Air Pissing out

[nbone28]

4 minutes ago, Joey Mack said:

What is the air pressure on the gauge when the drier blows off ? 

believe it’s 160, i’ll have to double check in the morning 

[Joey Mack]

No way.. the pop off in the tank is set to 150..  theres the issue of its 160

[Joey Mack]

If you have 160, you need to look at the pop off valve, and dial the governor down or replace it..  125-140 is good enough

[nbone28]

2 minutes ago, Joey Mack said:

If you have 160, you need to look at the pop off valve, and dial the governor down or replace it..  125-140 is good enough

Will check in the morning, 140 sounds about right. 

[Geoff Weeks]

21 minutes ago, Geoff Weeks said:

You can check another way:

DOT requirements are:

run the truck until the compressor blows off, with the brakes released (chock the wheels) shut off engine. It can leak no more than 3 psi/min per res, so for a truck with a primary and secondary air system, the truck can only loose 3 psi/min from each tank. When the trailer is connected you still can't leak more than 3 psi/min with the brakes released.

F@#$ the pressure for the moment! Will it pass the DOT test?

It is supposed to be done at pre trip, but no one ever does, including myself. I use the "duty cycle" time of the compressor while running down the road. If my compressor has high duty cycle I know I have a leak even if I can't hear it.

If you can't see 3 psi on the gauges, go 2 min and look for a 6 psi drop, or 4 min for a12 psi drop. If you can't tell 12 psi difference on a gauge reading either you need new gauges or new eyes.

[nbone28]

2 minutes ago, Geoff Weeks said:

F@#$ the pressure for the moment! Will it pass the DOT test?

It is supposed to be done at pre trip, but no one ever does, including myself. I use the "duty cycle" time of the compressor while running down the road. If my compressor has high duty cycle I know I have a leak even if I can't hear it.

If you can't see 3 psi on the gauges, go 2 min and look for a 6 psi drop, or 4 min for a12 psi drop. If you can't tell 12 psi difference on a gauge reading either you need new gauges or new eyes.

I will test it tomorrow and report back! 

[Joey Mack]

Ok.. im dropping out of this one.. sorry GW. I was just asking a simple question.  

[Geoff Weeks]

3 minutes ago, Joey Mack said:

Ok.. im dropping out of this one.. sorry GW. I was just asking a simple question.  

I wasn't criticizing your question, sorry if it came off that way I didn't mean it to. Please accept my apology. 

I was just saying, that high cut-out pressure wouldn't cause the problem he was having. 

He may have multiple problems, esp if the pressure is that high, but it wouldn't be the cause for this particular problem. 

Because of the lack of clarity from the O/P all the way through, I think focusing on one at a time. 

[70mackMB]

4 hours ago, nbone28 said:

I unhooked the emergency line from the trailer and hooked it up to my airline to air up the tires and had no problem with the button staying pushed in when hooked to that. I go back to hook it up to the trailer and it won’t stay pushed in. 

He posted this back in the middle of the 2nd page. Wouldn't this be the same as plugging off the red line using it as a tire inflater? Then it fails hooked to the trailer.    .....Hippy

[Geoff Weeks]

2 hours ago, 70mackMB said:

He posted this back in the middle of the 2nd page. Wouldn't this be the same as plugging off the red line using it as a tire inflater? Then it fails hooked to the trailer.    .....Hippy

The problem is: he doesn't know enough about air brakes to pass the pre-trip portion of the CDL test, there seams to be no way to get him to clearly answer or follow the directions.

Mecho in the 1st 2 replies was trying to get him to separate the truck from the trailer air system to see which it was in. It wasn't until much later on, that he did disconnect the trailer, by then we were well down the rabbit hole because he didn't do what was asked by the 1st guy who tried to help. I mistakenly assumed he had followed Mecho's advice and was digging deep into the truck system, when in fact he hadn't and so I sent him on a goose chase based on what he said, not what he did.

Yes, using an inflatetor hose (depending on length) is more or less plugging, but by that time the damage was done.

A person who doesn't even know the correct operating pressure of a trucks air system, should not pass a CDL test, never mind work on truck air brakes.

Ignorance is not a sin, everybody starts out not knowing stuff, however if you ask for help and are given clear instructions, either follow and report or admit you don't understand or know how to do what is asked.

The lack or clarity in his responses likely cost him the price of an MV-3 and the time it took to install.

Not knowing the working pressure of a truck air system or how to look for leaks (Something required in a pre-trip) is a clear indication that he shouldn't be working on the brake system without some qualified help right there with him.

It is no skin off my nose (or as we used to say in the repair shop "My truck works") but people can get hurt or killed if a defective vehicle is on the roads.

Again, everybody has to learn, but you have to be willing to admit your ignorance and ask questions if you don't understand what people like Mecho are asking him to do. Mecho's 1st post was to break the problem in half, the best and most basic diagnosing action. Ignoring it and not clearly saying he didn't do it, wasn't accepting help given freely. You can't learn if you are not open to it.