I've just gone to the Matchless G3 after leaving it to stand for about two weeks and it's managed to leak the entire contents of its oil tank into its drip tray? This is all leaking straight out of the breather pipe, but why would it just keep running through at such a rate? An oily floor comes with the territory I know, but this is rediculous!?!

Try removing the oil pump covers and retaining screw, get the motor on TDC on compression stroke and then remove the pump and re-insert it so that it is as far forward as it will go when the screw is inserted, it make take a few attempts to get it right, this should lessen the chance of it wet sumping as the oil ways are then covered by the pump. While you are at you should check the pump housing for scoring. This should help. I'm not in favour of the wet sumping valves as they tend to starve the motor of oil at higher RPM (which in reality you nearly always ride at)
The motor should nearly always want to stop at TDC, if it dosen't you can always kick it until the compression is felt after you've stopped the engine.
If you find the pump housing is scored try having a word with Andrew engineering and see if he can make an oversize pump which you can then hone out the housing

email (option): davmax@ntlworld.com

Hi,
For a Matchless to sump the oil has to pass round the pump spindle and the crankcase. You need to strip it and see what sort of fit the steel rotating pump spindle is in the crankcase, check for any play or bad scoring. If it is slack or scored you will have to bush the crankcase (not easy) Also while you have it down check the timing side main bearing bush, if this is slack it can cause the worm drive on the crankshaft to put pressure on the oil pump spindle. This timing side bush needs to be a good fit on the shaft as this is where the oil pressure is built up and forces it to the big end.
Check it out, it is not a good idea running it like that.

Tim W

email (option): t.j.walker@btinternet.com

Cheers chaps, thanks for the pointers. That's my weekend sorted out then! I'll strip it down, see what it looks like inside and I'll report back.

Don't worry about it. Just drain your crankcase before every ride. Been doing it for the last 9 years.

That's one way of doing it Douglas! I like it. I would do just that if it wasn't for the amount it's getting through. A good gulp is one thing, but the greedy old bugger is emptying it's entire tank!

As Dave explained, if the oil ports are exposed then no matter how new your oil pump system it will still leak down.It's guesswork to know if the pump is in the right or wrong position.

http://f1.grp.yahoofs.com/v1/gHfGUGocGapw_OZkq8OFh0OmQbrYTcEcoaKnssF-6Nr70SN-Ntf9ovqh2gP0bogtkVQUqoz3qnEnJC0xr_w9bOOWMzLaKgs/oil%20circuit%20anim.gif

Just copy and paste. Don't know why it doesn't always highlight? Anyone explain?

email (option): welbike@wish.net

I thought we'd been through this before a while back, but I couldn't find the thread again and couldn't remembr what the outcome was. I don't seem to be able to get either of these links to work either.

Copy and paste works for me.

Ebay item number 170950317789

email (option): cooperbaumber@yahoo.com

These sound great, the perfect solution. I'll strip it all down and see if there is anything more sinister going on before I buy one though. Has anyone out there already bought one of these valves? Do they work, do you have to clean them out every so often?

As I have said in previous postings on this subject personal experience tells me these valves are NOT the 'perfect solution'..and in some cases the results of fitting one are disasterous...for example complete failure of a Norton Commando engine after 20 miles....
There is no more a 'one solution fits all' valve for varying types of oil pumps with varying degrees of wear than there is a 'one carb suits all' carburettor for fuel delivery that suits all engines..
Just think about how the valve works..it relies on pump suction to lift the valve from its seat against spring pressure...Does your pump generate enough vacuum to do this?..and how did they arrive at a 'one spring suits all' spring pressure?
I note they say they carried out tests on a BSA single..That has a sprung loaded Anti Drain valve on the 'downside' of the feed pump which is pushed off its seat by pumping pressure at 7 psi ...As the oilpump will produce over 60 psi at low to moderate revs it is effectively impossible for the valve not to operate...(it also has a valve without a spring in the base plate of the pump so the engine already has 2 anti drain valves fitted.)
The usual problem in this case is an old spring or a ball that is not seating correctly..or foriegn matter/damage on the seat of the pump valve. But hey, ignore all that and just fit a valve!....
If you have a leaky gasket don't trouble yourself fitting a new one! just buy this welder and weld the cases together!.
....My advice would be to treat the cause not the symptom...and don't fit anything into the feedline to the engine that might compromise the oil supply..Ian

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

Exactly what I was worried about Ian and why I asked, thanks for the advice. I intend to strip it down and investigate before doing anything drastic. As with many such aftermarket things, there are pros and cons and I wasn't happy about just sticking this on untill I'd had some feedback from you knowledgable chaps out there. If the bike was meant to have a non return valve on it, I suppose they would have fitted one in 1940? It looks like a nice bit of kit, but I was also worried about the 'one size fits all' approach? Could you really put one on a Fizzy or a Munch Mammoth and it would work just the same?

If you fail to solve the problem..which personally I feel is the correct approach, then the best solution is a plain 'on/off' valve with the closed position rigged so that it earths the spark...that way you can't start the bike without opening the valve. Another solution fitted on early BSAs, was a rod between the petrol tap and the oil line valve...Opening the petrol valve also opened the oil valve!...clever....Ian

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

That is damn clever! Nice simple, effective engineering, you can't beat it.

Stripped it down, cleaned the pump, put it back in as Dave suggested and hey presto, a clean garage floor!! There was no scoring and everything seems in good condition with no play. So far, not a single drip of oil, it runs nicely and doesn't spray it out of the breather either, so fingers crossed it's problem solved. Thanks for all the advice as always chaps.

I'm sorry Bill, but all you've accomplished is clean and reassembled the pump. Next time you start it the pump will be at a different position. The oil ports won't necessarily be closed when at top dead centre as it doesn't work like that.

That's why you set it at TDC on the compression stroke, as the engine will always try to stop on the compressions stroke even if you use the decompression lever to stop it, just to be really sure, when your engine has stopped you can nudge it up to the compression stroke.
I have another problem on one I'm doing now (a 500 trials bike) and that bike only leaks oil when it is running and dosen't leak when it's stopped!

email (option): davmax@ntlworld.com

It was leaking a huge amount and almost constantly before, but since doing what Dave suggested, I've done about 35 miles on it and started and stopped it about 10 times and not a single drop has gone on the floor, so fingers crossed, I think Dave may be onto something