oil extraction by vacuum - what container do you use?
 

hi folks, i put a couple of hose barbs into a 2 gallon paint bucket with the intention of using my mityvac to extract the engine oil from the dipstick tube. turned out that there was some air leak in the bucket and i couldn't make enough vacuum to get more than a few drops of oil out. what kind of container do you all use for the job, and did you use screw-tight bulkhead fittings or were rubber grommets around the barb fittings sufficient?

(edit: i'm confused because i can't find the air leak, so interested in starting over with a container that is known to work.)

I have a commercial unit. I use it on aircraft, tractors, transmissions, hydraulic tanks, car engines, generators, etc. It uses a compressed air driven venturi system to drop the pressure in the tank. Works pretty well on most applications, but not so well on MB diesels - don't know why. It's not the oil - it sucks out Yanmars, Detroits and Cummins just fine. It prefers warm oil (+100F) & lighter weights (think ATF). It doesn't like diff fluid - too thick. It uses threaded fittings & sealed quick disconnects on the suction side.

My extractor was from an online store, don't remember which. It holds about 10 quarts.

Regardless of the container, I don't think a Mityvac will pull enough vacuum volume to suck the oil out of an engine. You need a much larger pump. I've even considered connecting an electric vacuum pump to the oil sucker to make the job easier.

You might need something like this: Paint Pressure Tank - 2-1/2 Gallon

My car has around 7 gallons of oil. Maybe a 10 gallon metal drum with bungs on them will also do the job. Like they said, the mityvac will not be enough.

Your 1985 300D holds 8 QUARTS of oil.

Mityvac make oil extractors. I have the MV7201. You can't remove the oil with of those little Mityvac hand pumps!

I use an elec vacuum pump and a five gallon helium balloon tank and 3/4 inch vinyl tubing with 1/8 inch walls hose clamped onto dipstick tube. Mityvac hand pump will definitely work. It will take a lot of pumping though. You can find out how much by evacuating the tank down to 25 inches of Hg and count how many strokes it takes.

thanks funola for describing the hardware. how did you get the figure 25 inches, is that the height of the oil circulatory system?

i don't mind it being a lot of pumping as this isn't something that happens often. if it becomes intolerable i will buy an electric pump.

You could connect the engine vacuum pump to the container, and suck the container into a vacuum, then close a shutoff valve to contain the vacuum, then shut off the engine, and connect the container to the dipstick tube and suck it out.

But a plastic 5 gallon container will not hold much vacuum before it implodes. You are going to need a steel drum like the helium tank, or similar, or a steel round gas can. 25" of vacuum is a LOT of atmosphere to hold back...

vstech, i will keep an eye out for a steel tank. using the engine to pump out its own oil is brilliant.

funola, rather surprised to hear that your hose was "clamped onto dipstick tube". this sounds a lot less messy than dipping it in, thanks for the tip.

25 in hg is the max vacuum my mityvac is rated for, btw. each squeeze moves 1 cubic inch of air. a 2 gallon bucket is 462 cubic inches. now i have no idea what the pressure would be if i squeezed the trigger 462 times.

Used this unit and it works like a charm,

Pela 6000 Oil Extractor, IDParts.com

I have a basic Ebay vacuum oil system, didn't cost much at all, I have found on some cars (like the Mercedes) it fits down the dipstick fine, on others I need to put it around the dipstick tube - both are pretty mess free.

I made the number up because it's a good number to have. In reality I think 20 inches hg will do. The real test is after you're done remove the drain plug and nothing should come out, not even a drop.

Using the dipstick tube as the suction tube is the way to extract oil per the FSM. With the vinyl tubing and clamp I can extract the oil and not spill a drop if I'm careful.

That unit's 6 liters capacity will spill oil on a w123 with 7 quart sump.

I use this one... Portable Generators, Pressure Washers, Power Tools, Welders | Northern Tool + Equipment

OK, clearing this up. yes i can build pressure with the mityvac and yes it takes too many pumps. i didn't have an air leak so much as an unrealistic expectation about my ability to build vacuum in the bucket's volume. i could have finished the job but my bucket was collapsing after a couple of hundred pumps, at about 5 inches hg. since so much absolute vacuum is needed (h/t funola, vstech), it seems a metal drum is called for, whatever the source of the vacuum.

thought experiment: anything else productive to do with bigger vacuuim reservoir in the trunk? maybe provide a vacuum wand for the interior?

I use a Tempo Oilboy. It used to be the most common extractor on the web, but no longer made. It's similar in design to the Mityvac extractors, but can't reverse to fill by pressure. It only holds 4 quarts, so I have to do two pulls on my 190d. To store the tubes, which are messy after use, I soldered a cap onto a length of 3/4 inch copper plumbing pipe.Hang it or lean it against the wall and there's no mess.

A 20 pound propane tank sounds like the perfect solution, no?

I'm pretty sure they are threaded 3/4" NPT which would allow almost any imaginable fitting configuration. One connection to attach a vacuum source for pulling the reservoir down, another for the fluid connection, and last how about a Schrader valve to add air pressure. That way you could pull vacuum, suck oil and then blow the used oil out to empty the tank if you stand it on its end.

Probably need a valve for each of the connections or the Schrader will leak when the tank is pumped down.

They sell dual valve threaded connections valves that have a dip tube to remove liquid or vapor... Ac recovery tank valves.

Kind of heavy to lug around?

Actually why have a vacuum tank at all? Once you create a siphon the oil should just flow into a shallow pan if the oil level is above the pan level. To get more height, put car on ramps. Only need enough vacuum to create the initial siphon. Maybe about 1 or 2 ft of oil or say 2" of mercury should do it.

Even with commercial vacuum extractors, they work best if put on garage floor so that oil level is lower than sump level.

On the other hand, could forget about vacuum. Just remove sump plug and let oil drain out by gravity ;)

Bookmarking topic for reference. I need this method of crankcase extraction for most of my engines these days.

this is what i expected to happen the first time i tried, but i couldn't figure out how to start the siphon with the mityvac. is that possible? i didn't want to put my mouth on the tube nor run oil through the pump. does it just come down to pulling the tubing off the barb at the right moment?

My mityvac came with a small, 250ml??, bottle which I've use for brake line purging and other lite suction duties. I guess you can use one or two plastic hose clamps to prevent oil getting into the pump.

Oil is pretty thick. Siphon may not have enough suction to overcome adhesion.

I've used this method to drain excess transmission oil. You can draw the oil into the tube with the mityvac, pinch the tube while you disconnect, and put the end of the tube in a pan and release. It does work, but takes a few tries to get it right. And the oil has to be hot.

Yes, getting oil hot would be required. It speeds things up a lot even when using the Mityvac vacuum extractors.

I haven't tried using the hand pump, but I guess you would need a valve of some sort. to allow the pump to be removed before oil gets to it.

But really - a proper vacuum extractor is cheap. So is removing sump plug. So unless you just enjoy messing about with dirty oil, why bother :D

MMMMMM...

http://4.bp.blogspot.com/-UOLAgoye5Z...lack+teeth.jpg

if this approach works, how to avoid sucking old oil into the vacuum system pump upon depressurizing an already slightly oily tank?

I use two connections for the tank... One NEVER sees oil, so no contamination from the dirty oil.

I think you meant you use two tanks in series, the main tank and another small safety tank.

Do yourself a favour and purchase one designed for the purpose.