Freightliner M2 106 Air Leak... - Diesel Truck Forum - TheDieselGarage.com
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post #1 of 35 (permalink) Old 12-24-2008, 12:30 AM Thread Starter
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Freightliner M2 106 Air Leak...

A few days ago I replied to a thread on this subject where a member reported an air leak similar to mine. I finally found a manual valve with the correct thread to replace the one shown here...



...and that fixed my leak. Truck's been parked for 52 hrs now and it's only lost 10 psi, and most of that loss was due to the air cooling down because I took my first reading right after turning it off hot!

2005 Freightliner ext cab M2 Mountain Master RV Puller, CAT C7 300 HP, 6 speed Allison TRV3000, air locker 4.33 diff, Michelin 255/80R22.5 LRG tires, pulling a 2008 40' triple axle HitchHiker.

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post #2 of 35 (permalink) Old 12-29-2008, 08:16 PM
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Anyone ever rebuilt one of these automatic drains? Does it work off a float?

'93 IH 4700, 250HP DT466, L10 Cummins intercooler, 6+1, air ride.

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post #3 of 35 (permalink) Old 12-29-2008, 10:47 PM
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I've never rebuilt one, but I've replaced lots. It works off of pressure drop.
It is supposed to drain after the reservoir it is attached to has droped 2 psi below it's maximum attained pressure.
There's more info hereif you're interested.



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Anyone ever rebuilt one of these automatic drains? Does it work off a float?
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post #4 of 35 (permalink) Old 01-02-2009, 07:34 PM Thread Starter
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I've never rebuilt one, but I've replaced lots. It works off of pressure drop.
It is supposed to drain after the reservoir it is attached to has droped 2 psi below it's maximum attained pressure.
There's more info hereif you're interested.
Thanks for that link. I was going to take mine apart to see if I could figure out how it worked but you saved me the trouble! Do you see any issues with my having replaced the leaky automatic drain with a manual one as long as I remember to drain the system every week? I have hydraulic service brakes and an air activated driveshaft parking brake. As a fulltime RVer I never encounter freezing temperatures.

2005 Freightliner ext cab M2 Mountain Master RV Puller, CAT C7 300 HP, 6 speed Allison TRV3000, air locker 4.33 diff, Michelin 255/80R22.5 LRG tires, pulling a 2008 40' triple axle HitchHiker.
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post #5 of 35 (permalink) Old 01-02-2009, 11:07 PM
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I can't see any problem if it stays warm. I'm assuming it doesn't have an air dryer? We drain ours once a month or so, but we use air dryers on everything.

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Thanks for that link. I was going to take mine apart to see if I could figure out how it worked but you saved me the trouble! Do you see any issues with my having replaced the leaky automatic drain with a manual one as long as I remember to drain the system every week? I have hydraulic service brakes and an air activated driveshaft parking brake. As a fulltime RVer I never encounter freezing temperatures.
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post #6 of 35 (permalink) Old 01-12-2009, 12:20 AM
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Anyone seeing air leaks on 05 M2 secondary? Mine leaks down to 25psi in short time but can't find source.
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post #7 of 35 (permalink) Old 01-16-2009, 09:01 PM Thread Starter
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Anyone seeing air leaks on 05 M2 secondary? Mine leaks down to 25psi in short time but can't find source.
I answered a PM to 05M2 and decided to also post some of it in case it might be helpful to others. It would be useful to compile a list of the top 10 most likely places to look for air leaks.

When I bought my 05 M2 which is a 4/04 build date last Dec it would leak all its air out in about 2 hrs time after shutting it off. I found a leak in the main line to the storage tank at a coupler fitting about half way between the compressor and the tank.

After tightening that fitting it would still leak at about 10 psi per hr. Then I fiddled with the manual valve on the auto drain assembly which is shown in my pic and was located at the front bottom of the main air tank, and by repeatedly opening it and letting it snap closed I finally got that to seat without leaking. Then the truck only leaked at about 10 psi per day, but every once in awhile it would start leaking at 10 psi per hr again and I'd have to fiddle with the manual valve on the auto drain assembly again. After I replaced the auto drain assembly with the manual valve I'm back to 10 psi per day.

I've been told that if you can park your truck in a very quite location you can crawl around under the truck and hear most air leaks but as a fulltime RVer I never found a location quiet enough so I used a spray bottle of soapy water. I've also been told that half of the new trucks delivered to a dealer leak all their air out overnight so I guess my current leak rate of 10 psi per day is about as low as I'll get.

2005 Freightliner ext cab M2 Mountain Master RV Puller, CAT C7 300 HP, 6 speed Allison TRV3000, air locker 4.33 diff, Michelin 255/80R22.5 LRG tires, pulling a 2008 40' triple axle HitchHiker.
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post #8 of 35 (permalink) Old 01-18-2009, 03:38 PM
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Quote:
Originally Posted by ernesteugene View Post
Thanks for that link. I was going to take mine apart to see if I could figure out how it worked but you saved me the trouble! Do you see any issues with my having replaced the leaky automatic drain with a manual one as long as I remember to drain the system every week? I have hydraulic service brakes and an air activated driveshaft parking brake. As a fulltime RVer I never encounter freezing temperatures.
Most trucks with air dryers don't have one of those auto drains any more anyway. Sort of a belt and suspenders thing I guess. I never see any water on mine with 3 manual drains only. And I only remember to do them monthly if even that.

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post #9 of 35 (permalink) Old 01-18-2009, 03:46 PM
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M2106 air leaks

Thanks for the info ernesteugene and Birken. I did find minor seepage at one fitting on the air brake foot valve. When new the two lines to the cab air ride were not seated and leaked big time. When you located the coupler half way from comp to tank, do you remember the color of the air line? Also, mine are inside a large wire wrap/cover which I'll have to open. I have soaped every connection and air bag under the truck with no luck. I borrowed a Holloween fog machine and plan on putting the truck in my friends plumbing truck building where it is quite and no air currents. Hopefully I'll find it then. Right now the truck cab is sitting on the stops and air press is only 25 psi at the dash gauge. I wonder if the air comp. has to work harder with a leak like this? Also, frustrating is the fact the attach points for the parking brake unit in the dash have all shattered (plastic) and I had to make some shims/brackets and use 2 min. epoxy just to firm everything up so I could use the valve. This has to be common and most certainly a safety issue. At least that's what I told Freightliner. No answer from them yet!!

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post #10 of 35 (permalink) Old 01-18-2009, 08:57 PM Thread Starter
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Quote:
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...When you located the coupler half way from comp to tank, do you remember the color of the air line? Also, mine are inside a large wire wrap/cover which I'll have to open...
On my truck the main line from the compressor to the storage tank is covered in steel braid, and it's a two piece line so the coupler joint isn't covered but it wasn't clearly visible because it's located high up near the top of the undercarriage and tucked in behind some other wire bundles so I had to feel along the line with my hand to find it and use a mirror to leak check it. As I recall I needed two 5/8" wrenches to tighten it and it was quite a chore to get the wrenches on the coupler and each of the nuts!
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...I have soaped every connection and air bag under the truck with no luck...
Also check under the hood and inside the cab, the air seats and put your ear on the dash and listen for leaks in the places you can't soap.
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...I borrowed a Holloween fog machine and plan on putting the truck in my friends plumbing truck building where it is quite and no air currents. Hopefully I'll find it then...
My truck has an external quick connect air fitting to fill the tires which is another place to check for leaks. I'm wondering if you could drain the main tank and then fill it through this external quick connect air fitting with some sort of coloring agent like they do to find oil leaks? Perhaps fill it with something that has a distinct odor!
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...Right now the truck cab is sitting on the stops and air press is only 25 psi at the dash gauge...
To me this sounds like a leak in your air bags or the leveling valve! My truck would leak down to 0 psi on the dash gauge (which is another source for a leak) but my ride height didn't decrease by even 1/16"! Then if I pushed up or pulled down on the arm from the leveling valve I could hear the hiss of air being released from the air bags but as soon as I released the force on the arm the valve shut off and the hiss stopped and the new lower ride height was maintained! On the other hand my air bag hitch is connected to the main tank via a regulator valve and it did deflate as my main air tank leaked down.
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...I wonder if the air comp. has to work harder with a leak like this?...
Yes it does! When I'm rolling down the road I notice that my air gauge cycles from 105 psi to 125 psi about once every 10 min to 15 min depending on how smooth the road is. So calling normal as about 5 cycles per hr, a leak of 20 psi per hr increases the compressor load by 1 cycle per hr or about 20% more than normal.
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...Also, frustrating is the fact the attach points for the parking brake unit in the dash have all shattered (plastic) and I had to make some shims/brackets and use 2 min. epoxy just to firm everything up so I could use the valve. This has to be common and most certainly a safety issue. At least that's what I told Freightliner. No answer from them yet!!
Below is a pic of my parking brake handle, and the push/pull rod that activates the valve appears to be attached to a metal plate behind the plastic dash? Does your parking brake handle look like this?



This is my air gauge, since the truck has been parked since Mon afternoon and it has only lost about 35 psi in 5 days I'm declaring a "victory"in my air leak battle for now!


2005 Freightliner ext cab M2 Mountain Master RV Puller, CAT C7 300 HP, 6 speed Allison TRV3000, air locker 4.33 diff, Michelin 255/80R22.5 LRG tires, pulling a 2008 40' triple axle HitchHiker.
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