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Another Air Leak Thread ....


RickW

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Doing pre-trip this morning and I could hear air. It is coming from 2 different places.

 

AIR_VALVE.JPG

 

The first leak is the fitting with the red line at the top of the photo. Already tried removing the line, making clean cut and then reinserting. Still leaking. Of all the spare air fittings in my box I don't have this one. NAPA should resolve that here after my lunch break.

 

The 2nd place I can hear air is from what appears to be an exhaust port. Slow steady leak. If I remember correctly this has been discussed before but I can't find the thread. I seem to recall in the past it was a issue with the park brake valve and required replacing/rebuilding. Am I remembering correctly or is there something else I should be looking at/for?

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Guest THE TRAILERKING

You should be replacing the valve................Then also replace any bad fittings. It appears in the photo that some of the lines are pulling a side-load on the fittings. Try resolve that when putting back together.

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Carl, Thanks. I will catch up with you at the rally about the location for the "o" rings and collets. With the 90* 3/8 fitting now replaced the air leak it much improved. Due to time (or lack of) between now and the rally it will most likely wait for full repair until I return.

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Guest THE TRAILERKING

Carl, Thanks. I will catch up with you at the rally about the location for the "o" rings and collets. With the 90* 3/8 fitting now replaced the air leak it much improved. Due to time (or lack of) between now and the rally it will most likely wait for full repair until I return.

So you'll just drive it anyway...................Knowing you have air leaks!

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So you'll just drive it anyway...................Knowing you have air leaks!

It all depends on how bad the leak is. Every truck has some air leaks. Typically even new ones. If it is bad it should be corrected. If it is not, it can wait. Personally, I'd try to fix anything that accessible before the Rally if I could get the parts....even if it is not that bad now.

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Guest THE TRAILERKING

Is that valve he is pointing to in his picture the brake treadle valve? I thought that was part of the brake system! Bummer if that fails on his way to the rally.

Yes that's my point exactly................It's a leaking brake part. Period. It's not a leaking valve for your air ride seat or air horn.

I know I will be shot down again on this one or even "Deleted".

That's where the difference seems to come to play when determining "Experienced Commercial Driver" or "HDT RV'er Driver".

**Commercial driver should never driver the truck with air leaking from brake components.......

**HDT RV'er drivers figure no problem to drive truck even with leaking brake components........

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Guest THE TRAILERKING

Is that valve he is pointing to in his picture the brake treadle valve?

BINGO.........Good call MrSeas...........It's a T290182 Treadle Valve

So it's leaking a little, let's hop in and roar on down to the rally.

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Guest THE TRAILERKING

Doing pre-trip this morning and I could hear air. It is coming from 2 different places.

 

AIR_VALVE.JPG

 

The first leak is the fitting with the red line at the top of the photo. Already tried removing the line, making clean cut and then reinserting. Still leaking. Of all the spare air fittings in my box I don't have this one. NAPA should resolve that here after my lunch break.

 

The 2nd place I can hear air is from what appears to be an exhaust port. Slow steady leak. If I remember correctly this has been discussed before but I can't find the thread. I seem to recall in the past it was a issue with the park brake valve and required replacing/rebuilding. Am I remembering correctly or is there something else I should be looking at/for?

Well the best thing I've seen so far......."Doing pre-trip this morning".....

That's awesome, now the next BEST advice for you is replace the valve.

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Yes that's my point exactly................It's a leaking brake part. Period. It's not a leaking valve for your air ride seat or air horn.

I know I will be shot down again on this one or even "Deleted".

That's where the difference seems to come to play when determining "Experienced Commercial Driver" or "HDT RV'er Driver".

**Commercial driver should never driver the truck with air leaking from brake components.......

**HDT RV'er drivers figure no problem to drive truck even with leaking brake components........

Good thing you said commercial driver "should" never drive the truck that way, because they do.
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Guest THE TRAILERKING

Good thing you said commercial driver "should" never drive the truck that way, because they do.

That's why I said............."SHOULD". There are some that slack-off like a lot of the "HDT RV'ers". However there are consequences for the Commercial drivers. There should also be for the Non-Commercial people out there too. But you knew what I meant right Big'er?

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Guest THE TRAILERKING

Anyway

RickW

despite what most of the keyboard jockeys try to tell you that "It's No Big Deal, Just An Air Leak, Get At It Later".

Don't play around with a leaky treadle valve or any leak in the brake system for that matter. When things go bad I'll bet they won't be there to hold your back when you're in the front of the court room facing a judge.

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These air connections generally fail gracefully.

 

There is a reason that a slight air leak is not an automatic downcheck on a truck. I have never driven a truck, ever, that didn't leak down over a day or two or three. Even the brand new units had air leaks.

 

Its life. Do the leakdown tests on the brakes when you do the pre-trip. If you are comfortably inside the limits go have fun.

 

Geo

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Guest THE TRAILERKING

:rolleyes: It's not just an "Air Connection Failing Gracefully" Geo.

It's a bad/leaking treadle valve. How can most come on here and give such ignorant advice?

Wait ......I know the answer.........That's because most don't know any better. They have had no professional training to know the proper "Do's and Don'ts". Too much running with the mentality that "We don't have to worry about things like that" because we don't need a CDL for an RV Toter/Not For Hire type of attitude.

Why not just do everything as if you are a CDL driver? Wait........I think I know the answer to that one too.

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https://www.youtube.com/watch?v=OmOjKdExMBw

Hopefully this will help a little. I've posted the "In cab Pretrip" which includes the air segment. This is the same Pretrip that would cause the lawyers to laugh as I recall, because of UTube. The Air part starts at 4 minutes and the brake component at 7 minutes. Al does a pretty good job. It does mention listening for audible leaks but it doesn't say what to do if you hear any. What it does say is there should not be any more than a 3 psi loss after the initial depression for the truck only ... and another 3 for tandem trailer setup.

So having a leak within those tolerances, I'm taking is OK. The compressor can handle it. In a Commercial application you make a note of it and get it fixed at your earliest opportunity, wouldn't you, I don't know. Is there a rule about this??

 

Wouldn't the truck and trailer brakes lock up if you lost air to around 20 psi anyway. They both pop out when air gets low. So you would stop with the truck losing air anyway.

 

I'm no gearhead but what about doing the in cab brake check. See if the psi builds up in the approved time, see if it leaks down more or less than the 3psi for the truck in a minute and post the findings.

 

I'd ask a Volvo Service center for a definitive answer.

 

 

I don't want to see this go south like the Pretrip topic did.

 

I'll send a message to BMT truck repair as well as Berks Intertruck in Alberni. Hopefully they will provide an answer, even better if they are the same.

 

 

TK, we don't know how much it was leaking down do we, yet??

 

R

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Guest THE TRAILERKING

 

RickW

The 2nd place I can hear air is from what appears to be an exhaust port. Slow steady leak.

 

Roger Dickinson

TK, we don't know how much it was leaking down do we, yet??

Well I give up........Bad valve is a bad valve, no matter how you look at it.

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This is the Ontario reg for pass/fail on a pre-trip inspection of a vehicle or vehicle combination with air brakes.
Pretty much crystal clear with no wiggle room. If you can't meet this spec, you are down. If you can, get off your butt and make some money.
Trucks with air systems leak air. This list tells you how much is too much from the point of view of the MTO.

Geo

Use this checklist as a guide when completing an inspection of air brake system operation.

Note: When performing this inspection as part of a practical examination, indicate to the examiner what you are testing at the beginning of each segment.

Prepare the vehicle for inspection:

  • Apply the spring brakes.
  • Put wheel chocks or blocks in place.
Test low-air warning device
  • Ensure air pressure is at least 621 kPa (90 psi). (If air pressure is too low, warning will activate as soon as ignition key is turned on.)
  • Ensure key is ''on". Engine may be running or shut off. (If ignition key is not turned on the warning will not activate.)
  • Press and release the brake pedal several times until the low-air warning device activates.
  • Watch the pressure gauges and note the pressure value when the low air warning device activates. (Warning may be only a light or a light and an audible device.)

If the device fails to activate or activates below 380 kPa (55 psi), the vehicle is defective.

Test air pressure build-up time

  • If the vehicle has a trailer attached, ensure the trailer supply valve is closed (pulled out).
  • Reduce air pressure to below 552 kPa (80 psi).
  • Maintain engine speed of 600 to 900 rpm.
  • Observe time for pressure to rise from 587 to 690 kPa (85 to 100 psi) while maintaining specified engine speed.

If the air-pressure build-up time is greater than two minutes, the vehicle is defective.

Report defective vehicle conditions

Drivers are required to report defective vehicle conditions.

It is illegal to operate or drive a defective vehicle.

Test air-compressor governor settings
  • Observe the air pressure gauges until pressure ceases climbing. (Air dryer purge also signals compressor cut-out.)
  • Reduce air pressure slowly and note the point where pressure begins to climb again. (A change in the sound of the air compressor also signals compressor cut-in.)

If cut-out pressure is greater than 932 kPa (135 psi) or is less than 690 kPa (100 psi) and/or cut-in pressure is less than 552 kPa (80 psi) the vehicle is defective.

Test air-loss rate

  • Ensure vehicle is secure and release the spring brakes.
  • Ensure air-system pressure is between cut-in and cut-out settings and shut off the engine.
  • Press and hold the brake pedal in the fully applied position.
  • Observe the air-pressure gauges for one minute and note any change. (Disregard the initial pressure drop and begin test after pressure has stabilized.)

If the pressure drop exceeds the value specified for the vehicle, the vehicle is defective.

Test tractor (towing vehicle) protection valve

  • Ensure air-pressure is within its normal operating range.
  • Ensure the trailer supply valve is closed (pulled out).
  • Remove the trailer service-line coupler from the trailer or its storage location and place it where it can be observed.
  • Press and hold the brake pedal. (Note: If concerned that the vehicle has no anti-compounding valve, ensure the vehicle is secure and release the spring brakes before applying service brakes.)
  • Note whether air exhausts from the trailer service-line coupler.

If air exhausts from the trailer service line, the vehicle is defective.

Test automatic application of the trailer spring brakes

  • Ensure trailer supply valve is open (pushed in), air pressure is in the normal operating range and trailer is fully charged.
  • Close (pull out) the trailer supply valve. (Note: The trailer supply line may also be disconnected but this practice is not recommended while the line is under pressure.)
  • Air should be heard exhausting from the trailer spring brakes. (Note: If uncertain that the trailer spring brakes have applied, gently add engine power to confirm brake application.)

If the trailer spring brakes do not apply, the vehicle is defective.

Test spring (parking/emergency) brakes

  • Apply the spring-brakes.
  • Remove wheel chocks or blocks.
  • Add engine power gently to the wheels and observe the vehicle response.

If the spring brakes fail to hold the vehicle stationary, the vehicle is defective.

Inspect air-tank drain valves

  • Ensure air system pressure is within its normal operating range.
  • Drain the supply tank until it discharges only clean air.
  • Drain the remaining air-tanks.
  • Watch the discharge from the air-tanks and ensure that the drain valves function properly.

If any drain valve fails to function properly, the vehicle is defective.

Report defective vehicle conditions.

Drivers are required to report defective vehicle conditions. It is illegal to operate or drive a defective vehicle.

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So, using that logic, if I have a slow leak in a tire, which I'm aware of and monitoring, I should unquestioningly just replace the entire wheel and tire assembly???

 

I drive commercially and the leaking air valve would go on the "Fix ASAP" list, not the "Out of Service Until Fixed" list.

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Guest THE TRAILERKING

 

So, using that logic, if I have a slow leak in a tire, which I'm aware of and monitoring, I should unquestioningly just replace the entire wheel and tire assembly???

Noooo..........You should get it fixed so it doesn't leave you on the side of the road to be fixed or "Then" be replaced entirely.

 

I drive commercially and the leaking air valve would go on the "Fix ASAP" list, not the "Out of Service Until Fixed" list.

Soooo.......You then motor down the road and your knowingly leaking valve becomes worse. If you were able to STOP safely without killing anyone, now you sit on the roadside with your "Out of Service Until Fixed" sign? A big leak or a small leak is a leak which will likely get worse rather than better. Especially any valving to do with the brakes is nothing to toy with. Most don't even know what they're looking at or what it does. Your "Fix ASAP" list "Get at it later" applies to a burnt out marker light bulb not a leaking brake valve.

I'm surprised.......And you drive commercially?

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I drive commercially and the leaking air valve would go on the "Fix ASAP" list, not the "Out of Service Until Fixed" list.

Yes, that is the correct response. It is the ASAP that needs to be paid attention to. IMO. Which is why I said if I could I'd fix it before going to the Rally. Mostly for peace of mind. It is not a safety issue if the facts presented are accurate and the brake test is successful.

 

Would *I* drive it like that? Yes, if it truly was a slow leak. Ad I'd replace the valve at my earliest opportunity. And I'd "make" that opportunity.

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