Checking for Air Leak

[Papa Rick]

Need some advice on where to check for air leak? Have used the spray water and bottle and tried to find the leak (Cannot hear it, but see it on my gauge).

When driving it will go down from 120 to 100 and then the compressor kicks in and brings it back to 120. Idling it will do the same as running. If I leave it overnight then it goes down to 90 to 95 and stops leaking down?

The drop does not change if I am hooked to a trailer or not.

It will drop while driving from 120 to 100 in 5 to 8 minutes, and figured at this rate, I could just crank it up let it idle and find the leak fast, but not happening.

Any advice on where to check?

[NotSteve]

My guess is one of the air lines has a small hole in it from rubbing up against another hose or a part. Same thing happened to me and went on for a long time until one day I was finally able to hear a hiss and found the leak in a hose going to the front rear tandem brakes.

[Bobby]

Rick
Check the air line to the fan clutch. It's fabric covered from the factory. Spray it with some soapy water. I was loosing alot of air from this line, but couldn't hear it, as it was fine pin holes or cracks all along the hose.

[BluHeeler]

My two cents are probably unnecessary and obvious to everyone. My truck has always cycled the pressure, although I've never timed it to see if it drops as fast as yours.

[NotSteve]

Hey Blu,

You and your dog need to be in the next Die Hard movie as the bad guy.

Oh yea, and if you see my truck and it's night, what until daylight to say hello.

[pdm]

Check the air valve for the suspension & the supply line from the tank. It should go through a presure protection valve that will keep the truck air up if there is a problem in the air bags etc. If the leak is in the bags they will go down over time & probably leak faster with a load on.

[sbatson]

I have had nothing but problems with mine, the compressor blows off every 5 to 10 secounds and it just loses air bad, I can sit at a truck stop and watch the air gauge fall ( with loaded trailer it does it bad) and the compressor will not come on untill I hold the pedal down to 1400 rpm's so the air will build and just falls back down once it blows off but with out a load on it still loses air just not as fast, when I come home ( no trailer) it leaks down in a day.I'm taking it to the shop Monday and I'll let you know what comes out of it, I cant stand it anymore PSSSS PSSSS PSSSSS PSSSSS and RUMMMMMM RUMMMMM RUMMMMM when i need to get back on the road,just enough to drive you crazy!!!

[Doghouse]

Hey Blu,

You and your dog need to be in the next Die Hard movie as the bad guy.

Oh yea, and if you see my truck and it's night, what until daylight to say hello.

The price of fame brother,...the price of fame

[boneebone]

The leak could be coming from the fan clutch itself internally, I had a air leak for awhile and could never find it, until I took it to a dealer and they pinched the air line going to the fan clutch and the leak stopped.

The seals in the fan clutch can go bad creating a air leak. You need to rebuild your fan clutch in that case.

[Papa Rick]

Finally had time to try release the brakes, push the brake pedal down and watch and listen. Did this several times and it never leaked down??

I cannot hear it leaking, nor have I found the source of it yet, but hopefully I will in time.

I can't figure out why if left overnight it leaks down to 90, and left over the weekend it leaks down to 70?

[sbatson]

Well got mine fixed, they replaced the air dryer filter and found leaks around the dryer and some lines coming off the dryer and and one the pop off valve on one tank and the drain cock on the other tank, seemed to fix it so far.

[Kranky]

A truck with air ride suspension will normally use air when in operation due to the up & down travel of the air suspension and the ride height valve constantly exhausting air from the bags and then adding air to the bags to maintain the constant ride height.

If it still has 90 to 95 PSI after an overnight shutdown, I wouldn't be concerned about it.

[BluHeeler]

The new board keeps rejecting my photo, maybe you were onto something there NotSteve !!

I did have parts in two movies last winter though....look for me in, "Management" with Jennifer Aniston & Woody Harrelson & "The Burning Plain" with Charlize Theron and Kim Basinger. I get "extra" roles through an agency when they are filming in Oregon. And they don't let you anywhere close to the stars, they have big, (uglier than me) bodyguards.

Hey Blu,

You and your dog need to be in the next Die Hard movie as the bad guy.

Oh yea, and if you see my truck and it's night, what until daylight to say hello.