Jump to content

How to track down air leaks?


Recommended Posts

So I just had my new to meet truck dropped off. It’s a 03 elite cl700. It’s been sitting for 2 hours now. The airgage has dropped. The orange needle hasn’t moved but the green needle has dropped from 130 to halfway in the red. Also my drop axle has dropped. I am assuming these 2 things are related. Where would I start looking for air leaks? Im a total noob to this so I have to start somewhere. 
 

edit* so it also appears I have leaks behind the dash. I moved the hvac vent controls and now on whatever setting it is on I can hear air. 

Thanks 

image.jpg

Edited by Dmurph2016
Link to post
Share on other sites
  • Replies 106
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

I figured that there had to be an air dryer but I’m just not seeing it. The guy I bought it from had a few other trucks that he ran, so I am not sure if the drivers were just lazy or what. I will admi

I saw a guy killed under a dump body that fell on him when I was fairly young.  Never forgot that. If you block it up, use huge, solid pieces of wood.  Don't take chances under that thing.  I don

That little red cap valve ??   That truck can ( and likely does ) have more than one. Might find one on an air tank you can see from under the truck .  And they could be on either system.  Make liked

Posted Images

There are actuators that are controlled by air that are behind the dash that move the flaps in the vent box. These are always prone to leakage. If I remember correctly the air cylinder is white. The other air leaks can be coming from anywhere.,from air fittings, lines, valves and the air springs. Best thing to do is fix the obvious leaks that you can hear and use a sprayer with soap and water and look for the less obvious leaks. This can be a time consuming problem. I would fix the audible air leaks and not worry about those very small ones. 

  • Like 1
Link to post
Share on other sites
Posted (edited)
18 minutes ago, Vmac3 said:

There are actuators that are controlled by air that are behind the dash that move the flaps in the vent box. These are always prone to leakage. If I remember correctly the air cylinder is white. The other air leaks can be coming from anywhere.,from air fittings, lines, valves and the air springs. Best thing to do is fix the obvious leaks that you can hear and use a sprayer with soap and water and look for the less obvious leaks. This can be a time consuming problem. I would fix the audible air leaks and not worry about those very small ones. 

I am going to get soap and water and start looking, but figured it can’t hurt to ask if anyone has suggestions on where to start. 
Green needle Would be primary correct? I have an obviously big leak if it dropped for 130 to the read in less than 2 hours. 
being that the truck is air ride, does that have anything to do with it?

Edited by Dmurph2016
Link to post
Share on other sites
11 minutes ago, Dmurph2016 said:

I am going to get soap and water and start looking, but figured it can’t hurt to ask if anyone has suggestions on where to start. 
Green needle Would be primary correct? I have an obviously big leak if it dropped for 130 to the read in less than 2 hours. 
being that the truck is air ride, does that have anything to do with it?

I would start with the lift axle dropping down with the loss of air pressure.    terry:MackLogo:

Link to post
Share on other sites

"V", correct me if I am wrong, but aren't the primary and secondary needles connected to 2 different tanks?

If so, that might make it easier to isolate the system with the leak.

Edited by doubleclutchinweasel

"Eagles may soar, but weasels don't get sucked into jet engines."

Link to post
Share on other sites

If it took 2 hours of sitting turned off to drop that much then it's not a huge leak and the truck is safe to run.  But if it was running and did that then you would have a problem. 

Link to post
Share on other sites

That small picture of the dash looks pretty clean, I think maybe some pictures of the whole truck might help 😏

Sounds like maybe something with that lift axle is the biggest problem, but it actually depends on what else is on that system. IDK if that's primary or secondary on your truck. You're gonna need to listen and start squirt'n soapy water . Once you find one ....you'll catch on fast how to find an air leak.

Fix'n it ???   well that's another thing

Link to post
Share on other sites
26 minutes ago, OldRedMack said:

If it took 2 hours of sitting turned off to drop that much then it's not a huge leak and the truck is safe to run.  But if it was running and did that then you would have a problem. 

With the truck running I don’t believe the pressure drops, will have to confirm later. But I parked the truck, both the needles were at 120 or so. Shut the truck off, went inside. I came back out about 2 hours later and the lift axle has dropped (it was previously in the up position) and the green middle had dropped to about halfway in the red. The red/orange needle had not moved. So I would say it’s a separate system. But, I wanted to check something so I held down the brake petal and the pressure of the red needle dropped like a sack of potato’s. I don’t have much experience with trucks, but I am willing to learn and appreciate any help, no matter how small it may seem. 

Link to post
Share on other sites
21 minutes ago, Mark T said:

That small picture of the dash looks pretty clean, I think maybe some pictures of the whole truck might help 😏

Sounds like maybe something with that lift axle is the biggest problem, but it actually depends on what else is on that system. IDK if that's primary or secondary on your truck. You're gonna need to listen and start squirt'n soapy water . Once you find one ....you'll catch on fast how to find an air leak.

Fix'n it ???   well that's another thing

When I get it cleaned up I’ll post some pictures! When I shut the truck off in the front engine area I can hear some air, but was told that since it’s air ride it’s the bags settling. Not sure if that is part of the leak. I’m going to get a spray bottle and start checking all the hoses and whatnot but figured I would ask as maybe there’s some common areas that leak and that would give me a bit of a head start!

Link to post
Share on other sites

Anywhere there's air, there could be a leak. Your truck has two air systems, primary and secondary. Depending who tapped into where over time it's hard to guess what besides brakes comes from where.  Grab the soapy water and put it in an old Fantastic sprayer (or something)  After you find an air leak (look for the bubbles and different sound when it gets wet)  you'll catch on quick.

  • Like 1
Link to post
Share on other sites

If you have an air operated engine fan, check the line to the fan clutch.. they can chaffe where it comes up through the shroud. its at 6 O'Clock. Also, the fitting on the front of the fan can leak too. also check the treadle valve on the firewall for leaks, and the tractor protection valve on the firewall, both are next to the steering shaft. jojo

Link to post
Share on other sites
11 minutes ago, Joey Mack said:

If you have an air operated engine fan, check the line to the fan clutch.. they can chaffe where it comes up through the shroud. its at 6 O'Clock. Also, the fitting on the front of the fan can leak too. also check the treadle valve on the firewall for leaks, and the tractor protection valve on the firewall, both are next to the steering shaft. jojo

I’ll have to check if I have an air operators engine fan, I have no idea to be honest. But I’ll be out there with soap tomorrow trying to see what I can find! 

14 minutes ago, Mark T said:

Anywhere there's air, there could be a leak. Your truck has two air systems, primary and secondary. Depending who tapped into where over time it's hard to guess what besides brakes comes from where.  Grab the soapy water and put it in an old Fantastic sprayer (or something)  After you find an air leak (look for the bubbles and different sound when it gets wet)  you'll catch on quick.

Oh yeah, tomorrow will be fun trying to chase down leaks. I’m guessing for the lift axle to drop that fast it would have to be a pretty big leak. 

Link to post
Share on other sites

a small leak can do this... Do you have a way to hook shop air to the truck, so you can keep the noise level to a minimum? It makes a big difference. So what year is the truck, Tractor? Dump? Roll-off?  what is it?

  • Like 1
Link to post
Share on other sites
47 minutes ago, Joey Mack said:

a small leak can do this... Do you have a way to hook shop air to the truck, so you can keep the noise level to a minimum? It makes a big difference. So what year is the truck, Tractor? Dump? Roll-off?  what is it?

Sorry forgot to mention. It’s a 03 tri axle dump. I don’t have an air compressor but I’m sure I could borrow one.

Link to post
Share on other sites

May I suggest making a fitting that screws into the air dryer input, so that you can air-up the truck the natural way. The air will be divided between the Primary and Secondary systems, so that you can test the whole system at the same time...  The fitting is the #12 JIC fitting in the dryer base. The threads in the dryer are 1/2" NPT. you can follow it back to the compressor disscharge line to I dentify the correct one. The line will be metal braded line coming off the compressor, then under the cab it will switch to rubber, and go down to the dryer.. jojo

Edited by Joey Mack
More content needed
Link to post
Share on other sites
39 minutes ago, Joey Mack said:

May I suggest making a fitting that screws into the air dryer input, so that you can air-up the truck the natural way. The air will be divided between the Primary and Secondary systems, so that you can test the whole system at the same time...  The fitting is the #12 JIC fitting in the dryer base. The threads in the dryer are 1/2" NPT. you can follow it back to the compressor disscharge line to I dentify the correct one. The line will be metal braded line coming off the compressor, then under the cab it will switch to rubber, and go down to the dryer.. jojo

If I make a fitting and hook it up to an air compressor does the pressure release or will I have to shut the air off myself? What exactly does airing up with a compressor do? 
 

I’ll have to look into it a bit more as I’m not exactly sure what fitting I’ll need or where they go. 

Link to post
Share on other sites
4 hours ago, doubleclutchinweasel said:

"V", correct me if I am wrong, but aren't the primary and secondary needles connected to 2 different tanks?

If so, that might make it easier to isolate the system with the leak.

You would be correct my friend. It is hard to trace these air leaks down especially if you have constant ringing in your ears! I agree, try and separate the two systems and look at the most obvious, but it can be a bother tracing a leak that leaks down in a couple of hours or overnight.

I have found leaks appear when the air ride on the suspension or the cab is extended but when the air ride is at ride height the leaks go away. I would check the tractor protect valve, I believe its located above the treadle valve. These sometimes leak as well. Also check the exhaust from the dash valve, I have also seen them continuously leak.

So it can be tedious, so patience and common sense must prevail. Joey made some excellent suggestions and others too. But man it can be a pain in the a## to try and find these leaks. 

V

Link to post
Share on other sites

As joey said be sure to hook some shop air up to it, hard to hear smaller air leaks with a running truck.   terry:MackLogo:

  • Like 1
Link to post
Share on other sites
50 minutes ago, terry said:

As joey said be sure to hook some shop air up to it, hard to hear smaller air leaks with a running truck.   terry:MackLogo:

That is what I am working on, have to look and see where the fitting goes and what exactly I need. Have to look into that a bit more 

Link to post
Share on other sites

As for as using soap and water in a spray bottle i years ago used propane leak detector fluid.It was sold at any propane dealer and the good thing about it was you could spray just a small amount on the suspected leak and for a hour later it would be making large bubbles.

glenn akers

Link to post
Share on other sites
3 hours ago, theakerstwo said:

As for as using soap and water in a spray bottle i years ago used propane leak detector fluid.It was sold at any propane dealer and the good thing about it was you could spray just a small amount on the suspected leak and for a hour later it would be making large bubbles.

Thats a great idea, have never thought about using that 

A fella I  know would have at a guess at least 20 years old KW C 60? Brute with a Cat C16 pulling tripple road trains off road a lot of the time and thru all the connections it will hold air for 8 hours

As he says, you really need to keep on top of it

I think thats a fair effort and he also runs at a minimum 130 psi

Way off the subbject but this video cropped up of Goldies KW brute a bit stuck in Western QLD a couple of years ago

Truck had Gold Finger painted on the bonnet (hood for you Yankies) and his truck has Hatch Transport painted on the crates

https://www.facebook.com/639446023186634/posts/838523726612195/?d=null&vh=e

 

Paul

  • Like 1
Link to post
Share on other sites
Posted (edited)

So I only had a few min today to use the soap and water before the weather turned to rain, but here’s what I got done. 
stsrted the truck and let it air up until the governor shutoff. Shut the truck off. Could hear some air leaking from the front of the truck, o opened the hood and started spraying airlines. Not exactly sure what this thing is or does but it was bubbling at the red part. Secondly I confirmed that when I flip the switch to drop the lift axle, the green needle dropped. So it seems that there’s a leak somewhere in that system and when it loses pressure, the axle drops. It’s a start. Hopefully when the rain stops o can lift the bed up and start checking under there. As well as the brake cans as I have a feeling that could also be a culprit 

C88D9C0B-F02E-4E13-855E-664E545D178E.jpeg

Edited by Dmurph2016
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    No registered users viewing this page.


×
×
  • Create New...