Leaky Dash Tractor valve?

Ahh..fun times.

 

Next time I will get the kit for sure....

 

Well that fixed it, but I had a leaky hose next (constant leak) so I had to change out one of the 'fittings' - but all is well now....

 

Ok...so now I have no air leaking from the face of the valve. But my tanks were still going down faster than I liked, so I continued looking for additional air leaks...

1. Interlock switch leaks air when set to DISENGAGE. It's not much and not the hoses, its coming from where the switch lever (front) is. Not sure I can do anything but replace that switch.

2. When I replaced the entire valve unit, I had some issues removing one of the 'quick-couplings' and think I damaged it...soapy water shows air leaks from the elbow itself where it meets brass and screws into the valve assembly. The brass is not leaking at the valve, but where the plastic part of the quick disconnect starts... Dealers here do NOT carry these. So I figured I would get the following:

Right angle 3/8COMP X 1/4MPT fitting. Looks and fits like it should. Problem is, no matter how hard I try, I cannot get the air line to NOT leak at the compression fitting. The MPT side is tight and perfect. I have gone through 3 ferrules and even swapped out this elbow for another.

What the #### am I doing wrong?

Slide the nut down the plastic tube.
Slide the compression ring on the tube.
Shove the tube into the fitting, pushing the compress ring into the connection.
While holding pressure on the hose into the fitting, then bring up the collar and tighten.

Unless I need to crank this to like 100 ft LBs, I dont know what else I can do and its really getting frustrating. This should be simpler. I am guessing the plastic tube doesn't crush like a copper tube+collar would, but this is what the dealer told me to use, they use since they do not carry the quick disconnect ones.

HELP!

Here is an example (only) of the style of fitting I have. Disregard the size listed:



EDIT: I was thinking about this...the dealer SHOWED me copper units, but I am wondering if I really need this instead:

DOT Nylon Tube Compression fitting:
http://www.fastenal.com/web/products/detail.ex?sku=440822-131280&ucst=t

 

Ok..so are you guys saying that all I need is the connector I have, but with a little sleeve for the tube? - Copper is OK with this tube?

I am not sure here, after researching it, it seems like I need DOT air line fittings or something. But if this tube is all I need to make things work, I am sure my local ACE hardware should carry that..even if I have to buy it from another part to make my own parts up..