aero 250 oil pump

[Tazmantic]

Hi all been a while as the bikes have been sat but yesterday I started dougal 2 and it took some starting then smoked like I don't know what so presume the engine was well over oiled but anyway to my point the drip feed in the sight glass worked fine, today I started it and the drip feed would not work at all.... in the end I removed the sight glass and removed the ball and spring and it worked fine again so was just wondering how much pressure should the pump supply?? if I run the bike with the sight glass off oil comes out the hole and if I put my finger lightly over the hole I can feel it pumping but if I press it stops..

Thanks in advance

[Tazmantic]

Ill add to this it pumps oil back to the tank fine 

[Aero]

Perhaps the relief valve  in the pump is sticking open slightly?

[Tazmantic]

Thanks aero I'll have to take the plate off and have a look

[Tazmantic]

Took side plate off today and found when I put an air line on the oil feed pipe it blew out round the oil pump retaining screw slightly so maybe it was sucking a bit of air (and why the engine filled up when it was stood) so fitted a fibre washer behind the screw head (not sure if there should be one) also swapped the spring for the relief valve with one out of a spare pump as the one in the spare was a bit stronger.

Connected it up to the oil tank but still didn't seem to want to pump through the drip feed till I bled it via the screw on the top of the oil pump then it worked fine but I just wonder how I could do this once fitted??

[Tazmantic]

so would the ID size of the feed pipe make much difference? and what should the drip rate be?

[Hamwic]

Generally oil pumps would rather pump air than oil, given the opportunity. If the oil level drops below the level of the top of the gauze in the tank, the pump will suck air through the top of the gauze, rather than the oil surrounding it. I have recently taken out a couple of supply gauzes that had been unmolested these many years, and was astounded by how clogged they were, and yet oil appeared to drain through them. In fact it was only a trickle, and when asked to provide a proper flow - nothing doing.  If the oil tank has drained into the engine, you could have been pumping air, until the tank was replenished by the return? Many other makes suffer from wet-sumping, and it is tempting not to refill until after a start as the usual result is oil cascading out of the tank cap or breather, but it is usually better to drain the crankcase first.

On a cold morning you could wait all day for SAE50 to drain down a 1/4" bore pipe by gravity (loss of head), so yes the pipe bore does have an effect. Hence the recommended use of thinner oils in winter. If the pump action is weak or leaky - perhaps at the pump to cover face itself - it will keep itself happy sucking free air. If the ball valves are gummed up, then all action is lost. A hot air gun used with caution might wake it up if the oil has all but solidified in the passageways.

I would remove and clean the filter in the tank, check the air hole in the cap, the unions for cracks or leaks. I would check the the pump itself is functioning by running a feed to it from a separate header tank - e.g. a tin hanging off the handlebars with a length of clear pipe as the feed pipe to the pump, and see if things improve. If no change, it's the pump. If OK, then it's the tank end.

Keep us posted!
Doug

[Tazmantic]

Thanks for the info and sorry for the late reply, well it did seem to be working ok but now on top of the other issue I have it seems to not want to pump again till the oil gets warm. I must see about changing the inlet pipe as it's not even 1/4

Thanks again