[Charlie Sisk]

Seems it wouldn't take too much to build something. A suction hose on the oil drain, going to a pump, then through a filter, discharging into the oil filler spout. Anyone done this ? What pump did you use ? And filter ?
I can see pushing a cart over to the plane, hooking up, and let it run while cleaning all the bugs off the leading edge of the wing. Or updating a GPS. If pumping 1 quart every five minutes, you are done in under an hour.
And as nothing is changed on the engine oil system, no safety issues.
Charlie

 

[Jjackh10]

This.... is what I was talking about in post #6. You do it in the hangar, after a flight and risk nothing during flight without adding any weight to the aircraft.

I plan to use two tubes that are passed down the filler neck. One touches the bottom, cut on a 45. The other tube only goes 1/2 way down the neck. Open the oil door, remove the dip stick and slide in the tubes to the filter and flip a switch and use a timer for the amount desired.... Maybe the same as the last flight.

I have a few gallons of used oil to test the system and the filter media choices.

I think this is a solid 90% solution. You could get virtually all of the oil and address some of Toobuilder's concerns by simply adding a tee and cap at the oil pressure sensor. Connect the cart and pump "clean" oil through all the oil passages so everything is fresh at the next start.

 

[rv8ch]

There are companies that sell oil cleaning carts. The only ones I found were about $1000 which seemed a bit high. If I were building one myself, I'd set up the cart to suck out the oil from the filler/dipstick onto the cart into a reservoir, and then turn on the filter cycle. Let it run as long as you want. Could even heat it so that in the winter you put the oil back in just before flight. Use a glass reservoir and you can see when it's clean. If you want to get fancy, install an inspection port after the filter and use a sensor to determine cleanliness. Another interesting business opportunity - could be sold to aircraft, boat, truck, forklift, tractor, and even car owners.

 

[Jjackh10]

This idea has been bumping around in my head since first mentioned. Could easily adapt it into a real kidney loop with flow through some type of pH conditioner, dehydrator, etc. before the final filtration to help maintain the oil's properties. The two tube/filler neck idea would work better for the former (conditioning) as it would have the benefit of equilibrium to affect oil that was not processed through the loop. The latter would rely on dilution so the bulk oil u level would never be achieved.

@ Several references. Summarizing = "Why does clean oil need to be filtered?" It doesn't stay clean; hence my previous DOD reference (Domestic Object Debris/Damage) for those never baptized in the church of aerospace. Sorry for the reference. Look at some of the opened filter element pix in this forum. Some of that would cause pretty extensive wear being recirculated even in a short flight


You're a smart guy, Sir. Being in Mojave, I assume you have an aerospace job. If all of a commodity is being treated to the level you desire, there's no reason to treat some of it in a bypass loop. Do as you wish and I'm rooting for the outcome you're seeking. A couple of things for you're consideration and I'm done here:

- I'd do a lot of inquiry into the required oil flow for your particular powerplant. As mentioned, the flow is basically constant for a given engine RPM. I'm assuming that oil system flow is similar to the other design parameters related to our machines versus ground dwelling types; the design margins will be much smaller/less conservation. Also, the losses are related to the square of the flow rate so the portioned that gets bypassed will increase at lower RPM. Don't know if that's good or bad but I'll assume that idle speed is the most critical resign point. Before I extracted any primary flow for a proposed bypass, I'd try to get very comfortable knowing that I hadn't swapped one lifeing parameter for another.

- Don't limit yourself to ICE oil filters in your search. Hydraulic systems require much finer filtration; servovalves being the limiting component. Their range of flow design points will also go much lower.

Drift = I got to spend a little time in Moog in NY state for both my aerospace and power industry careers. Dealt with some flat-out stud engineers up there. Anyway, the servovalve motors have very tight clearances, in the tens of thou clearances for their more specialized apps. The related spool which actually controls the actuator flow was even tighter, numbers not shared with me. If you extracted one from the servovalve housing and let it warm up in your hand, it wouldn't go back the bore. Not too much impresses me anymore. Hadn't thought about it in a long time but that memory still makes an impression on me.

Design safe, build safe, fly safe, Sir.

This is a concern with a kidney loop I thought about over the weekend. Pulling a bleed from the engine driven pump might negatively impact oil flow through the rest of the engine. It certainly wouldn't be good in those critical moments at startup. Delaying oil flow to the top end even an additional a second or two when everything is cold can not be good. You'd likely end up replacing rocker arms sooner, and possibly cams.

 

[Toobuilder]

Pulling a bleed from the engine driven pump might negatively impact oil flow through the rest of the engine.

I believe people are making too much of this particular issue. First off, the oil flow for this “bleed off” is minuscule… It’s a .050 orifice! keep in mind that this is much smaller than the other accessory bleed offs that Lycoming designed into the system and that most of us don’t use any longer - namely, the lube supply for the vacuum pump and rotary fuel pump that are now firmly capped. The tiny amount of oil going to the bypass filter won’t even be missed by the oil pump if the engine is otherwise healthy - especially if you are not feeding a vacuum pump or rotary fuel pump.