Author Topic: 2 3/4 oiling system  (Read 6082 times)

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Offline runmark

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2 3/4 oiling system
« on: 04 Apr 2016 at 22:12 »
Hello all,  I have a 1924 SW with an oiling issue.  The oil pump delivers oil to the sight glass chamber without any problems.  The air vent by the metering valve is clear.  Problem is oil will not leave the sight chamber.  If I try to charge a dry crankcase the oil does not flow to the engine.  When running the oil also does not flow to the engine.  I have a rebuilt non return valve using spring and disc from the club.  There is a crankcase breather on the top of the left case, this dumps via copper tube onto the primary chain.  There is no non return valve on the breather.  I have read about breather check valves in the timing chest with a stand pipe.  I do not appear to have either.  Presently I charge the engine through the aforementioned breather but would like to travel more than10 miles at a time.  Any help would be appreciated.  Mark

Offline Hutch

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Re: 2 3/4 oiling system
« Reply #1 on: 04 Apr 2016 at 23:57 »
Non return valve in back to front?

Ian

Offline runmark

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Re: 2 3/4 oiling system
« Reply #2 on: 05 Apr 2016 at 01:24 »
in the front

Offline Hutch

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Re: 2 3/4 oiling system
« Reply #3 on: 05 Apr 2016 at 02:33 »
Sorry Mark I possibly didn't explain myself very well.

The one way valve needs to let the oil into the crankcase, but stop the crankcase pressure blowing back into the oil dripper (sight glass chamber). It is possible to fit the one way valve so it will prevent the oil from going into the crankcase. I presume the dripper is filling full with oil?

 If you take the non return valve off the crankcase and have it still connected to the dripper can you get oil to cone out of the open end? If not then check the orientation of the spring and disc with respect to oil flow direction.

hope this helps - Ian

Offline Hutch

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Re: 2 3/4 oiling system
« Reply #4 on: 05 Apr 2016 at 02:44 »
you may need to apply a small amount of vacuum to the open end to overcome the spring tension inside the one way valve....

Offline eddie

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Re: 2 3/4 oiling system
« Reply #5 on: 05 Apr 2016 at 07:22 »
Mark,
         To work correctly, the lubrication system relies on a partial vacuum being generated in the crankcase. To achieve this, there must be no extra breathers or venting to the crankcase itself (Mr Douglas even fitted brass shields to the main bearings to prevent excess breathing through the bearings). In order that the crankcase should be able to breathe, a non return valve is fitted in the timing end of the crankshaft - if this is missing or damaged, it will seriously affect the operation of the lubricating system. The valve assembly is just a ball and very light return spring retained by the screw that holds the crankshaft timing pinion. If the bottom end of the engine is assembled correctly, this valve should 'fart' at you when you turn the flywheel by hand! The vented gases and oil mist passing through this valve then lubricate the timing gears, etc. Finally, the gases pass through the short standpipe in the bottom of the timing chest into a pipe the aims at the bottom run of the primary chain.
Hope this helps,
                       Regards,
                                     Eddie.

Offline runmark

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Re: 2 3/4 oiling system
« Reply #6 on: 05 Apr 2016 at 12:42 »
Ian, The non return valve is installed correctly but it does not allow oil to flow.  I will try the vacuum trick to see if the disc will come off the seat.  Could the spring be too stiff. 

Eddie,  I will pull the timing cover and check for the crankshaft valve.  I do not have any outlet from the chest other than the drain plug in the rear of the chest.  What purpose does the fitting on the top left crankcase serve if not a breather, it is open to the air.
                                                         Thank you men.

Offline eddie

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Re: 2 3/4 oiling system
« Reply #7 on: 05 Apr 2016 at 16:01 »
Mark,
         I would suggest that, at this point, it might be a good idea to remove the non-return valve and carefully check it out. Inside the body there should be a very thin disc that is free to float between the 2 seats - that is, there shouldn't be a spring to keep it against the seat. One seat should have 4 slots to allow the oil to pass - the other seat (without slots) prevents oil from returning. Make sure you have flow in one direction only, i.e. into the engine.
 With regard to the extra fitting on the top of the crankcase - there is usually a tap fitted here so that it is easy to prime the crankcase with extra oil should it be found necessary. The tap should be turned off when running. Some later engines just have a blanking plug instead of the tap. As you have a blanking plug in the timing chest, instead of a pipe fitting, maybe this and the one in the top of the crankcase have been swapped at some time,  this could possibly be the cause of your oiling problems. If the timing chest cannot vent, then the crankcase wont either, and crankcase pressure will build up, preventing oil from draining from the tank.
Regards,
             Eddie.

Offline runmark

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Re: 2 3/4 oiling system
« Reply #8 on: 05 Apr 2016 at 16:35 »
Eddie,  Will take your advise and install a tap on top left crankcase, remove the non return spring and install a vent tube where the current timing chest plug is.  Also will check out the crankshaft breather.  Is this all correct?  Thanks again, Mark

Offline steveale

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Re: 2 3/4 oiling system
« Reply #9 on: 05 Apr 2016 at 19:47 »
I experienced a poor seal in the sight glass installation which exhibited an oil delivery problem.  Air must have been escaping around the gasket and the oil would back up and fill the sight glass when doing the initial pumps.  Once sealed, enough pressure could be developed to open the valve going into the motor and oil now flows quickly on the priming pumps...

Offline Hutch

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Re: 2 3/4 oiling system
« Reply #10 on: 07 Apr 2016 at 04:27 »
Hi Mark,

How are you going with your problem? If you are satisfied the non return  valve is functioning correctly, the only other thing I can think of is that you have a blocked pipe between the sight glass and the non return valve? If you hadn't already done so, maybe taking the pipes off and check they are clear would be worth a look?

Interesting what Eddie says about not having a spring in the non return valve.Based on this comment, I dug out two non return valves and checked ! One had a spring and the other didn't.  I had a look in the 2 3/4 parts lists and Douglas specified a part number for the spring (424D) so at some time Douglas appear to have used them. So i did a quick experiment and found out that by blowing through the valve (in both directions) with good old lung power there didn't seem to be much difference in performance between having the spring and not!  :). The spring is very weak so the effort required to open the valve is not very high. Probably why they work happily without the spring. I guess with the spring in place a small amount of oil would remain in the feed tube when the motor was stopped, instead of draining into the crankcase straight away, but I guess this amount would be small so probably doesn't matter?


Ian

Offline steveale

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Re: 2 3/4 oiling system
« Reply #11 on: 07 Apr 2016 at 13:27 »
I just went through the spring/no spring research on my 1913 crankcase valve.  Not only did it not have a spring, the bore in the fitting had no taper to even accept a spring.  Any spring inserted would just fall into the oil channel in the top of the motor.  I did the same "lung test" and realized that the disc would seal and un-seal with the vacuum and pressure generated with the engine just fine without a spring.  A couple of the experts on here validated same.  The valve on the bottom of my oil pump however, did have the spring.

Offline runmark

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Re: 2 3/4 oiling system
« Reply #12 on: 07 Apr 2016 at 13:59 »
Took Eddies advise and plugged the top left crankcase and installed the drain on the timing chest.  Oil did feed for a while then stopped.  Still had the spring in the non return.  Next step will be to chuck the spring.  I am making progress. Thanks everyone.  Mark

Offline steveale

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Re: 2 3/4 oiling system
« Reply #13 on: 07 Apr 2016 at 15:57 »
Eddie,

My machinist and I were trying to figure out what those brass retaining plates functionality were on the crank bearing end cases.  We just thought that they were to retain lubrication in that bearing area due to the drain hole positioned to house a certain level of lubricant in the area.  Helping create "seal" for pressures was something we had not thought of....

I put a more modern sealed bearing on the flywheel side (sealed on external side only), to help keep lube from exiting the engine is this area.

It's working so well, I am considering doing the same in my gearbox...good lord do those things puke the lube.

Offline graeme

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Re: 2 3/4 oiling system
« Reply #14 on: 08 Apr 2016 at 03:50 »
Getting off the topic of the 2 3/4 oiling system, but if you want to keep lube in the gearbox, use semi-fluid grease. Warm it up to initially fill the box, or it will take weeks to drain through the narrow necked funnel required!

Offline Chris

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Re: 2 3/4 oiling system
« Reply #15 on: 08 Apr 2016 at 07:56 »
Hi
I have a vintage oil syringe originally intended I think for filling car rear axle differentials. It is about 1.1/2" diameter and 7" long. The spout has a screwed cap on the end. I have made a tapered brass nozzle to fit in place of the cap. The body of the syringe can be filled with semi liquid grease quite easily using a spoon if not willing to wait for the grease to run in. Filling the gearbox though its small orifice is a matter of a few seconds as a load can simply be squeezed in by depressing the plunger. The nozzle is then replaced with the cap to prevent leakage. Chris.

Offline Black Sheep

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Re: 2 3/4 oiling system
« Reply #16 on: 08 Apr 2016 at 13:37 »
If you wish to use a non-vintage syringe, your local pharmacy should be able to supply a plastic 60ml syringe (best type is for enteral tube feeding) for a few pence. So useful around the shed!

Offline steveale

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Re: 2 3/4 oiling system
« Reply #17 on: 08 Apr 2016 at 14:28 »
I'm using a 00 semi-fluid grease...it still slings it like mad.  Good news is the primary chain stays lubed.  Fortunately it only seems to come out the primary side so it is not impacting my drive belt at all...