Millermatic 150 gas won't flow?

[tomget]

How do I trouble shoot the gas not flowing to the tip of my Millermatic 150. I've got plenty of gas in the cylinder and I've turned the flow up and down..and I can see the "flow gauge" needle bump(tiny movement) for a second when I depress the trigger but it doesn't show a flow rate like it once did, and wire is coming out etc..but zero cloaking gas? I can hear a clicking in the machine when I pull the trigger..and expect the gas..but none coming out.

Is it the cylinder gas gauge assembly? Or some part of it. Or is it the liner or something in inside the machine. Wire comes out fine, just no gas.

Pretty new to welding..appreciate your help.

Tom

[Cgotto6]

I would disassemble and check out the regulator.

[Meltedmetal]

Disconnect the gas hose at the machine and check for gas flow from the hose. If you have it there, the problem is in the machine, if not work your way back to the cylinder.---Meltedmetal

[cruizer]

9 times out of 10, its your mig gun end not fully inserted into the machine drive connection, the other 1% its debris stuffed in the inlet screen where your gas hose connects

[tomget]

Thanks for all the suggestions. I'll give them a try.

Tom

[tomget]

I disconnected the black rubber gas hose where it attaches up front by the wire roller and goes into the welding cable, and when I depress the trigger I get a momentary puff of gas and then just a tiny flow of gas thereafter.

I went to the back of the machine and get the same puff of gas coming out of the gas valve and then just a tiny amount of gas..but when I check gas coming into the valve it seems to be a constant flow.

I'm guessing the Miller 218422(the part I've found on line??) gas valve needs replacing? Does that seem correct?

Tom

[Meltedmetal]

Look at Cruizer's post above. Find the screen on the inlet to the machine I guess and clean it first before you buy anything.---Meltedmetal

[tomget]

Look at Cruizer's post above. Find the screen on the inlet to the machine I guess and clean it first before you buy anything.---Meltedmetal

OK will check that.

I've looked everywhere but don't see anything on the machine that looks like an "inlet screen"..The hose from the tank fastens into the valve at the back of the machine and nothing there. I've separated the valve itself into the electric solenoid being one part and the plastic housing that allows the gas to flow, but no screen there.

Where would the screen be? I can't find it.

Thx

[Meltedmetal]

You have verified that the gas is flowing to the machine with the hose disconnected?
The screen should be inside the inlet to the solenoid valve body I would guess. It will be very small if that's where it is. What do you see if you look into the inlet?
Can you manually activate the valve with it disassembled? Does the gas flow?---Meltedmetal

[cruizer]

Remove the gas hose at rear of machine then look in at the gas soliniod. There may be an inlet screen in there. This screen likes to plug up. Thus burst of gas then slows down to nothing.

[JSFAB]

Since you are "pretty new to welding", how do you know there is a problem with your gas flow? Have you actually welded with it, and have symptoms of no shielding gas in the weld?

The "puff" you are talking about is normal, when the trigger is first pressed you are releasing the pressure built up behind the valve up to the limit of the flowmeter/regulator. Once the trigger is pressed for a second or two, there is essentially no pressure in the line, since it is an open, free-flowing line. Assuming you are running 15 - 20 CFH, it is pretty hard to feel if the gas is flowing through the diffuser, especially for an inexperienced person. It will NOT feel like it does coming out of the hose, or an air compressor line. It would feel like you opened your mouth very wide, and gently/softly breathed out.

[cruizer]

Thats true too, I use my ear against the nozzle to hear the air flow. If you have a actual flow meter you can see the little ball rising. when you hit the trigger.


Duh, should have though of this first....

The question should have been, "I have lots of porosity in the weld" No gas?

[tomget]

Remove the gas hose at rear of machine then look in at the gas soliniod. There may be an inlet screen in there. This screen likes to plug up. Thus burst of gas then slows down to nothing.

As i mentioned earlier i did remove the gas hose at the rear..no screen anywhere that I see and yes the gas flows freely from the hose from the tank.
But when it goes through the valve it only makes a single burst of gas and then slows to a trickle or is not flowing at all.

I bought this machine new and have the Miller owner's manual with all the schematics. It doesn't indicate a screen of any kind in that area.
Millermatic 150 and GA-17c gun June 1993..is the date on the manual.

Maybe the newer machines have a screen. I don't know. All I have with this is an electric solenoid that pulls or pushes on a rubber looking round diaphragm that then allows gas to proceed or stop passing through the gas valve. Its all pretty open and there's no screens or moving parts other than the round diaphragm.

The gas flows into the valve just fine, but not out. So it could be a bad signal from the trigger itself or something with the diaphragm that is failing to keep it in the open position. Other than that I can't think of what it might be.

[tomget]

BTW I have the gas inlet plastic housing separated from the solenoid..its just connected with two small fasteners..and I can put the gas inlet to me mouth and blow into it and the air passes through freely with no restriction. So to me..that means there is "no screen".

[cruizer]

Actually, everything is working just fine, have you welded with it?