The hydro lock issue?

[wistech]

Not to get off subject but I just tested an engine on the bench and wil pull 5 inches of vaccum at the inlet fitting. So now we need a valve that can hold up the oil inthe frame and open under less than 5 inches of vacumm while cranking. Im sure once it running it will build up more .

[cannondale27]

Cool.Thats really all we need to know:clap:

I have taken a pump apart and as far as I can see there is definitly a bypass should filter clog.Problem it could force oil back into frame the way it came or force it between pump shaft into the sump,or more likely bypass filter through hole drilled in center of filter housing and then to engine.Here is routing of oil as far as I can tell.Excuse crummy drawing.

[cannondale27]

Filter housing bypass route

[cannondale27]

The culprit

[cannondale27]

I would get fired for machine seat like this!

[cannondale27]

Nice finish for steel one.Incidently both the bypass and checkball springs sure look and feel same tension and size wise.

[61austin]

Is there any way that the seat for the rubber ball can be cleaned up using a large drill bit, and just drill down the edges a little?

[Canniboomer]

Wow, that is a great find that the seat is very rough, and that surely defeats the purpose of a rubberized checkball intended to seal completely. Already this forum is delivering the goods again!

This project would eliminate the spring and ball entirely at that location. As for any change in output oil pressure, any spring or ball is like a valve on the inlet side of the pump, and all valves cause restriction -- without the checkball inside, Wistech would have measured "some" higher vacuum for a higher flowrate and more delivery to pump = higher output pressure. Just the opposite would be a clogged inlet filter causing less flow, it would result in lowered oil pressure, since the pump wants more.

I think our scavengers are capable to pump faster than oil is delivered to them, and possibly delivering more, as with any boost in oil pressure, is certainly worth exploring. The huge disparity of Cannondales oil pressure rates each motor is bothersome, some motors 1.5 psi at idle, and others at 5 or more, however they measured, very inconsistent. In all cases, it seems the scavenger just takes what it gets and spits it back into the frame, maintaining the balance at perhaps a different average sump level each motor, but still getting the job done.

Anyway, this thread has spawned yet another possible idea/project to explore.

"Solenoid operated inlet valve", with dash LED indicator.

Now looking for a small 12V valve, maybe 1/4" full open when activated at low wattage, then full close at power-down, and can incorporate with accessible inlet filter ahead of valve, U-shape path out of frame and back to modified inlet nipple. Maybe less restriction, and with stock checkball removed of course -- what do you guys think? -- any mini-robot tekkies in this crowd?

(to the back-burner for now, after the simpler external checkvalve idea offered above)
returning to main subject -- sorry for diversion.

[cannondale27]

Makes sense to me Dave.Would also be nice to get the hose at back of motor further away from exhaust heat.Maybe kill two birds with one stone.

I think you are right about scavenger pump also.Both rotors together are almost as big as a small block v8!Should be lots of extra capacity there.Removing stock checkball is really not easy though.Plug is pressed in 1/16 in steel with epoxy over it.Broke screws trying to remove it and ended up chiseling it out after drilling.Older pumps used a snapring though.

[cannondale27]

I used a pencil torch and it did help to get epoxy out but the plugs after that are really in there!Drilled and tried using a screw and slide hammer.Just broke screw.Ended up using a small chisel.So if rebuilding a new plug would have to be machined for new style pumps.