Air leak, need info on plastic/nylon lines and fittings

[dusterjh]

Hi All,

Still new to the M35 bobber I bought about a month ago, loving every minute of it.
Anyhow I have a pretty bad air leak coming from the gladhand fitting (my truck only has one) I'd like to replace with the plastic, polyurathane, nylon air hose I have found that people use for air ride systems etc., and I don't know which is better the poly or nylon, I've tried searching the net and this site without much luck. There a few places on the net or e-bay but not much information on fittings anyone have a good source on the net for this?
Also I believe I need the 3/8" tube size but not sure.
I'd rather replace the copper with the flexible stuff as I go through the truck.
Thanks for the advice in advance.

Oh and anyone near northeastern PA, don't know anyone around I can hook up with to enjoy this MV hobby.

Regards,
Joe
Towanda, PA

 

[Nonotagain]

A quick search of hose manufacturers yields the answer to your question.

3/8" polyurethane tubing is rated @ 147 psi @ 75 F

S p e c i f i c a t i o n s
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Temperature Range: . . .​

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-40° F to +165° F​

Vacuum Rating:. . . . . . . .​

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​

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To 28" Hg.​

Diameter Tolerances: . . .​

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1/8" - 9/16" +/- .005"
3/4" +/- .007"​

Working Pressure: . . . . .​

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​

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3 to 1 Safety Factor​

Compliance: . . . . . . . . . .NSF61, Meets UL94HB

http://www.coilhose.com/uploads/products/Page 68.pdf

3/8" nylon tubing is rated @ 220 psi @75 F.

S p e c i f i c a t i o n s
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Temperature Range: . . . . . . . . . . .​

​

​

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-60° F to +200° F​

Vacuum Rating:. . . . . . . . . . . . . . .​

​

​

​

To 28" Hg.​

Diameter Tolerances: . . . . . . . . . .​

​

​

​

0.002"; -0.004" All inch sizes;
+0.051 mm; -.1 mm All Metric sizes​

Hardness: . . . . . . . . . . . . . . . . . . .​

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​

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78 Rockwell R​

Working Pressure: . . . . . . . . . . . .​

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​

​

4 to 1 Safety Factor​

Compliance: . . . . . . . . . . . . . . . . .Meets UL94HB


http://www.coilhose.com/uploads/products/Page 69.pdf

 

[Jake0147]

I don't think I could envision myself removing good copper for nylon... Possibly replacement with nylon simply for the ease of installation, but I can't think of another good reason. That'd be my choice if I were to do so.

I think you're going to want half inch for the glad hand plumbing, but that's purely off the top of my head. I'd strongly recommend getting the compression connections, PTC stuff is quick to install but a PITA from there on out.

Your truck should have two glad hands. Where exactly is the leak? The glad hand (originally anyhow.....) was supported by hard plumbing which means that would be hard to replace with tubing. There was also a shutoff valve on each one. Once you get inside of that, it should be a straight shot with tubing of choice.

 

[dusterjh]

The truck was bobbed by the previous owner and I can see where the old line for the second gladhand is still there but disconnected and crimped off near the back of the truck. The leak is in a compression fitting where the gladhand is attached. I took it apart and didn't see any cracks etc., then re-assembled and tightened down with no better results.
I'm no plumbing expert by no means so please excuse any stupid comments

 

[Speddmon]

If it were me, I would use the copper and stay away from the poly/nylon tubing for that application. Copper may be a little more difficult to work with, but it will handle whatever extreme condition you throw at it. Plus the higher pressure poly/nylon tubing is stiff as a board on the best day, at least copper tubing is easy to bend around.

 

[dusterjh]

If I were to stick with copper, is there a special kind for automotive applications? Where can i get it?

 

[Speddmon]

just regular 3/8 or 1/2 tubing, whichever you have or want to use. Get it at the hardware store, plumbing supply house, contractors supply houses. They should sell the compression fittings at the same place as well. Copper tubing is not really hard to work with at all.

 

[Jake0147]

...the old line for the second gladhand is still there but disconnected and crimped...


That should be corrected. It should be caped, removed to a fitting where it can be plugged, removed to a fitting and then the fitting removed where it can be plugged with a standard easy to find brass pipe fitting... But crimped isn't good.

... The leak is in a compression fitting where the gladhand is attached.

It's probably either A) cracked right between the ferrule and the tube, right at the edge where you can't see it, or B) the ferrule is crushed down too far from repeated reuse and/or over tightening at some point in it's life. The solution would be (in an ideal world) to trim the tubing just behind the original ferrule, clean it up nice, add a new ferrule, and snug it back down. Of course there has to be enough tubing to "stretch" the line that far, and since copper doesn't stretch... Well the situations aren't always ideal.

I'm no plumbing expert by no means so please excuse any stupid comments

You needn't be an expert for this, just a couple of open end wrenches will be fine. Because this is not an air brake truck, you are not restricted on what fittings you use. Stuff from the hardware store is fine. If you intend to tow an air brake trailer (or if the truck had actual air over hydraulic or full air brakes) then you would be quite restricted in your fitting choices for any modifications. (the originals are "grandfathered".). Just FYI.

And I'm just curious... The "crimp" sounds like the removal of one glad hand might have been incidental and not planned. Which one do you have remaining? If it's the service line (originally on the driver's side) I'd consider moving it to the passenger side, which is a full time air supply and has good uses as a general air supply for tools and tire inflators and such.

 

[rosco]

If you use the plastic tubing, it MUST say DOT on it. While the DOT rated plastic brake line tubing is not conventional on the MV's, it has replaced copper tubing in later vehicles. It is vibration and corrision proof, and resists all fluids found around highway vehicles.

Lee in Alaska

 

[stumps]

Compression fittings are notorious for leaking. The problem is the copper tubing gets little grooves in its sidewalls from the drawing process used in its manufacture. This creates a leak between the tubing and the compression ring, prompting the installer to tighten the fitting all the more tightly. These grooves will never seal against the compression ring, regardless of how tight you make the fitting.

Fortunately, the solution is dead simple. Go to your big box store (Home Depot, Lowes, Menards...) and buy a can of Hercules Blue Block. It is an alcohol based gasket sealant... or, go to your your local automotive store, and buy a can of Permatex Super 300. Take the brush, and make a light ring of sealant around the joint between the compression ring, and the cut end of the copper tubing, and then reassemble.

No more leaks!

-Chuck

 

[Jake0147]

... it MUST say DOT on it... .

Air is secondary to deuce brakes, not primary to it. There is a failsafe and the brakes function without air. This does not require DOT approved unless you're pulling a full air brake air brake trailer. Just like horns, air seats, PTO switches and such, where after the protection valve, anything goes. Most common is to see DOT rated stuff, since it comes cheap and typically in bulk, but once you're out of the primary brakes it's fine.

 

[dusterjh]

The gladhand that is still there is on the drivers side. I took it apart again today and tried to see if there is enough room to cut off the end and try again but there isn't. I tried re-assembling and cross threaded the darn thing. So I'll be off to the parts store and see what i can find.
Jake0147, I'll check into the line that was crimped off, if I remeber right from the other day it is disconnected somewheres and it looks like they just never removed the line. So I guess I should look into finding where that line was connected and re-plumb for the passenger side.
I did see online there is a copper tube and then there is a "soft" copper tube. Which one do I need.

Thanks again folks, I really appreciate the help, hopefully someday I can do the same.

Joe
Towanda, PA

 

[Divemaster920]

Type L copper tubing not copper pipe. It will come in a roll. I hate compression fittings(I have been Plumbing Supplies for 20yrs+). I know it is more work but I would Flare the fittings.