Air leak help

[scubadave]

1999 Volvo VNL 610 with Cummins N14. Air gauge in dash marked F goes down faster than the other one marked R. Reading goes down to about 105 and stays there then the other guage starts going down, when it reaches 105 compressor kicks in and builds up both to 120. Cycle takes about 5 minutes from compressor start to compressor start. No love from a dealer recommend as one good at dealing with air leaks by a professional driver.  Planning on ordering a Wisper to assist me with tracking down any air leaks I can. Since the connections are most likely original I believe I may be better off replaceing the PTC connections. What size connections do I need? Are there Amazon or NAPA part numbers?

Thanks

Dave

[Alie&Jim's Carrilite]

Mix a spray bottle of soap and water then spray down all the connections on the outside of the firewall.  Look for small bubbles that look like fish eggs.  

When was the last time the front brake chambers were replaced?

 

[beemergary]

Kids bubbles works great for finding leaks. Pump your brakes and see which needle goes down. That will be one side of system but are really one. 5 minutes is a long time to go from 105-120#. My old 1984 Pete will go from 0-120# in way less time. The old girl will hold air for a week. The suspension for couple months. It even has air wipers. I think I may still have a leak inside transmission. They used the flare style fitting back then with rubber hose. 35 yrs. old and have only replaced a few of the small gauge and wiper lines.

 

[DesertMiner]

Some cool info......

 

[rickeieio]

The push to connect, aka DOT fittings, are stupid easy to refurbish,  Usually easier than replacing.  See the above link to find the orings.

Likely places for leaks are: pass through, near steering column, around the brake valve on the firewall, and one of your air tanks, a real booger to detect.

I have a whisper, and still use the bubble solution on occasion.

Edited November 9, 2018 by rickeieio

[Scrap]

Dropping pressure and then holding on the F tank sounds like the pressure protected check valve doing its job.  With it going down first without the R leaking down then it's prolly something forward of the F tank.  A supply tank leak, an air dryer problem (bad regen valve?), or governor problem?

How to check the PCCV:

https://www.tectran.com/images/pdf/TB_AD21.pdf

What to check on the dryer:

https://wheelco.com/assets/uploads/Meritor-WABCO-SS1200-SS1800-Air-Dryers-TP97101.pdf

This just start happening or has it been at it for awhile?

[scubadave]

Thanks so much for all your help.

Scrap;

First noticed last spring and as I said above I took it to a dealer and they were unable to resolve this, they did replace a couple of parts. After having the truck with them for about 2 weeks I had to leave without the issue resolved, since they had no idea.

[DesertMiner]

Lots of “accessories” run off of the front tanks!  Seats, all of your airbags, sometimes air operated shifting, also check parking brake valve assy, engine fan, most of your solenoid operated items. 

 

[scubadave]

Tracked down to it being the PTC fitting on the back of the gauge. Mine are not repairable so ordered new ones, both were leaking. Then tracked further and ended up repairing all 12 PTC fittings where they go through the firewall and one on the engine side of the firewall. Still some air in tanks after 72 hours, so is now a lot better.

[rickeieio]

Since we're talking "air", today I serviced my air drier.  Meritor 1200 w/ spin-on canister.  Thank heavens Mrs. EIEIO was there to help.  She pre-assembled the parts stack in the "spitter", and helped push the whole thing up in the base so I could install the snap ring.  It would be a piece of cake on the bench, but upside down gets tiring.

[HERO Maker]

Rick, your Lady Mechanic is a keeper!

 

[rickeieio]

5 hours ago, HERO Maker said:

Rick, your Lady Mechanic is a keeper!

 

Yup, she has other endearing qualities as well.  For instance, she buys me motorcycles.......😉

[runaway parents]

Forget the whisper .Garden hose works great cut a four foot section of hose put one end near suspected air leak put other end near your ear you will hear the air leak easily.

[adept99]

Tried the garden hose trick a couple of time. Wife looks in my ear, hose down, and claims all she can see is the gravel on the ground, and then falls over laughing. What am I doing wrong?

[Parrformance]

put a cotton ball in the ear opposite of the hose👍

[Flying Finn]

I finally found one of my more significant air leaks last week.  It was the "pan cake" in the rear brake chamber.  Had half replaced and the truck holds air for a couple days.  I give up on trying to find the others.  Crawled all over the truck with the spray bottle.  Borrowed a whisper from a friend.  Can't find  them. 

[noteven]

Folks reading this please be careful not to open the spring side of an air brake chamber. 

[noteven]

On 6/10/2019 at 12:00 PM, rickeieio said:

Yup, she has other endearing qualities as well.  For instance, she buys me motorcycles.......😉

any sisters what are single? 🤓

[Darryl&Rita]

23 minutes ago, Flying Finn said:

I finally found one of my more significant air leaks last week.  It was the "pan cake" in the rear brake chamber.  Had half replaced and the truck holds air for a couple days.  I give up on trying to find the others.  Crawled all over the truck with the spray bottle.  Borrowed a whisper from a friend.  Can't find  them. 

Why would there be an air leak, while parked, in a brake chamber? They're air to release, and shouldn't be pressurized while parked. Or, did you mean a leak underway? Either way, I'd just swap out an air pot, rather than messing with one. 

[Flying Finn]

Darryl,

When the brake release (yellow knob) is pushed in to travel, air was rushing in past the valve.  If the brake chamber is leaking air  it    is somehow circulated  back toward  the yellow knob. I had a mechanic replace what you call the air pot.  Cost for the work including labor was $160.00.

Noteven is right on. Don't do this repair yourself unless you know what you are doing.  I did not, so hired a pro.

[rickeieio]

1 hour ago, noteven said:

any sisters what are single? 🤓

One, but she's in a nursing home and lonely for a man.  Are you volunteering to cheer her up?

[Darryl&Rita]

19 minutes ago, Flying Finn said:

Darryl,

When the brake release (yellow knob) is pushed in to travel, air was rushing in past the valve.  If the brake chamber is leaking air  it    is somehow circulated  back toward  the yellow knob. I had a mechanic replace what you call the air pot.  Cost for the work including labor was $160.00.

Noteven is right on. Don't do this repair yourself unless you know what you are doing.  I did not, so hired a pro.

Makes sense now. The rushing air was trying to pressurize the air chamber, but couldn't because of the hole. The yellow knob has a proving air loop, so in the  case of a large air leak, it pops out and activates the brakes. 

[noteven]

Parking / emergency brakes are mechanical - spring actuated - by very powerful springs inside the chambers ( aka “pots”). They love to get out if you let them. 

Foundation (aka “service”) brakes are air actuated.

 

[runaway parents]

One newer trucks you can not open spring side of air chamber even if you wanted to . BUT MAKE SURE YOU IDENTIFY THESE AIR CHAMBERS BEFORE ATEMPTING THIS.OPEN THE WRONG ONE YOU WOULD PROBABLY GET SERIOUSLY HURT. Lots of  kinetic energy stored in these things.

Edited June 14, 2019 by runaway parents

[noteven]

On 6/12/2019 at 1:09 PM, rickeieio said:

One, but she's in a nursing home and lonely for a man.  Are you volunteering to cheer her up?

... and noteven goes down swinging at another poor taste attempt at trying to be funny...

my apology is extended to you guys

😕