/18 9:12 pm
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I think these have the same reciprocating/ rotating oil pump as on the Heavyweights that I'm more familiar with. At the rear of the oil pump housing, facing downwards, is a hex head of the guide screw. Remove this, and push the pump rearwards from the forward end. Gently turning the engine backwards assists in this .On the Heavyweights, this forward plate also has fitting for the overhead gear feed pipe to be attached. Obviously, this needs to be detached to remove front plate.

Re: Matchless 1959 250 G2 Oil pump problem
Len Harrison #759950 12/21/18 1:59 am
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Yes,it's broadly the same as the heavyweight singles. The instruction book is very keen on telling you that, If for any reason, the crankcase is dismantled, the oil pump plunger must be removed from it's housing before attempting to separate the crankcase halves. It is also necessary to remove the small timing pinion. This instruction is in italics for emphasis so one can assume Matchless were quite familiar with the sort of mess you describe.
As with all these pumps you have to remove the guide screw before sliding the oil pump out and also remember the guide screw is hollow and contains the actual pin that engages with the cam slot in the pump. Unlike the heavyweight singles where the guide screw is on an angle so retains the pin on removal (gravity is marvellous) the G2 guide screw is horizontal so there is a faint possibility the pin may remain behind (Murphy's Law). From your description the pin may still be in there and who knows what internal damage has been done to date before you took the job on.
Sorry to sound a bit grumpy but at the moment I am contemplating a crankcase where a PO has done some really inelegant "repairs" and I haven't yet figured out how to retrieve the mess. Usually misery loves company so hearing of someone else in the same boat would be soothing but knowing the Mk 1 F***wit is still out there wrecking engines is reducing my Xmas spirit somewhat.


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