Today ,after three years re building the heap of parts that constitutes my M 20
I finally fired her up . The good news was that she ran , the bad news that I got no returning oil to the oil tank . So after one minute I stopped the engine,muttering foul language.

I want to pull the oil pump out to test it . I followed the removal procedure in the manual but the pump does not seem to want to come out. When I remove the two bolts holding the pump in place it stays in place and does not want to move . I did remove the little spindle locking pin as instructed by the book . I am loath to resort to more violent methods so if any of you has tips or tricks how to remove a reluctant oil pump I'd be most pleased.

Is there an established method for testing an oil pump ?

The book gives dire warnings against stripping the oil pump . Is there any particular reason for this ?

Any further tips also most appreciated .

Many thanks in advance

Maxim Jurgens
Phuket Thailand

email (option): siamsailing@gmail.com

Hello Maxim,

There are 4 screws on the bottom faces of the pump:

2 are long and protruding into the engine case to hold the pump,
And 2 are short ones to hold the pump's bottom tin cover.

Did you remove the correct 2?

Regarding not to disassemble the pump if nor necessary,
I guess it is in order to avoid wear and tear from purring it
Back together not in the correct way or the same as it was and so on.

Things I would check are:
Are the 2 oil valves free? (Timing cover and sump, in the pump)
Didn't you mix the feed and returning lines at the oil tank?

Is the oil pump drive spindle engaged to the flywheel and accept
It's movement?

In the oil tank, you can check if the feed and return pipes are free
And not blocked, and maybe you even have a circulation,
But the "Straw" which returns the oil is rotten somewhere below
Oil level, so the oil escapes from there back into the tank,
And does not bother going all the way up.

Can you see the few top cm of the return straw (As I call it)
In order to see if oil comes from either side?

http://www.youtube.com/watch?v=Gw_UHLf_FGE

Last thing
May be there is an "Air lock" in the line, air in the pump,
So it cannot create sufficient vacuum to pull the oil through the timing valve.

In this case you can try and force some oil into the line.
It is cot common, but it did happen to me ones..

Noam.

email (option): noam10@gmail.com

All valid comments from Noam.
One of the problems with these pumps, is that they are made from Mazak (monkey metal). When left idle for any length of time, the metal swells and stops the pump revolving freely. This will wear the worm teeth on the drive spindle or even strip them completely.
It's a simple job to strip the pump, where you will find four little gear wheels that connect and mesh with each other. you have to make sure all the wheels turn freely inside the pump body by doing each one individually, lapping the wheel spindles into the body with fine valve grinding past. Clean, oil and assemble and you should be able to operate the pump with you fingers.

Having said all that, it's quite possible that you just didn't wait long enough for your oil to return. But best check out the pump first anyway.

Ron

email (option): ronpier@talk21.com

Many thanks for your quick replies .

1 Am I correct then when I have removed the two long bolts on the oil pump as well
as the spindle holder and the pump does not fall out by itself it is safe to carefully wriggle it out with the help of a pair of pliers ?

2 Can I check for blockage of the oil galleries without stripping the engine ,for example by blowing trough with compressed air or is this a useless excercise ? My problem is somewhere in the engine, not the oil tank ,I think. When I remove the
return line from the oil pump ,leaving the supply line in place and kick start the engine many times ( spark plug taken out ), not one drop of oil comes out of the return side of the pump.

Cheers
Maxim Jurgens
Phuket, Thailand

email (option): siamsailing@gmail.com

The pump should fall away without need to remove the drive spindle. When you are sure that the pump is free and turning and that the little ball in the bottom of the pump that Noam mentioned is clean and free to drop into its seat.
Run the engine and allow time for the oil to collect in the bottom of the crankcase for the scavenge side of the pump to pick it up.

Ron

email (option): ronpier@talk21.com

PS. Good idea to blow all oil-ways out with an airline. Ron

email (option): ronpier@talk21.com

I am trying to get my M21 going after a long sleep. I got it with the timing cover and head removed, don't have any idea why. Anyway I removed the engine shaft timing pinion, that also drives the oil pump. I did this so I could turn the oil pump. I thought it might be full of what ever and wanted to make sure it was free to turn. I wouldn't. So I removed the pump and took it apart, nothing in it. Put back together and can't turn it with fingers but could with plires. From reading on this forum I found I should be able to turn with fingers. I used valve lapping compound and worked the gears in their place in the oil pump till I could assemble it, tighten it and could turn with fingers. I put pump in oil and turned slow with drill and it pumps oil. I am anxious to get it started and see what happens.

email (option): ldj1002@yahoo.com

Hello L.D.

Sometimes,
After a long period of standing idle,
The oil pump drive spindle gets stuck,
Mainly if there was no oil tween it and the tunnel/drill it goes through.

I would check first if the spindle turns freely, with no pump.
In extreme cases it can rip/chew off the engine shaft timing pinion "snail"
And of course, then, with no oil circulating- seize the dry engine.

Noam.

email (option): noam10@gmail.com

Hello L.D.

Sometimes,
After a long period of standing idle,
The oil pump drive spindle gets stuck,
Mainly if there was no oil tween it and the tunnel/drill it goes through.

I would check first if the spindle turns freely, with no pump.
In extreme cases it can rip/chew off the engine shaft timing pinion "snail"
And of course, then, with no oil circulating- seize the dry engine.

Noam.
[/quote]

Thanks for RE:
Yes the spindle turns free. I should get it where I can start it in a week or so. I think it is now ok, we'll see.
L.D.

email (option): ldj1002@yahoo.com

Hi L.D.... ['I am anxious to get it started and see what happens']..


You shouldn't have any trouble..You've followed the correct procedures and BSAs never really suffer from oil pump problems once they have been lapped in properly...

I haven't had a pump failure or oil supply related engine failure in 35 years...Ian

email (option): ian@wright52.plus.com