Can a PPV be Deleted on a M939?

[JohnnyBM931A2]

Can those that have deleted their PPV's post up a picture or two? I am scratching my head a little on how to do this.. The PPV has 2 ports that are 90 degrees apart. I can't just do regular NPT fittings.. I don't think those will work when trying to replace a component in between 2 components that cannot be moved (especially when they are not in line with each other.) Maybe some kind of flare fitting with a separate "sleeve" that you rotate and tighten down to attach it to the existing pipe/hose? Pics or tips would be greatly appreciated

 

[Suprman]

It's there for a good reason. If air pressure is low it shuts off accessories so critical air pressure is routed to the brakes where it's needed.

 

[wheelspinner]

You cannot delete the PPV safely. It needs to be serviced / replaced. I sure hope there has not been a thread on how to eliminate this vital part to the air system.

 

[JohnnyBM931A2]

I know that I need to wait for a certain pressure, so I don't need the valve. If I ever sell the truck I will install the new one before doing so. Since this truck is my daily driver I am trying to eliminate some of the weak points that fail easily or cause problems. With the cold weather that we have here, this valve is a problem. It keeps failing, so it needs to go.

I never do anything until the air pressure reaches 90 anyways, so the valve is useless to me. The only thing that I could possibly use would be the windshield wipers.. I have already been informed that the CTIS does not function until the pressure builds past 65 psi or so, so removing the PPV will not cause that to activate any earlier.

Next on the list of things to do is install the custom electric heater that I bought (and maybe upgraded alternator if I need.) After that will be adjusting and sealing my cab fully.. Might just buy a new fiberglass 1-piece top and do it that way. After that, funds allowing, will be a rollcage. After all these things are complete it will be a much better daily driver.

 

[M35A2-AZ]

I would think if it keeps failing you are getting water in it, so I would think the air dryer is not working right.

 

[wheelspinner]

Respectfully, it's not a convenience. It protects the brakes air supply should a leak develop that the compressor cannot recover from. Every single air brake vehicle has one. If they are properly serviced or replaced if bad then they do not cause any undo trouble.

 

[sandcobra164]

I'd just install the new one and service the air dryer. One option I'm considering is plumbing the governor as part of the primary air system. When my PPV valve froze, the compressor never unloaded and pegged the gauges. The safety valve would blow off every minute or so. I'd still know if the PPV froze in the future because the wipers and horn would not work.

 

[Andyrv6av8r]

The one on there that keeps failing is more than likely all crudded up and nasty inside. I experienced the same thing on my tractor but, guess what; it was in the heat of summer. Point being, they fail when they get old and corroded up not just in colder weather. They're cheap so just get a new one and play it safe.

 

[juanprado]

The m939 use an older Bendix style ppv. Kind of surprised me as the rest of the brake components are Midland. Midland made their own version and Haldex now also makes them in plastic/nylon. As long as the pressure is the same, it does not matter who makes it or what it looks like.

My Holiday inn feeling is the bendix style does not hold up real well. I don't recall selling as many ppv in my NAPA parts days as I see folks here constantly having issue with them.

 

[Suprman]

When I install accessories like an air ride seat I use a single in-out pressure protection valve. One possibility would be to eliminate the original style ppv and in its place have air come straight thru for braking while branching off to a single ppv for accessories. Protection would be the same. The over pressure issue with a frozen ppv is the air governor is past the ppv and on the accessory feed. No air to accessories is no air to governor and the compressor will not know to unload. I have seen newer styles like the lmtv with the governor mounted to the compressor. I am not sure how it is fed though. The truck could probably use a secondary moisture catch of some sort after the air dryer before the branch off. I have seen some setups with dual air dryers in series.