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Re: Oil pump - how to check

Henk Joore
Gary
Thanks For a very helpful and easy to follow set of instructions Ian- one for the technical archive maybe?

Gary


Good idea Gary and already done.

Henk


Henk, Gary made his suggestion in January. Where have you been for the last ten months ?

Re: Oil pump - how to check

I tried to be cynical Rik.

email (option): ahum@quicknet.nl

Re: Oil pump - how to check

Draganfly used to advertise with steel body oil pumps.
Would they be any better ?
Anyone tried one ?

Something else; i've never even seen my oil pump since I bought the bike in 1973.
It pumps all right, but should i take in out and check ?
(some people say "if its not broke, don't fix it" but I'm starting to worry now...)

Re: Oil pump - how to check

No need to take it out if it is working.
The one in my bike works. My spare engine didn't have one so stripping one I got to ensure it is able to work. Before I took it to bits it would not move freely. It wouldn't turn easy even with pliers. So using this opportunity to learn how to service one. Probably never taking my working bike oil pump out.

Paul Crisp

email (option): bsa945@btinternet.com

Re: Oil pump - how to check

You can leave it if it's running...

However, bear in mind the 'tight' condition arises from a deterioration in the material of the Mazac pump body..This is an age related problem and can happen while the pump is in the bike...

It can even happen to a NOS pump whilst on the shelf as well...

I have stripped many engines that were running with an overly tight pump..

Of course, the engine has plenty of power (even the M20 ) to drive the pump in this condition...The result though will be a prematurely worn oil pump drive...

Dropping out the pump is a relatively easy job with the BSA so I would say it's a job worth thinking about during the winter months when the bike isn't in use as much...Ian

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

Re: Oil pump - how to check

Anyone know what size and part number the fixing bolts for the oil pump are. Not the ones holding it together, the ones to mount it to the bike.

Cannot find a part number for these?

Paul Crisp

Re: Oil pump - how to check

The thread of the bolts are 1/4" Whitworth but they have reduced flat heads..Part number 65-2604...Ian

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

Re: Oil pump - how to check

Thanks Ian
Have ordered a couple, now received in post. But when trying to screw in the bolt goes a couple of threads then binds. Do not want to force it, could it be a different thread?

 photo Oil pump mounting 1d_zpsih62t7tw.jpg

 photo Oil pump mounting 1c_zpstafgsdbj.jpg

Only goes in a couple of threads

 photo Oil pump mounting 1_zpsj6als8xg.jpg

Re: Oil pump - how to check

I would start by running the tap down the bolt holes...it is quite possible that the threads have been burred by the use of worn/damaged bolts previously...

This will ensure the crankcase thread is good...Then retry the bolts...

If they are still tight use a WHITWORTH die to run down the thread taking the minimum of material from the bolt and then try it again...

If you run a die down the bolt first you may still find it is tight in the hole but you will now have an undersize bolt which may be loose when you tap out the hole...

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

Re: Oil pump - how to check

From the point of view of 'best practice' it's worth noting here that UNC and Whitworth are not interchangeable threads..
Whilst the pitch (TPI) numbers are common up to half inch the thread form is quite different..

Whitworth has a 55 degree included thread angle and UNC has a 60 degree angle...The base and crests of the thread teeth are also different...

So, whilst you can physically mix the two, the fit of the nut to the bolt and vice versa would not correct in that case...

It should not be regarded as good practice to mix the two forms and this should be avoided if possible..Ian

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

Re: Oil pump - how to check

I normally bin the original bolts as they are a pain to undo once fitted especially when engine is fitted into bike.I replace them with allen bolts with a drilled head so I can lockwire them, the advantage of using drilled allen bolts is you can just nip them up then lock wire them, this also helps to prevent distortion of the pump body..Dave

Re: Oil pump - how to check

Thanks
Now getting myself a die and tap.(set of three taps)
just checking website for thread sizes, I see what you mean by angles of thread.

http://mdmetric.com/tech/tict.htm


 photo Thread Angles_zps8lzkdxd4.png

Re: Oil pump - how to check

If the thread in the hole is damaged/burred which is possible as it's an original not a new thread, and you reduce the bolt with a die to try and make it fit it may still not go in...

If you then tap the thread out in the crankcase, the bolt, which has already been reduced in diameter in an attempt to make it fit a damaged thread, will then be undersize and thus slack...

It seems more logical to ensure the old thread in the crankcase is functioning properly before thinking of altering a new bolt which may have nothing wrong with it...To check the thread on the bolt a whitworth nut should be used..

Any comments regarding threads are only to point out that mixing threads is not good practice and a die of the correct thread should be used to clean up threads...(or the appropriate thread file)..not a nut of the incorrect thread...

I'm not being either pedantic or critical...I just think it is best to describe the correct methods ...Ian

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

Re: Oil pump - how to check

Yep
Got a die and tap set for the 1/4 inch Whit thread.
Used the taps to clean out the thread in the casting and it worked, the New bolt fits smoothly in now. No movement, no slack.

Paul C

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