I have a Napa 1/2" drive magnesium impact wrench that I use daily, that is about six years old. After a couple of years, it started to want to run without the trigger pulled... It has gotten worse over time. Its always been oiled regulary. and not too abused. I totally disassembled it and cleaned everything, and didnt find the problem. Its actually worse when I oil it. Im so sick of it im using an old backup cheap impact. Am I overlooking something? Im guessing in the trigger mechanism?
Fixing an impact wrench
- Thread starter Haveblue
- Start date
Dusty61
Well-known member
Sounds like there is something keeping the air valve stuck open or an air seal is ripped letting it leak. Check all the O rings
kams1973
ALLIANCE MEMBER
What kind and how much oil are you using? Some oils end up sticky or tacky in an impact.
RKSpeed
Well-known member
Had same problem with an impact of mine. Found the coil spring holding the valve shut was weak. Stretched the spring out some and seemed to fix the problem.
emeraldcoupe
Well-known member
bad inlet bushing. what model is the impact?
if it runs on its own, then its in the trigger before it gets to the rotor and vanes. take apart the trigger, depending on the style, youll want to clean it up extremely good, possibly using some emery paper on anything that slides if it looks dark or slightly rusted. make sure o-rings are good, and make sure that springs that are supposed to push the valve shut are in place.
emeraldcoupe
Well-known member
ex-x-fire
Well-known member
Post a picture of it, is a IR knock off? Mine does that once in a while, I have to remove the inlet bushing, then the spring & air valve. The air valve is what has the o ring. The right lower corner of the picture shows a pin shaped part, right below it is the valve, that's what has the o ring.
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emeraldcoupe
Well-known member
here you go. the inlet bushing is leaking due to being cracked or chunks missing. this is the cause of run on 90% of the time. will most likely be #40 in the diagram.
http://www.powertoolrepairohio.com/pages.php?pageid=14&breakid=551
http://www.powertoolrepairohio.com/pages.php?pageid=14&breakid=551
ex-x-fire
Well-known member
Something in the #"s 31,3233,34 ,39,40 area. There should be an o ring there.
Thanks! I didnt pull the inlet apart. Your diagram reminded me that I still have the manual with that in it! That will make it easy if I have to order that bushing. I can make a copy of it, circle the part I need, and fax it. Ill have em call the tech line, and find out whos got parts. if its just an o-ring, we have a ton of sizes, so that would be easy!
NHBandit
Well-known member
Well this thread made me go out in the garage and take inventory of all the old air tools in my "junk drawer" in my old MAC box. I got 3 1/2" drive impact guns working, 1 3/8" air ratchet, 1 1/4" air ratchet, an air drill, air chisel and a sand blasting gun working great. These are all in addition to my "good" air tools that I keep in the toolbox I use everyday. Also still have half a drawer full of "fix it someday" air tools.. Yeah I have too much stuff.
Funny, I was talking tools with the boss saturday, and asked him if the tool rep could get parts, or fix it for me. I told him you guys at GJ said it was an inlet bushing problem..he said, "yep" grabbed my impact, pulled apart the inlet, looked it all over. He removed the steel bushing #40 and looked at #32, (was ok) he put it back together without # 40, and problem solved!?!? It works great now! He said his impacts dont use the steel bushing, and they are fine without them. 
emeraldcoupe
Well-known member
Funny, I was talking tools with the boss saturday, and asked him if the tool rep could get parts, or fix it for me. I told him you guys at GJ said it was an inlet bushing problem..he said, "yep" grabbed my impact, pulled apart the inlet, looked it all over. He removed the steel bushing #40 and looked at #32, (was ok) he put it back together without # 40, and problem solved!?!? It works great now! He said his impacts dont use the steel bushing, and they are fine without them.
told ya
. glad you got it fixed.Thanks for the advice emeraldcoupe! A guy gets so busy working on customers vehicles, sometimes you gotta take a break, and fix your own stuff! Since my problem seems to be solved, id love to see this turn into a thread about rebuilding air tools. I invite everyone to tell what you have done to keep your air tools running! Post em up! 
ex-x-fire
Well-known member
On those old IR 231 & 244s, the bolts that the 2 main parts together sometimes loosen up, causing a big drop off in power.