Husky 1/2" impact croaked

[someotherguy]

...and not the way you'd think. It seems to still work, except the moment you hook air up to it, it fires up like you've got the trigger pulled full time. Trigger moves, and I've knocked out the roll pin to expose the rod ("valve stem") behind the trigger, and pressing under it with a punch does seem to make some movement on the mechanism inside the tool. I've oiled, re-oiled, messed with it for too long and it hasn't changed.

This is the Husky "Pro" 550 (model HSTC4140) I bought for the shop around 12 years ago and it's truly not been used enough that I'd expect problems out of it.

I don't see anything in the parts diagram behind the valve stem (#34) so I'm confused as to what is moving back there when I press on it. There's a tiny O ring (#33) that sits in the middle of the valve stem, and while I guess it could be worn and cause problems, there's no way this one tiny O ring is meant to hold back all the pressure? Is it? I've never repaired an air impact before.

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Richard

 

[Komet]

I'm suspicious that part #39 has failed, or part #40 can't hold it back anymore.

 

[GoToGuy]

You have to drop out the handle parts where the air feeds. Some thing is off, or out alignment, or broke. It's whatever is regulated in the Handle.

 

[someotherguy]

Thanks for the input - like I said I haven't had to fix one of these before. Parts don't seem to be available at first glance, as these are the Taiwan/China-made Husky tools, where the earlier Japanese models do have kits available for them. I'll dig into it further and if it's just a seal, spring, or something I may try to dig some up.

Richard

 

[Erik the Awful]

That's most likely a rebadged Mac Tools impact.

 

[Schurkey]

Parts don't seem to be available at first glance, as these are the Taiwan/China-made Husky tools

Yup. My usual source for repair parts doesn't have parts available for that model.

Husky H4140

Husky H4140 – 1/2" Drive Air Impact Wrench – buy now, order replacement parts, browse accessories, view product details and warranty info, and download documentation.

powertoolrepair.com

That's most likely a rebadged Mac Tools impact.

Mac Tools doesn't make impact wrenches, or any other air tools that I know of. The source their stuff from outside suppliers, who custom-label the product with a Mac logo. Then Mac jacks-up the price by a huge amount.

Proto, AirCat, SP Air, and I-R have supplied impact wrenches and other tools to Mac, and there's probably other suppliers as well. I have a Mac-branded "AW160" 3/8 impact which was actually made by SP Air, as best I can tell from the replacement parts. My Mac die grinder is also an SP Air product. SP Air is a Made-in-Japan line of quality tools. I have Mac 3/8 and 1/2 inch air drills, made by Viking in the USA. Went nuts trying to find the reverse-thread chuck screws to fit them--Viking has discontinued those air drills and there's no more screws available. Had to install a (weak?) stainless steel screw in the 1/2"; I don't expect that to hold up very long but it's what I can find.

Point is, it's possible that the Husky and the Mac are re-badged from some actual manufacturer in the Far East. Which then means that--if you have all friggin' day to devote to research--you might find another air tool that uses the same parts for the trigger assembly, or perhaps the entire tool, by semi-randomly selecting other (Mac?) 1/2" air impact tools and looking at their repair part diagrams. I tried that with the chuck screws, and eventually found something from another manufacturer that fit.

 

[Erik the Awful]

Mac Tools is the overarching tool company over a handful of other brands. I should have remembered that I-R was one of Mac's suppliers. I had a Mac twin-hammer impact back in the day, and when it got stolen and I had to replace it I discovered the I-R was the exact same impact for about the same price.

 

[someotherguy]

It's #37 and #38, both described as "washers" - I knocked out the lower roll pin and pulled the air inlet, valve, etc. and found broken and compacted crud where there used to be washers. They're larger than O-rings (smaller I.D.) but can't find any specs on them anywhere. Can't find the parts, either. Husky doesn't service them (too old, discontinued) and so far can't find the parts online. There's a company selling some parts but not for this model; apparently they've got some for the older (Japanese-built) units.

With the bits of washers dug out it actually kind of works, but unsurprisingly has a massive air leak out of the lower roll pin.

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I'm "close" yet so far away. Ready to just buy a different brand to replace it with.

Richard

 

[someotherguy]

Said fck it and bought a used older model Husky H4140 off ebay for $50 shipped. Looks to be in really good condition. The H4140 is made in Japan instead of Taiwan, and some parts are still available for it, for the moment.. I think what made me go ahead and choose a used Husky is I don't need a 1/2" impact very often these days, so I didn't want to cash up $150-$200 for a "good" brand new one that will still be made in China. Plus, I've got an older Japan-made 3/8" Husky impact that I actually used to snug the lug nuts with and man it's still got plenty of power. I'll keep the HSTC4140 around in case I ever do find suitable seals for it, and because I'm a dumbass packrat.

EDIT nevermind the seller just refunded me saying he "didn't realize the item was no longer in stock" W T F

Richard

 

[GoToGuy]

So by the pattern on the washer, it appears that it was under the star shape? And s does that star shaped with shaft , get moved or rocked by trigger action?
Most mass produced economy tools use off the shelf standardized small parts and seals gaskets, readily available and cheap in mass quantities.
With the bits you have left and the part it fits you should be able to use your caliper to get the size, and refer to an o ring or washer gasket chart for exact standard size.
I have had to do this many times as antique and classic have few off the shelf parts.