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m2 Sportchassis cab bag leaks


hemsteadc
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Found a couple pinhole leaks in one of my cab bags.  Does anyone have any quick/temporary fixes, like tape or glue or bicycle tube repair?  Not sure this is a DIY job, and having difficulty with shops in this area.

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No good suggestions on a quick fix, but I do have a bit of experience changing the cab air bags on a Kenworth T2000.  The job itself is pretty easy.  The hardest part is access (which isn't bad on my T2000).  I can see access on an MDT being a bit more challenging, but I don't know for sure.  I use a small bottle jack (sitting on the frame and a 2x4 to spread the load on the bottom side of the cab) to lift the cab up to make access to the top and bottom of the airbags much easier.  Typically it is one or two bolts and/or clips and an air line to remove and then reconnect the new bags.

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Posted (edited)
On 5/11/2021 at 5:55 PM, Chad Heiser said:

 I do have a bit of experience changing the cab air bags on a Kenworth T2000.  The job itself is pretty easy. 

Sportchassis tells me they can do it in a half-hour.  Of course, everyone around here says 2-3 hours.  Sigh. Just not sure it's a job I want to tackle.  Thanks.

Of course I don't expect these leaks to stay small and will likely blow on me at the worst possible time.

Found a mobile mech who says he'll show up tomorrow.  I'll be amazed if he does.  With the bags. Good help is hard to find around here.    Yeah, it'll cost me, but I have more money than desire or mechanical ability.

Edit: Nobody here yet. No calls, nothing.  Why am I being lied to all the time?

Edited by hemsteadc
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  • 2 weeks later...

Have you found a fix? Do you have the replacement parts or is that part of the problem.

4 years ago, Sportchassis replaced mine after Freightliner couldn't find the leak. Of course that Freightliner service shop had some other problems.  

Clay    2015 Sportschassis M2 106 only drove less than 2300 miles last year.

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Posted (edited)
On 5/23/2021 at 8:33 AM, ms60ocb said:

Have you found a fix? Do you have the replacement parts or is that part of the problem.

The fix will be taking it to the least incompetent truck shop. Mobile service said they'd show up, twice, never did.  Other shop was so disorganized I left. The last time I used a Freightliner shop they kept it for 3 weeks.  Parts are not an issue.

I found 2 pinhole leaks in one of the cab bags.  I'm actually considering covering the holes with Gorilla glue and hoping it holds long enough to see if they are the reason the rear axle bags are also deflating without actually having leaks of their own. Sportchassis said leaking cab bags can do that, but they also didn't know what LOF meant.

Edited by hemsteadc
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The only way that leaking cab bags can drain the suspension bags, is if the suspension levelling valve is passing backwards. If it's weeping pressure back into an empty air system, you'll end up with empty suspension bags. In warmer temps, our KW will sit for a week before squatting. Cooler, it'll drop faster. Our levelling valve is of unknown age, and I don't worry enough to change it.

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On 5/11/2021 at 10:56 AM, hemsteadc said:

 Not sure this is a DIY job, and having difficulty with shops in this area.

Where you located. This appears to be a job that is not impossible for the shade tree mechanic but extremely hard without a pit because my arms are not long enough laying under neath. The truck bed makes it more difficult but not impossible.

Clay

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Do try to get it repaired as a long time diesel tech I can tell you that excessive air leaks in the chassis cause the air compressor to run or cycle more that is should and it will eventually take its toll on it, if you have access there usually easy to change. Disconnects the control and use it to overfill the bags a little the shove a precut block of wood in there for support and then swap them out refill and remove blocks. Reconnect control valve arm and your good to go

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On 5/31/2021 at 5:30 PM, TD1 said:

 Disconnects the control and use it to overfill the bags a little ..

I'm not sure what that means.  What control?

I'm getting more ready to try this myself, only first I have to have access under the truck without constant fear of it falling on me.  So I'm pouring concrete pads for ramps to elevate the truck enough to see if I can do this.  And of course that takes forever. 

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2 hours ago, hemsteadc said:

What control?

Ride height control.

 

2 hours ago, hemsteadc said:

only first I have to have access under the truck without constant fear of it falling on me

It can only go so far, like 4 inches. It won't "Lay frame", or crush you underneath, unless your a little "stouter" than most.

ETA: Instead of waiting for concrete, place wood blocking between the frame and axle, after you lift a little higher than usual, using the ride height trick posted above.

Edited by Darryl&Rita
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Posted (edited)

Got the last of the concrete poured today, so soon I'll get 'er up and get  under there and see what's what.  My favorite mechanic will absolutely not do air bags at my house.

I do not understand this truck.  For the last couple months the rear bags have been going down in concert with the cab  bags.  Now, last night, the cab bags deflated (2 known leaks) but the rears remained up.  Huh?

Edited by hemsteadc
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Posted (edited)
On 5/31/2021 at 5:30 PM, TD1 said:

. Disconnects the control and use it to overfill the bags a little 

Can I fool a lever or valve to think the bags are full?  In other words, stop air going to them?

Edited by hemsteadc
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2 hours ago, hemsteadc said:

Can I fool a lever or valve to think the bags are full?  In other words, stop air going to them?

Yes, disconnect the control rod and pull the arm in the direction of too high. Should be down. Air will be shut off, and bags will deflate.

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  • 2 weeks later...

Got the cabs bags replaced for 'only' a couple hundred bucks.  I didn't do the rears because they hadn't been leaking.  Now, after getting the cab bags replaced, the rears are leaking again.

I don't know how bags can leak intermittently.

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6 hours ago, Darryl&Rita said:

Push to connect fittings are known for this, levelling valves can also do it. Less likely is the threaded portion of the fittings.

thanks.  Oh how nice.. all the bags are staying up and she's only leaked about 10 pounds in two hours.  Yay!

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Posted (edited)

Oh Joy! 

Both cab and rear bags stayed inflated all night, and the system lost only 50lb.  I don't know what you guys experience, but losing 'only' 50lb overnight' is a major improvement for this truck.  

Edited by hemsteadc
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