M35A3 AIr-O-Matic leak

[Kadefarmer]

Have been browsing a while on here for a reason my air assist seems a little weak. Finally pulled out the dish soap leak detector and found that besides the feed line that has been mentioned several times is leaking it appears that the feed lines are also bad. Now who has suggestions on what kind of new lines to use when replacing -- is it OK and is there a way to re-use existing fittings and just replace the air lines?

 

[gimpyrobb]

If I had hoses that were leaking, I'd pull them and take them to my local Parker store. Have them make up replacements.

 

[BradBMI]

on ours we made up some dielectric hydraulic lines and added jic fittings - no more issues

 

[MAdams]

Mine had several pin hole leaks in them too. I used to have a couple race cars so I had a bunch of -6 braided hose laying around. I replaced all the hose at the same time. I reused all the old fittings as they are barbed

 

[m16ty]

I just used regular old air hose line on mine and used the crimp style air hose fittings.

 

[rustystud]

I just used regular old air hose line on mine and used the crimp style air hose fittings.

The problem with that is if you ever go off road and come across some nasty little branch and it decides to reach out and "touch" your trucks lines. I can't count the times some stupid branch (usually vine maple) has broken one of my hoses, even on my bull-dozers ! I really hate vine maple ! Did I mention how I hate vine maple ?

 

[Kadefarmer]

So would you use braided line? There is advantages of having a slightly loose connection, IE a weak point that will slide off and you can simply re-connect it instead of pulling the whole fitting, threads and all out of the cylinder and or valve?

 

[Valence]

So would you use braided line?

As in the same that's already on the truck? I thought the air-o-mattics used pretty high quality lines and, personally, I see nothing wrong with using the same type. If I needed to replace mine I would visit my local "Evco, House of Hose" and have them cut the lengths I need.

...is there a way to re-use existing fittings and just replace the air lines?

My NOS air-o-matic that I put on my M35A2 used barbed fittings (sorry, I don't know the exact name of the type) that are readily reusable. One would need to be careful when cutting the hose off the barbed fitting so as to not score the brass barbs and thus creating a spot for a future leak. If this does happen, some fine (400 grit?) sand paper can help smooth over the score line in the fitting.

There is advantages of having a slightly loose connection, IE a weak point that will slide off and you can simply re-connect it instead of pulling the whole fitting, threads and all out of the cylinder and or valve?

So you mean like something catches a hose and instead of damaging the hose it simply pulls off a fitting? That sounds like it'd be problematic as best even under normal road usage. If I were worried about that I'd just carry a few extra fittings (of appropriate sizes) and a 12' length of matching new hose and just replace the damage/broken air hose.

Worst case you can turn the T-valve under the hood on the firewall to cut off air going to your air-assist and drive with the manual steering. Even if you're running an 18" steering wheel it only requires 10% more force than a 20" steering wheel. Obviously with manual steering far more force required than with air-assist...

 

[Kadefarmer]

The only problem I see would be going to Parker and having them make you some press on type fittings. Those could in theory rip a fitting out of any cylinder it was in. Also they would be very hard to fix on a trail.Otherwise I would just purchase some bulk braided line and replace all the lines and carry, like you said, at least enough to replace the longest piece, and maybe a couple of couplings. I believe I will go with braided line, I am just curious what could cause these lines to fail the way they have, I mean to have leaks the entire length of three hoses it quite a lot -- even for lines that are 23yrs old.

 

[peashooter]

Pretty sure I just used Mcmaster.com part number 5283K12 when I did mine..... I love mcmaster! They have the injector return line fittings too.
http://www.mcmaster.com/#5283K12

 

[gimpyrobb]

So would you use braided line? There is advantages of having a slightly loose connection, IE a weak point that will slide off and you can simply re-connect it instead of pulling the whole fitting, threads and all out of the cylinder and or valve?

A loose fitting might not rip something out, BUT You'll loose all your air. Since you cannot apply the brakes(effectively) with out air, you will not be able to stop. Install quality hoses and worry about "what if" later.

 

[Kadefarmer]

If you loose a line the immediate result is the same -- no air pressure. I am not going to put some garbage line on there that could come off. But in a theoretical situation, you drive over a limb or rock or whatever and it catches your air line. I would rather it pulls off than rip the fitting off. As you point out either way you are probably screwed. I just want a way to fix it on the road rather than being stuck trying to find a new cylinder out in the boonies. At my house for that matter. I mean if this thing breaks, how am i going to go buy groceries.

 

[rustystud]

If you loose a line the immediate result is the same -- no air pressure. I am not going to put some garbage line on there that could come off. But in a theoretical situation, you drive over a limb or rock or whatever and it catches your air line. I would rather it pulls off than rip the fitting off. As you point out either way you are probably screwed. I just want a way to fix it on the road rather than being stuck trying to find a new cylinder out in the boonies. At my house for that matter. I mean if this thing breaks, how am i going to go buy groceries.

If you go with quality "Parker" steel braided hose and steel fittings you won't be ripping anything out. Unless you really get hung-up on some nasty piece of vine maple ! Have I mentioned how I hate vine maple ?
Even then though if the hose is strong enough it won't break.

 

[rustystud]

, I am just curious what could cause these lines to fail the way they have, I mean to have leaks the entire length of three hoses it quite a lot -- even for lines that are 23yrs old.[/QUOTE]


Remember that rubber rots when exposed to air. There is a shelf life on all rubber products even tires and hoses. So over time the rubber breaks down and you have leaks.