WD Oil Pump Problem

Dougie · Post by **Dougie** » Mon Jan 28, 2008 9:34 pm

Hi Group

Help required please!

I finally got my WD Matchless back together on Sunday after nearly a year in bits. I stripped it down because of an oil return problem (oil wasn’t returning satisfactorily to the tank and it was collecting in the crankcase and getting past the piston rings).

When I fitted the new oil pump spindle and its guide screw into the crankcase I checked particularly and thoroughly that the spindle (pump) was both rotating and reciprocating when I turned the crank. Happy with that I then, gradually and slowly, rebuilt everything.

After two goes at setting the ignition timing the bike was a one-kick starter but, imagine my horror when I noticed that no oil was being pumped at all!!!!!!!!!!

There is no restriction between the oil tank and the crankcase. Oil is reaching the infeed port at the bottom of the crankcase but is not being pumped anywhere so, unsurprisingly, there is no oil return (at all).

It’s almost as if the pump needs priming for it to work but I can find no reference to any priming instructions in the manuals. Is this an obvious one to everybody except a numpty like me? Or have I got a full-scale, 24 carat problem with the (new) oil pump?

Is there an easy cure? Or even an easy check?

I’m really relying on you guys to poke fun at me for missing something blindingly obvious and very easy to rectify without so much as removing anything! Here’s hoping…

By the way, I could find no reference in the manuals about aligning the spindle cut-outs with anything so I just "shoved" it into the housing.

itma · Post by **itma** » Mon Jan 28, 2008 9:44 pm

This is a regular frightener for the novice.
remove the oil filter cap, and pour oil into the filter; while this is being soaked up, take off the rocker box hatch, and shove a cup ful of oil in there. if the oil in the filter has been all absorbed, fill it again and put cap back on.
go and Make a cup of tea.
by this time it all should have found its way to the sump; start the bike and watch the return in the tank.
Myself, I like to then squirt some oil directly into the return in the tank, this ought to spit back out, and reassure you all is well.
A little more running and it will settle down to an intermittant spit.

I am assuming you checked cleaned out the return drilling in the crank case of course?

Dougie · Post by **Dougie** » Mon Jan 28, 2008 10:00 pm

Ken

You are already my hero!

If this little dodge works you will be up to Superhero status! I ain't gonna be able to try it until the weekend (work is really hectic at present) but I like the sound of it so much I'm convincing myself that all will be okay.

Incidentally, the crankcases were split by Goddens the engine builders, who checked, repaired, cleaned, and re-assembled them so all should be well.

Thanks for that tip. I will report my findings in due course.

Biscuit · Post by **Biscuit** » Mon Jan 28, 2008 10:08 pm

Are the pipes on the right way - TRBF- top return, bottom feed.

Dougie · Post by **Dougie** » Mon Jan 28, 2008 10:13 pm

itma · Post by **itma** » Mon Jan 28, 2008 10:25 pm

mind you if none of that works you are in deep..........

Don Madden · Post by **Don Madden** » Tue Jan 29, 2008 2:20 am

To insure oil is getting into the feed pump & to bleed air, remove the screw plug at the front of the pump, just behind the front cover plate. Oil should run freely out of the 1/4in. hole.

When sure oil is flowing into the feed pump, put the plug screw back in & remove the pipe feeding the valve gear from the front cover plate. When the engine runs, oil should dribble from the front plate fitting.

The pump works very slowly, 1947 & later, (2-start), pumps stroking once per 8 crank revolutions & pre-'47 only half that but these engines need very little. If the oil does pump out of the front fitting, it will likely be sent to the big end as well.

Ken's instructions will verify the return circuit is happy.

Cheers, Don.

Dougie · Post by **Dougie** » Tue Jan 29, 2008 6:23 am

Thanks Don, At the moment it seems that oil is reaching the crankcase feed port by gravity but not going anywhere else!

I will do all that has been suggested; in fact I'll do anything to avoid the inconvenience of tearing it apart again!

I can only get on it a weekends and only then if the weather is good as I have to work outside the garage. I will report back in due course.

Dick Hobart · Post by **Dick Hobart** » Tue Jan 29, 2008 9:03 am

Hi Matt & Neal,
Some great advice there, but you've not done the old chestnut of putting the paper gasket on the wrong way round and covering the holes have you? Also I wonder if you're panicking unnecessarily - how long are you giving it? My WD always takes 3-4 minutes before any oil starts coming back. Seems an age when you're watching and waiting but as Don says these pumps work very slowly and even on an all day event in mid-summer it still runs as cool as a cucumber - on grade 50 oil, of course! Good luck - Dick.

crawsue · Post by **crawsue** » Tue Jan 29, 2008 4:45 pm

All great advice,but the burning issue is.....who's Dougie