miller 251 gas issue

stupiddumbidiot · Jul 30, 2022

im having a problem with a gas leak where it seems to be leaking by the wire feeder . i swapped out the o rings thinking maybe it was getting out through there but it seems to be coming from this portion of the wire feeder. sorry i dont have the words. but ive highlighted it in this picture i found on the interwebs. im not losing gas pressure though the tank or anything like that. a tiny bit of the gas will flow through the gun (where it meant to) but you can hear it all escaping and you can feel it coming out of that hole that is circled on the picture. anyone experienced something like this ///anyone have any bright ideas on how to fix this. this week this has happened to me twice the first time it was the o rings and that solved it for half an hour than it went back to leaking . it does not seem to be leaking through the o rings this time it seems to be dumping out the back end where the wire feeds.

sorry if this is dumb im a stupid newb and im using someone elses machine and i just want to fix this goddamn thing so i can go on with my life. anything helps
View attachment Screen Shot 2022-07-29 at 8.38.22 PM.jpg

Oscar · Jul 30, 2022

That part you circled is the cover for the liner. Release the pressure on the black knob, pull out the whole back end connector and you should see hex or flats to put a wrench and snug it down. I don't see how else it can escape from back there unless it was loose.

G-ManBart · Jul 30, 2022

It could be a blockage downstream (somewhere towards the gun) that is causing the gas to escape out the back end of the liner. I would pull the torch off the machine, pull the liner and blow compressed air through everything reassemble and see what happens. If there's too much pressure it would easily push past the o-rings. If you want to be even more thorough, coil the liner into a circle and soak it in some acetone for half an hour before blowing it out with compressed air.

stupiddumbidiot · Jul 30, 2022

View attachment Screen Shot 2022-07-30 at 4.33.15 PM.png View attachment Screen Shot 2022-07-30 at 4.33.10 PM.png
so i pulled off back end connector and found that the the liner was all ****ed up and i sprayed some soapy water to see where it was leaking from and its shooting out the rear end (where this this is all ****ed up) . pretty sure just replacing the liner would solve my issues. but id like to get some more professional opinions so fellas you think thatll solve my issues. also how does this happen? common issue?

swainj · Jul 31, 2022

Missing the brass piece of the liner with the oring to seal the gas and prevent it from flowing back where you circled. Replace liner properly and move on

Oscar · Jul 31, 2022

Yup, it's supposed to look something like this:

Dan · Jul 31, 2022

That liner is for the older M 25 gun. Based on what I am seeing of the backend, the gun assembly being discussed is a new MDX model which has a different liner set up.

G-ManBart · Jul 31, 2022

That does look like the newer MDX gun and it should have a cone-shaped brass nose where the threaded part is showing in his pics.

lpjenks · Jul 7, 2023

did you ever figure out the problem? i am too having same problem.

Dan · Jul 7, 2023

Are either of the two O rings on the power pin end of the gun lead chewed up or missing ?

miller 251 gas issue

Top Contributors this Month

Recommended Communities