A few weeks ago I ask question about oil pump can't turn with fingers, have to use plires. With help here I worked the gears with valve lapping compound till I could assemble with the 2 bolts and turn with fingers. Today I got to the point to place the pump back in engine. When I just barley tighten the bolts to mount it I can't turn fingers any more. The mounting bolts aren't tighten enough that I'm a worried they will come loose. I have tightened a little more to where the spring lock washers are collapsed and then just a little more. I put the gear on crankshaft that turns pump. I can turn engine by crankshaft on primary side and it turns nice, IE I can't tell the pump is making it hard to turn. Any thoughts? Should I tighten pump any more? Remove it and work more with valve lapping compound? Or go with the way it is?
L.D.

email (option): ldj1002@yahoo.com

You need to spend some more time lapping in the pump...

Keep going until you can turn the pump by hand with the retaining bolts 'nipped' up sufficiently that they won't loosen.

BSA stipulated they shouldn't be 'over tightened' which means you don't have to swing on the end of them...but they should be tight.

When assembling an engine I normally fit the oil pump drive spindle, retaining peg and pump first, so that the bolted in pump can be checked by turning the drive spindle. This is much easier to do without the crank etc. in the cases....

If you can't turn the pump by hand it isn't right...Ian

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

I've just rebuilt my pump (using a new CNC machined body, which I can't recommend highly enough) and I "ran it in" by immersing the pump in a jar of clean oil and used my cordless drill to spin it over. I then washed it clean, put a dab of low strength Loctite on the threads, gently tightened it up and job's a good'un. It turns easily by hand but certainly doesn't feel loose.

email (option): njgreen@bigpond.net.au

I was doing some research and run across a post by Dave Plumb. He had same problem and after some "head scratching" he turned the pump drive spindle 180* and it was fixed. I decieded to try that so I tightened the pump up good turned spindle 180* and here are my results. When I stick my fingers in to turn the pump drive spindle I can do it but is very tight, can barely turn it. One reason is I can't get to it good with my fingers. I slip the timing pinion on the crankshaft without key and I can turn the oil pump by turning that timing pinion. It is a little tight but I can turn it with little force.

I would way rather remove the pump and lap some more rather than damage the pump or drive gears because too tight. However I don't want to lap more than necessary causing too much clarance in the pump. Should I lap more or leave well alone?

email (option): ldj1002@yahoo.com

Hi L.D.

I do not think that you can really lap it more than it needs.
If you use a FINE carborundum paste, it would stop "working"
As soon as the grains can pass around the sprockets,
So the sprockets will stop grinding the metal around it
When the clearance is sufficient.

Noam.

email (option): noam10@gmail.com

['Should I lap more or leave well alone?']...

Hi L.D...Read my initial reply to you first post again...Ian

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

email (option): ldj1002@yahoo.com

For driving the pump with a cordless drill you could use a short piece of 10 x 1 mm tube, pressed oval on one side, works great.

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I took oil pump out and lapped more, put back in and tightened real good and I can turn easy with fingers. BUT @!$#! I then tightned one of the bolts that hold the pump together just a little and it stripped threads in top plate. There was still 3 good threads left so I found a longer bolt and it apparently was just a little larger because I had to actually screw it through the stripped threads into the good threads. I cut it to be flush with top plate then removed it. I got a clamp and put right beside where bolt goes and clamped tight. I put red thread locker on threads, put bolt in and tightened real good and it held with out stripping. A least the pump now turns really easy.

email (option): ldj1002@yahoo.com

I hear Dragonfly sell steel oil pumps - is that right ?
Are they any better then the originals ?
Any experience...?

Hello Mike,

Draganfly are selling new made pumps,
If you give your old pumps as exchange.

I asked them once, and they replied that they do use the
Gears from the old pump (Possibly also the bottom cover?)

According to Ian W. (Sorry for stealing your line, Ian )
No need to replace the original ones,

email (option): noam10@gmail.com

I realize that I forgot to check the oil pump when I rebuilt the engine; it has functioned flawlessly for over 4000 miles, but nevertheless...
So after removing the timing cover I checked the functioning by turning by hand the driving spindle, and it turned freely. Sigh...

email (option): viaconsu [at] planet\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

Hello:

Sorry for coming late to the dance but... I do not understand how you turned the oil pump spindle by hand. I'm trying to identify why my engine is locked and would love to be able to eliminate the oil pump from my list of usual suspects. How can I turn the spindle if the main drive shaft will not turn?
Thanks, Barry in NH

email (option): bcubed77@comcast.net

Hi Barry..You would need to remove the crankshaft pinion from the timing side mainshaft.

This has the worm gear machined onto it that drives the oil pump drive shaft, so with it removed it separates the oil pump and drive spindle from the crank...

However, you will still have trouble getting your fingers to the oil pump drive shaft to turn it as the crank mainshaft remains in the way making access difficult....

As stated in my previous post I fit the pump and drive spindle to the cases before fitting anything else (including the crank) so that I can get at the pump drive spindle to check the pump is free to turn...

As your pump hasn't been out and this is something best checked when you first acquire an M20 I would recommend removing the pump from the crankcase to check it anyway...

Also, have you removed the primary chain yet to confirm that it is the engine that is locked up?....

I would proceed as follows...

1)Disconnect the primary chain to confirm whether the problem is the engine or transmission..
2)If it is the engine, loosen the dynamo retaining strap and retaining nut and slide the dynamo out of engagement with the mag..If the engine is still tight that eliminates the dynamo...
3)Remove the magneto...If the engine is still tight this eliminates the mag from the equation...
4)Remove the oil pump...This will probably require some attention anyway if it hasn't been out for a long time but if the engine remains tight you know you are looking elsewhere...
5)Remove both valves to ensure that neither has 'nipped up' in the guide..
If the engine remains tight...
6)Remove all the timing gear..If the engine remains tight..
7)Remove the cylinder to check the piston, small end bush etc.
If the engine remains tight..
8)Remove the bottom end and check the bearings, crank etc...Ian

Hello Ian:

I have removed the primary chain and the engine is still tight. I did remove the mag pinion, in the timing cover, and was able to turn the points by hand. Would this indicate that the mag and dynamo are not at issue?
Many thanks for the detailed listing steps to check each of the remaining suspects. I had hoped to avoid tearing the engine down as I still am a novice concerning these old gems. Oh well, I guess I'll just have to get on with it and consider it an educational endeavor!
Thanks again to you and all the wise men and wizards on this Forum.
All the best, Barry

email (option): bcubed77@comcast.net