Hello Everyone
FYI:
Most of us need a vacuum pump at one time or another.
Here is an alternative you may consider.
Ever see a refrigerator, freezer or window A/C unit setting out to the trash.
Each one of these has a compressor/vacuum pump.
Common sense must be used when getting one out for your use.
The static pressure can be 140 psi and if cut or punctured blows a dangerous to breathe white cloud.
The total charge is only a few ounces.
An A/C compressor has input = suction and output = pressure pipe.
When you junk the box, you are left with a small air compressor and vacuum pump, depending upon which pipe you connect to.

The only danger to your car; is that it can suck much harder than the cars vacuum pump, a gauge and bleed valve are good to have in the line to your car.
I use the pump attached to a (recycled 30 LB refrigerant tank) vacuum tank, then attach the tank to the car, even a bad leak takes time to use up that much reserve.
The average is two of three compressors are ok, when used this way, durability life is 3-5 years.

Ok; here comes the legal stuff.
You must have a licensed recovery person salvage the refrigerant.
It is illegal to dump the charge to atmosphere, the fines are quite large.
If you choose to attempt this; you assume full responsibility for your own actions.
I have written this as an FYI, not a technical how to.
By reading this, you acknowledge that you are smarter than a gerbil and a legal adult, results may vary in alaska and Hawaii, smiles are dangerous to depression and you are responsible for what you do, all warranties void on Mars.

__________________
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Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
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1985 300SD
1983 300D
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Great tip!

If the refrigerant is used to lube the pump, what keeps it from killing itself after a few hours of use?

82-300td, Very sneaky way of saying that these are closed loop systems which depend on the circulation of the oil with the refrigerant.... also , the amount of air when used as a compressor is tiny compared to any regular compressor.... if one is really wanting to do this then you could install an automatic oiler on the intake ( like is used for air tools ) and make a drain on the output side to keep the level correct.
But for people really wanting to do this with home left overs... a small lawnmower engine run by a used washing machine motor can do a better job and last a long time.... because that system retains the original oiling mechanism.
Now for you ( ARGH , ARGH, Tim the TOOL MAN ) power hungry guys.... a VW engine can be run just fine on two cylinders... which leaves two cylinders which can be modified ( the valves ) to give a very compact, powerful portable compressor .... in fact ... a bolt on head conversion was available commercially for this trick...

Hello Everyone
Other ideas.
A Chevy 350 makes a very nice compressor, when attached through a flex coupler to a 258 straight six.
ARGH ARGH more POWER more POWER RRRReal POWER.

I never lube the refrigerator compressor, after three to five years, just scrap it and make another.

Automotive A/C system dead?
Automotive A/C compressor workers the same.
Route the suction and pressure side to the air filter housing to keep the system from sucking road trash by accident.
Connect to the side you need.
Jumper the A/C compressor from battery positive to battery negative through a switch.

A better idea.. if you are going to run an engine with another engine ... Turn a straight 6 into a combination of air compressor ( with the back five cylinders... and the front hole used to run a power hammer....
For more on this type thing... check out Keenjunk.com

I think I see where this is going...........

Wes

We might scare someone?

Hello Everyone
You can always borrow a gasser and run a T tap to the intake manifold vacuum port.
But that is cheating.
Fifteen years ago; I watched a neighbor try to use his vacuum cleaner, he had a perfectly good gasser parked five feet from it, after three days of laughter, I took a 20 foot coil of vacuum line and showed him how to cheat. LOL

I have an old air hose set up that uses one the cylinders from a gasser engine as the compressor. You unscrew one of the spark plugs and screw in the adapter into the spark plug hole, hook up the hose and you have a hose to put air in your tires or hook up a pressure tank to collect the compressed air and use your engine as a cheap air compressor. The air line even has an in-line air pressure gauge. Works great but don't smoke around this contraption as there is gasoline in the air mixture.

__________________
DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012

Ah, the old exploding tires trick...

Wait 'til firestone and Ford find out about this!

Wes

Exploding tires...
I had an uncle that regularly used a propane tank to inflate ag tires.... I am not that brave....

Don't try it on a dirt bike!

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__________________
DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012

I have 2 refregerator compressors that I use quite a bit. One is set up with an automatic on/off (120 psi.) with an unloader valve, and a 1 gal. tank. The other I use for vaccume with a 20 lb freon tank as a reservor. I use my mighty vac or an airplane altimiter (threaded port on the back that goes to the static air vent) for guages. The altimiter gives you a much faster indication of what is happening when testing for a slow leak. They both have oil sumps in the bottom with sight guages. I had to add some compressor oil to one of them when I first got it. They have used virtualy no oil in 18 to 20 years. Besides being portable, I use the pressure one a lot plugged into my big air tank so I don't have to listen to my big compressor chugga-chugga.

Lou

You guys are giving me ideas...

I wonder if (after properly disposing of the old refrigerant and flushing out the system with mineral spirits and replacing the seals to convert to R134a) I could find a way to use the Benz's vacuum pump to pull a good vacuum on my truck's a/c system (or, for that matter, I suppose I could even use the truck's vacuum pump)?

Unforutnately (or fortunately?), I don't have a g@$$er to cheat with...I do like the refrigerator compressor idea, but if I could get the vacuum pump on the car to do the job, then it'll be free (instead of cheap ) to do.

I don't think the MB vacuum pump has the volume pull to clear out an A/C system in reasonable time. Besides, do you really want to risk something getting into your $$$ vacuum pump?