I found a long forgotten heavy-duty impact wrench that takes the bigger-than-usual sockets (3/4" ?).
Anyway, the wrench was seized from rust. I disassembled it and left the parts submerged in diesel overnight. The next day I used a wire brush and sand paper to remove any remaining rust and re-assembled it.
Voila! It’s working…but it has very little power. It is weaker than even my regular-sized impact wrenches. I was wondering if the air line pressure is not enough. I have a heavy duty air compressor with a 500lt receiver and the pressure is set at about 6 bar. Is that enough for a heavy duty impact wrench? Or maybe did I do something wrong when re-assembying?
The Snap-on tools catalog recommends 90 psi (620 kPa, 6.2 bar) for all of its air impact wrenches, so it sounds like you should have enough pressure. Another consideration is air flow. The 3/4" drive models have from 4 to 7 CFM (cubic feet per minute) air consumption while working (in comparison, the 1/2" drive models use 2 to 4 CFM). A too small line or hose, or a restriction therein, could be a problem.
I wonder if sanding certain surfaces might have affected its ability to “hold” air. Assembly error is always a possibility. The only other thing I’m aware of is the condition and orientation of the vanes, if it has them.*
*The one air tool that I’ve disassembled had four plastic vanes that were what drove the mechanism. They had to be smooth on the surface that touched the bore of the air chamber, they had to slip easily in their slots, and they had to be oriented in a certain direction.
Mr. Goob
Remarkably, there are no o-rings in the air motor compartment. This illustration shows an impact wrench that is very similar in construction to mine. The motor housing is part J which is sealed by the front and rear plates (parts G and N). There’s nothing between the housing and the plates. Just metal on metal.
Gary T
I guess the problem is not enough air flow then. I used a spiral air hose similar to this (mine has quick couplers). This hose is really thin. I will try to use the wrench tomorrow with a standard rubber hose.
I guess the vanes are part L in the illustration. They slide in and out without any problem.
