CP 714 air hammer died

[2ndGearRubber]

I was wailing on knuckle earlier today and my cp714 decided to stop. Its currently spitting out air at a low hiss, very little piston movement. Bit is not broken, tried 2 different chucks and no chuck at all just holding the bit on the ground.

This happened once before, gave it to my indy tool guy. He said his service guy said the trigger had some sort of issue. Well it's a week before his next visit, any one have knowledge on trouble shooting an air hammer?

 

[MattT]

I was wailing on knuckle earlier today and my cp714 decided to stop. Its currently spitting out air at a low hiss, very little piston movement. Bit is not broken, tried 2 different chucks and no chuck at all just holding the bit on the ground.

Might be a piece of trash binding the the piston up. It should rattle freely when you shake the gun.

Anyways just tear the gun down and inspect everything. With it just quitting it's probably trash in the piston or valve. And once you've the valve and everything out you can test the trigger by hooking the air back up. Should get a good blast of air when the trigger is pulled.

Download the schematic from this link. Looks like there's a locking pin that'll need removed before you unscrew the barrel.

http://www.repairtoolparts.com/chicago-pneumatic-parts/chicago-pneumatic-cp714-parts-list

 

[emeraldcoupe]

make sure the barrel is TIGHT. if it loosens up it won't work.

 

[2ndGearRubber]

Okay, got it mostly apart. Trigger and trigger pin clean, inlet hose/fittings and regulator and respective o-rings all good. Air valve looks good, not in two pieces anyways. With the gun off, I can rattle the piston around, it seems to fully travel and moves freely. I give it the old "knock knock" on the work bench, didn't help.

I tore the gasket for the inlet housing (ordering a new one), and when assembled with the leaking gasket it pukes air pretty aggressively out of it. I can't even stop the flow with my finger when the trigger is half depressed. This tells me my problem is definitely on the exhaust side, assuming a restriction/gunk of some sort. I took the exhaust cap off, the very end of the exhaust ports look okay.


I'll add a picture of where I am tomorrow. I'm ready to tear down the barrel itself, but am stuck on how to do it. The barrel is plenty tight, appears to be kept from spinning by the locking pin, which cannot be hammered in further for removal. I'm assuming I need to extract that pin and then try to twist the barrel apart. I have to guess CP uses a locking compound of some sort as well, since I couldn't really budge the barrel in either direction. If anyone has taken one of these apart before, I'd be grateful for some insight.

Would it be foolish to try and blast it with some brake-clean and see if any junk come out? Mainly hoping it won't push any debris into an even more obscured area.


Part 34 is the pin in question, the diagram is a bit generic.

 

[Skin]

On the diagram there are some valves behind the piston. If they get stuck you'll get your symptom also. Particularly part 24.

 

[MattT]

I'll add a picture of where I am tomorrow. I'm ready to tear down the barrel itself, but am stuck on how to do it. The barrel is plenty tight, appears to be kept from spinning by the locking pin, which cannot be hammered in further for removal. I'm assuming I need to extract that pin and then try to twist the barrel apart. I have to guess CP uses a locking compound of some sort as well, since I couldn't really budge the barrel in either direction. If anyone has taken one of these apart before, I'd be grateful for some insight.

Try pulling the pin out with a strong magnet first. If that doesn't work smacking the gun down on the edge of a bench will probably knock it out. You might have to rotate the barrel slightly to take pressure off of the pin first.

Pipe vise is the best way I've found of holding the barrel. Or a bench vise with those pipe jaw things under the main jaws might work.

Would it be foolish to try and blast it with some brake-clean and see if any junk come out? Mainly hoping it won't push any debris into an even more obscured area.

I wouldn't risk it. There's definitely o rings in there that the solvent may attack and the valve might not be metal. I guess you've already tried oiling the heck out of it?

 

[2ndGearRubber]

Pin in question below, I didn't get a chance to mess with it at all today.

 

[Skin]

Pin is probably interference fit. If it were mine i'd drill a small hole into it deep enough for an easy out and try to pull it out that way.

 

[MattT]

Pin is probably interference fit.

No it ain't. The only ways that pin is an interference fit is a manufacturing defect or corrosion.

 

[2ndGearRubber]

Well, the pin is quite stuck. I poured air tool oil through the exhaust ports, hopefully that'll fix it. Gaskets should be here monday, so if it is still broken I guess I'll send it to the re-builder.

 

[Skin]

No it ain't. The only ways that pin is an interference fit is a manufacturing defect or corrosion.

Cant be that loose. Its an air hammer after all. If it was just sitting in there it would rattle out in no time.

 

[2ndGearRubber]

Agreed, however I can't knock it out. No way to grip with pliers, if I try to rotate the barrel any harder I'm worried I will damage the tool body. I tried knocking it up with a punch, the pin is slightly dented, no movement. Tried knocking it downwards, put a witness mark on the pin, no movement. If I knew the removal procedure for sure, and ideally had another pin, I might be more inclined to mess with it. Drilling it out then replacing seems like the easiest option.


I think it was $50 for the pneumatic guy to look at it last time, and fix it. I should know Wednesday if the oil soaking and cleaning did anything once my gaskets show up.

 

[Skin]

Like I said it it were mine i'd drill a 2-3mm hole and use a small easy out. Just to give you something to pull on.

 

[2ndGearRubber]

Perhaps I'll try that on monday if I have a spot between cars.