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