Air Leak Behind Dash Gauge

[Wayne M]

When we parked the other day my wife said she heard air escaping. I'm hard of hear (sometimes selective) and I could not hear it. I asked her to pin point it, but that seems to be out of her mechanical realm. I had a friend over, and he pin pointed it to the red line coming off the dash gauge. I'm still under basic warranty and scheduled for the 30th of the month at the Houston Freightliner Center.

Stay tuned.

[FleetMan]

Wayne,
An old "shade tree" trick you might use is to get a length of garden hose, put one end up to your good ear and use it as a stethescope to locate an air leak.

[DaveyD1]

We also had a"air leak" at this dash unit when we got or coach and like you cuold not hear it but drove the wife crazy.While we had it at Freightliner for repairs to the brakes they fixed the problem(we did not mention this problem but they did)It turns out the air noise was from the air horn switch .Now the wife is very happy Good luck

[kenyonman]

Wayne, If your hearing is "Selective" you should have heard the leak before the wife??? Sorry no help on your problem, just helpin' a fellow Marine out. Semper Fi brother.

[Wayne M]

Fleetman,
I'd have to feel the air. Now if I had the hearing aids in it would be difficult to determine where the hiss was coming from - air gauge or.......never mind, might get me in trouble if she ever gets on the forum. (hee! hee!)

[KennethM]

Wayne, the air leak you hear is probably one of the air gauges leaking. I have had to replace both gauges under warranty #1 gauge the day we picked up the coach and #2 the next summer. They are very easy to change your self just remove the back of the dash and a thumb screw clamp holds the gauge, with zero air in the system push in on the brass collar on the air line and unplug the len-line.

[J Walker]

On Freightliner chassis the dash air gauges are digital so no air there. The air horn switch, I believe, is electric and goes to a relay that switchs on the air horn. It should be fairly easy to separate the electric wires from the air lines since the latter are much larger diameter. If all are bundled together it gets harder. Localize it and things should become much clearer. Do you lose air pressure while parked?

[Pig Trip]

I had the same symptoms. Turned out to be a bad dash air gauge. Replaced under warranty.

[chasfm11]

I'm with J Walker. The air lines for my gauges are routed to the VDC which is mounted in the passenger side rear compartment. All gauge data is driven through a common buss (Controller Area Network or CAN) on my Freightliner chassis. It is always possible that they have changed that on more recent models.

There are several possibilities for air lines under the dash:
- to the back of the parking brake switch
- the air horn relay (mine is in the genset compartment because that is where I mounted it)
- a tap for an air seat (whether one is installed or not)

Charlie

[Pigman]

Me too with a bad dash gauge. Ours had an obvious crack that was easy to see once I started looking for it.

John

[Wayne M]

Sorry I never did a follow up to this.

I had Freightliner look at it and it was decided that the dash air gauge was defective. It was replaced under warranty and all is fine - so far.