oil pumps

[KiwiGF]

Thank you Bsareg!  I found the CPC brackets online.  They are a brilliant design, and at a reasonable cost.

This almost makes up for the some of the recent setbacks on my project, such as discovering that the original oil pump is completely seized...

It’s not uncommon to find seized pumps if made in mazak, they are fixable at zero cost in most cases given time and patience. It’s good practice to check these pumps rotate freely before running a bike been left standing a while, they might work for a while then strip the gears driving them with horrible results.

[Swarfcut]

 Good advice there from Kiwi. Always use caution with a barnfind bike and don't just jump on the kicker. Seized pumps can be dismantled by heating up with a hot air gun or in the oven when SWMBO is away.  The gears and shaft can usually be tapped from the body. Bloated and cracked bodies should be rejected, but if it looks reasonable, well worth playing with. Plenty on the Forum already about the finer aspects of pumps.

 Swarfy.

[tomkilde]

Thanks Swarfy.  The pump spins freely if I loosen the four screws on the end plate, but seizes up firmly when I tighten them again.  I've read the threads on how to fix it, but replacement seems the safer bet.  I will be ordering a new SRM oil pump as soon as I recover from the shock of the price.

[Rex]

Is the little separate fibre washer in place at the nose of the pump?
Always makes me cringe when I see posts on F-B where someone's showing off his latest barn find, and someone else suggests he "pours in some juice and give it a kick".

[KiwiGF]

Thanks Swarfy.  The pump spins freely if I loosen the four screws on the end plate, but seizes up firmly when I tighten them again.  I've read the threads on how to fix it, but replacement seems the safer bet.  I will be ordering a new SRM oil pump as soon as I recover from the shock of the price.

On a B44 pump (similar) I found that a tiny bit of corrosion/swelling on the body, under the gears, caused exactly the symptoms you have described, to fix it I measured the width of the gears (the gears next to the plate, the drive end gears were not the cause) and then used wet and dry sandpaper on a piece of glass  to slightly reduce the gear width, by under 002. This fixed it and saved a bundle of $$$ compared to buying a new one.

I have maybe 6 of these pumps, two I have fixed for spares the other 4, I am 99% certain would respond to the same sort of treatment.

To get the extra 35% flow of the srm pump you can just buy a65 gears and fit them in an A10 body, or get a whole a65 pump and fit the a10 drive end into it.

As you can tell I am too mean to buy the SRM  pump!

[Swarfcut]

 We're only talking a very small amount of swelling to prevent rotation. A paper gasket under the endplate usually works and gives an idea of the amount of material causing the problem. If its a "bubble" it will show as a high spot in the casting, but this may prove difficult to remedy because of awkward access. A worn end plate will also save the day rather than shortening gears. Not for the purists, but an easy backyard fix. I suppose an aluminium foil gasket and a bit of skill with a modelling knife is also worth a try....

 Swarfy.

[edboy]

i have had this fault before and the reason is someones swopped the oil pump gears at some stage. you need to find a drive gear that doesnt bind from another oil pump. they seem to have been crudely manufactured and matched on the bench. bolted together with the drive gear removed the gears should revolve easily.

[Rex]

Fine grinding paste and a lathe/drill soon sorts out a binding gear.
Velocette even recommended this method many years back. The main thing is to ensure the gears go back in the same places and orientation as they were when the pump was opened up.

[muskrat]

Topic split from original.
Cheers

[tomkilde]

Update - I made a pair of very thin (0.15 mm) gaskets to take some pressure off the gears at either end of the housing.  I also polished the mating surface of the "nose" end.  This bike sat unused for nearly thirty years, and it looked like the alloy had softened and oozed into the spaces between the gear teeth.  The pump spins freely now and is back on the engine.  Still eyeing a new SRM or Hepolite pump for a future upgrade.

[Greybeard]

When restoring my bike 9 years ago I decided to change the oil pump. The price of an SRM pump scared the bejasus out of me. I got wind of a newly made pump sold by John Bantam Phelan. His pump promises higher capacity and is steel. The pump was half the cost of the SRM one. I told duTch about the pump and he bought one as well. Does anyone else here have one of those pumps?

[Swarfcut]

 Bergs is in Bantam John's neck of the woods. These pumps are mentioned in the Forum some years ago, and time marches on.

 Drags also offered an own brand replacement pump, and possibly new bodies requiring final finishing, alas beyond my expertise.

 Hepolite pumps appear to be Cast Iron,  (as on later A65's) which I would prefer to the alloy body SRM pump.

 Interestingly the price difference between the latter two makes an informed choice even harder. No point in pricing TOO far behind the market leader......  It needs another competitor to shake up the market.

 Swarfy.

[Greybeard]

Hepolite pumps appear to be Cast Iron, (as on later A65's) which I would prefer to the alloy body SRM pump.

Maybe my pump came from the same source.

[berger]

yes bergs is in b&$d john's neck of the woods but a bit too far away for an accurate shot

[Greybeard]

yes bergs is in b&$d john's neck of the woods but a bit too far away for an accurate shot

He was OK with me 😁