Author Topic: Ew 350 oilpump gear type not duplex pump.  (Read 6722 times)

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Offline Dafly

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Ew 350 oilpump gear type not duplex pump.
« on: 25 Sep 2006 at 15:41 »
Hi.. I am in the process of restoring a early 26 ew 350 that has the gear style oilpump not the duplex..is there anyone out there that might have any info on this early Ew oil system.. It looks like to me that there should be some type of a return pump..if there is this one is missing from this motor i have. The timing cover on this motor has only one oil line unlike the duplex pump that has 2 lines..

Offline Ian

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Re: Ew 350 oilpump gear type not duplex pump.
« Reply #1 on: 25 Sep 2006 at 22:00 »
There is some discussion of the EW oiling systems in a post November 2005 titles Oiling on an EW 350 - you have a similar system to my OC600 which, according to Doug's posts, doesn't work very well !! I am hoping I can get mine to work in the next month or so when the bike is rolled out for the first time.

Offline Dafly

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Re: Ew 350 oilpump gear type not duplex pump.
« Reply #2 on: 26 Sep 2006 at 01:16 »
Ian.. Thanks i will look up that info.. Thnx

Offline Doug

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Re: Ew 350 oilpump gear type not duplex pump.
« Reply #3 on: 26 Sep 2006 at 03:52 »
Neither the gear type nor the duplex plunger type EW oil pumps return oil to the oil tank, both are total loss systems.

The discussion Ian mentions is here And a technical article with pictures on the duplex system is here; only a brief mention is made of the gear type pump.

All I can say about the earlier gear type is that Douglas thought so highly of it they discarded it! I think the main problem was the gear pump had to suck oil from the oil tank compartment at the front of the petrol tank, through a mesh strainer, up through the needle restricing valve and through the drip sight glass on top of the petrol tank, from which point could run by gravity down to the oil pump. The front cylinder non-return valve also provided some suction to the line running to the pump (the line bifurcates just before the oil pump.) Any air leaks in the system would destroy the vacuum, impairing the ability to lift oil through the sight glass. So not only does this early system need to be oil tight, it has to be air tight as well. The non-return valve feeds oil into the front cylinder as stated. The oil pump delivers to the end of the crankshaft, then via drillings to the crankpins. A stand pipe in the bottom of the timing chest leads excess oil off to the primary chain. The level in the timing chest is sufficient to submerge the teeth of the lower cam gear. Additionally, the cam spindles are hollow, and receive vapor from the crank case to lubricate the cam bushes. The hand pump was independent and for use when the mechanical pump failed, not to supplement it. It required turning a petcock through 90 degrees to enable it to supply oil to the sightglass.

An illustration  of the early and late oil pump circuit appears in the reprints of "Care and Maintenance of the 350cc E.W. Douglas" available from John Withers here.

-Doug
« Last Edit: 18 Jul 2007 at 12:41 by Doug »

Offline Dafly

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Re: Ew 350 oilpump gear type not duplex pump.
« Reply #4 on: 26 Sep 2006 at 15:39 »
Doug thanks.. I understand now that this earlt system is not very good.. We will see if it works when it comes time to see if it will fire up.. Thnx

Offline davebarkshire

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Re: Ew 350 oilpump gear type not duplex pump.
« Reply #5 on: 18 Jul 2007 at 10:11 »
I've not picked up my new 26EW yet and don't know whether it has this early type of oiling system on it but I do have an Ariel from the same year which also relies upon suction and has also been critisised for the same reasons.

However, the Ariel oil system does seem to work ok but I have noticed the following...
  The drips don't happen for the first few miles as the suction builds up
  The regulator can shut off (vibration) so paint a small red mark to show its normal position
  I usually prime the sight cup before starting after a few weeks of inactivity so that it is not pulling 'air'
  If I don't close the regulator when I stop then the oil keeps dripping for a while

 

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