Gas leaking ito liner?

[cliveje]

Hi,

I have an old Hobart Handler 120 - a 90amp welder that gets good comments (the model before Miller redesigned it).

When the trigger is pulled, not only does gas come out of the tip, but it is coming out of the output wire guide, i.e. where the wire goes after the roller. Is this normal?

With the gun disconnecet from the welder, if I blow into the liner at the feed end, air does come out of the orifices where the gas feeds into the 'plug' , so it is not a question of the plug O rings not sealing - it is leaking from inside the plug into the liner. As I say, I don't know if this is normal. The liner is a coiled spring in excellent condition. The parts list does not show any seal between the liner and the output wire guide.

Thanks,
Clive.

 

[fingers99]

My guess -- nothing more -- is that the gas line is punctured.

 

[malcolm]

I'd agree the gas line probably has a hole. Maybe a bit of spatter has burned through it. Ought to be easy enough to feed a replacement gas line through the torch cord, or even removing the gas line, repairing with tape, then re-fitting. Should be no more difficult than replacing the wire liner (which is a regular service job and will transform the welder if it hasn't been done recently).

 

[rtbcomp]

If you're going to replace the gas line, attach the new one to the old one so it pulls through when you remove the old one.

 

[cliveje]

Thanks guys - the manual doesn't cover changing the tube, or list it as a separate part, so I'll see if I can remove rubber sleeve where chord connects to socket to see if I can access the joint. After all, it will have to be a new gun otherwise.

Clive.

p.s. liner seems good - I run on very little roller tension and have smooth positive feed.

 

[fingers99]

I'd be surprised if you can't buy the tube off the shelf somewhere as something else.

 

[cliveje]

Just looked, and the gas tube in the cord is concentric with the liner, so it looks lke the liner is to blame.

Won't all liners leak somewhat whenever the cord is not straight?

Clive.

 

[fingers99]

Long time since I pulled a MIG to bits, but I'm sure my liner and gas tube were completely separate.

Could it be that the ones for that torch are supposed to have an outer layer which would serve a similar function to a teflon one, making it gas tight?

 

[shenion]

Sounds like a Tweco type gun (Lincoln and Tweco are very similar). The lead is coaxial: liner, gas tube then wrapped in the power lead.

There is an o-ring right where the liner end fits to the end of the plug. The liner could be pulled out a little.

 

[Luke]

I had a similar problem with my old torch.

The liner and gas tube are seperate items, but are concentric.

a poor tube clamp meant that pushing the liner through had pulled the hose from the torch.

 

[cliveje]

Does the liner on concentric cords have a sheath?

The first few inches on mine had a cellophane like wrapping. I'm now concerned that this has come off the rest of the liner and bunched up inside the cord as the liner is very difficult to pull and I have not been able to remove more than about 1/2 its length.

Thanks,
Clive.

 

[cliveje]

Update ...

The liner did have a sheath of some sort of cellophane that had deteriorated, come off and bunched up in the gas tube, effectively blocking it.

It took a few hours of patience (and not so patient) to hook it all out with welding wire. I will use compressed air to ensure everything is clear. I have resheathed the liner with electrical tape, so it should now work as inteneded.

Clive.