How can I use my air compressor as a fluid extractor? - PeachParts Mercedes-Benz Forum

shertex · #1 03-17-2018, 01:10 PM

Doing an oil change on the 98. Oil was at operating temp...but it's a cold day so as thing cool down it's taking a loooooonnnngggg time to extract the oil with my Mityvac extractor.

I have a decent air compressor. Is it possible to hook up something to the compressor so that the compressor could provide the vacuum to extract the oil? I'm thinking some something analogous to a paint sprayer...only instead of sucking paint I suck oil...and instead of spraying on a wall I spray into a receptacle.

torsionbar · #2 03-17-2018, 01:18 PM

The dealers use oil extractors powered by compressed air. So yes, you can buy such a thing. They're only a few hundred bucks, so not terribly expensive. It saves time when you're doing 100 oil changes a day, but for a home hobbyist, a manual pump extractor like your mighty-vac is more common.

If the outside temperature is the only problem with your current setup, I'd recommend investing instead in a wool sweater and knit cap. Or install a mini-split HVAC system in your garage so you have a more comfortable place to work.

Phillytwotank · #3 03-17-2018, 01:32 PM

something like this
https://www.infinitytools.com/venturi-vacuum-system?gclid=CjwKCAjw-bLVBRBMEiwAmKSB83M7Ts2w5yJAtmZRvv1RQNmeSLtcmVvEDYYS6P12a5hvrvlcynE9yBoC1vsQAvD_BwE

vstech · #4 03-18-2018, 02:27 AM

There are air powered vacuum pumps at harbor freight pretty cheap. You could use an air tank for oil extraction duties, and the VP to build vacuum.

Mxfrank · #5 03-18-2018, 11:21 AM

Sure, you can buy a vacuum operated vacuum pump and a cannister. By the time you're done you'll have spent more than the cost of a decent topsider, with no advantage.

leathermang · #6 03-18-2018, 11:36 AM

Quote:

Originally Posted by Mxfrank

Sure, you can buy a vacuum operated vacuum pump and a cannister. By the time you're done you'll have spent more than the cost of a decent topsider, with no advantage.

The Harbor Freight one comes with half a dozen adapters.... many people have all sorts of things which might be easier pulling the oil out from the top... although I do not really like that method it is handy some times....
I don't know that the topsider will work on those other pieces of equipment...

sixto · #7 03-18-2018, 12:01 PM

Maybe you can use the intake side of your compressor. Does it have an air filter? Make sure the collection can is deep enough that the compressor doesn’t ingest oil. Make sure the collection can is rigid enough to withstand the vacuum.

Sixto
98 E320s sedan and wagon

barry12345 · #8 03-18-2018, 04:26 PM

Old refrigerator compressor might do fine. They are small and not too heavy for a long period of time now. Plus a free good used one should be out there with little issue to obtain.

Also they can be used as a very light volume compressor. Many articles about hooking them up to a pressure tank exist. If still good they are also pretty durable.

Personally I would hook them up to a tank. Charge the tank with a good vacuum. Shut the tank valve off. Fasten my extractor hose and insert it down the dipstick tube.

Open the valve and the oil should extract pretty fast. Just an old propane tank would do it. No safety risk because even if the tank imploded from the vacuum it would just fold in. As you where pulling it down with the vacuum.

My instinct is the tanks are available free as well. Plus rugged enough. Close the valve and put it upside down on a bench after it has gotten the oil out. Then let it drain through the extraction hose into a disposable container.

This will be slow but as long as your disposal container is larger than the engines oil capacity you should not have to babysit it. Or just screw a larger drain hose on. To increase the drain rate somewhat.

I would just remove the original propane tank valve and construct a ninety degree turn to a gate valve. Also I would use a thin walled piece of steel tube as a wand to insert into the dipstick tube on any car that had a straight dipstick tube.

Plastic vinyl tubing might collapse under the high vacuum plus that internal cross sectional area is much larger than using thick walled vinyl plastic tubing. Of the same outside diameter.

Perhaps almost doubling the extraction rate in the process. With little adaption for differant dip tube sizes. This is also durable enough to last several lifetimes of use. For all brands of cars.

I also can see no reason it could not also be used to vacuum bleed the brake system when changing the brake fluid. The easier it is to do the more likely it will get done. Although on higher tech brake systems I would check first to see if it were usable on them .

Or you change a brake line or caliper. Using this the master cylinder if old does not get damaged by stroking it into unused bore areas. If foot bleeding and you do not need a helper to do that as well..

NZScott · #9 03-18-2018, 11:15 PM

When warming your cars engine to do the change, disconnect the vacuum line to the brake booster and connect it to a large tank, then once down to vacuum shut it off and hook the hose on etc...would be interested to know how well that works anyway

leathermang · #10 03-18-2018, 11:24 PM

Refrigerator compressors are a CLOSED LOOP system...just like our Cars...
the compressor Depends on the recirculated OIL to keep it lubricated....
so don't spend any time fixing up one ...

ah-kay · #11 03-19-2018, 12:27 AM

What is wrong with using a 12V pump? I rigged up a system for less than $40 from HF. Why screw around with vacuum?

vstech · #12 03-19-2018, 06:46 AM

Quote:

Originally Posted by leathermang

Refrigerator compressors are a CLOSED LOOP system...just like our Cars...
the compressor Depends on the recirculated OIL to keep it lubricated....
so don't spend any time fixing up one ...

This is true, but when plumbed for air or vacuum use, the crankcase oil loss is minimal. I have seen them in use for years with no oil loss.

Refrigerant dissolves the oil, and it moves with the charge. Nitrogen and air don't.
And when used for vacuum, the gas velocity is so small that very little oil moves.

leathermang · #13 03-19-2018, 07:59 AM

Quote:

Originally Posted by vstech

This is true, but when plumbed for air or vacuum use, the crankcase oil loss is minimal. I have seen them in use for years with no oil loss. Refrigerant dissolves the oil, and it moves with the charge. Nitrogen and air don't. And when used for vacuum, the gas velocity is so small that very little oil moves.

I think you should provide a line drawing showing an effective way to plumb that....
I am sure it is possible.... but maintain that much better solutions are available for the same money or time expenditure....

Since the vacuum in these cases is being used to pull ambient air... with moisture in it... it seems like the moisture will be getting to the vacuum pump oil... with the associated acid forming potential...

torsionbar · #14 03-19-2018, 11:10 AM

There are purpose built vacuum pumps available inexpensively. Search on "AC vacuum pump". They are used to draw a vacuum in the air conditioning system in preparation for charging. A 1/3 hp pump can be had for under $100. They come with threaded hose fittings, so it should be quite simple to attach it to your oil extractor.

vstech · #15 03-19-2018, 12:14 PM

Quote:

Originally Posted by leathermang

I think you should provide a line drawing showing an effective way to plumb that....
I am sure it is possible.... but maintain that much better solutions are available for the same money or time expenditure....

Since the vacuum in these cases is being used to pull ambient air... with moisture in it... it seems like the moisture will be getting to the vacuum pump oil... with the associated acid forming potential...

Too true.
I wouldn't want to do it for a.c. work, or anything sensitive, but for oil extraction, or vacuum controls and such, it would work if you had one laying around.

I certainly wouldn't buy a refrigerator to gut it and make a vacuum pump.