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Meh Commander
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Discussion Starter #1
We have a pair of freightliners at work I maintain and recently found they both apparently were plumbed wrong from the get go / new.

The first was dumping a lot of air at the ABS valves.
I couldn’t see why and ended up taking it in to a Freightliner dealer shop. The 2 front valves were found to be plumbed backward.

The second was found to have no brakes ( any of 3 axles) with primary system drained.
The lines at the foot valve were found to be plumbed up from the chassis in the wrong colors causing them to be hooked up wrong / to the wrong ports.

I did some Google searching but didn’t find much
Having to trucks turn up stupid in our small fleet makes me think this has got to be common.
Both are built in the 90’s

Thanks
 

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Good while you got it apart check the electrical wiring going to the I.D and Clearance lamps on the truck tractor.
 

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We have a pair of freightliners at work I maintain and recently found they both apparently were plumbed wrong from the get go / new.

The first was dumping a lot of air at the ABS valves.
I couldn’t see why and ended up taking it in to a Freightliner dealer shop. The 2 front valves were found to be plumbed backward.

The second was found to have no brakes ( any of 3 axles) with primary system drained.
The lines at the foot valve were found to be plumbed up from the chassis in the wrong colors causing them to be hooked up wrong / to the wrong ports.

I did some Google searching but didn’t find much
Having to trucks turn up stupid in our small fleet makes me think this has got to be common.
Both are built in the 90’s

Thanks
you could trade em in for a 379.
 

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try 'jimmyg' or 'mrjimmyg'. he is not only a Freightliner tech, but one of the best
 

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I find it hard to believe tyat two trucks that are 20 years old have been setup wrong all this time and nobody noticed. .. The air leak alone would have failed any dot inspection
Posted via Mobile Device
 

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^^^^^^ This. Too much time between the Factory build and now. I would lay money that the Valves were replaced at one point or the truck were ina wreck or converted from one configuration to another.

I do outside Parts and Service Sales for a Freightliner Dealer so I've seen most factory type screw ups. Braked plumbed wrong isn't usually one of them.
 

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Meh Commander
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Discussion Starter #7
They have had these 2 trucks since new . I have all records.
One valve was changed by me 5 years ago because we were sited for it at the scales. I changed it at that time and there was no real improvement.
This is a local only 10 wheel dump that stays on the sites most of the time.
(I’m 100 percent sure I didn’t swap the lines …. I mark and tag everything always.)
But lately the compressor is getting weak and keeping air up has become an issue that lead me into looking at it closer.


The other a 50 K mile crane
Was for whatever reason never checked correctly (including by me)
Its undisputable the thing was plumbed to the foot valve in the wrong colors.
 

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They have had these 2 trucks since new . I have all records.
One valve was changed by me 5 years ago because we were sited for it at the scales. I changed it at that time and there was no real improvement.
This is a local only 10 wheel dump that stays on the sites most of the time.
(I’m 100 percent sure I didn’t swap the lines …. I mark and tag everything always.)
But lately the compressor is getting weak and keeping air up has become an issue that lead me into looking at it closer.


The other a 50 K mile crane
Was for whatever reason never checked correctly (including by me)
Its undisputable the thing was plumbed to the foot valve in the wrong colors.
If your compressor is that weak your gonna have alot of oil in the air tanks and not much for brakes,eventually it will fill the tanks so you have hydraulic brakes,not good,we had a mack years ago we'd get a gallon out of the tanks a week.
 

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Meh Commander
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Discussion Starter #9
Yes I know … it gets a new compressor as soon as they let me have it back at the shop.
But the point was
Every time brakes were applied it would dump / exhaust 20 lbs out the ext. ports of the ABS valves before they closed …. They were plumbed backward.
Now
Plumbed correctly they don’t dump air at all….you get 5 or 6 (quick) stops without building air.
 

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Just because you took it to a dealer doesnt mean the guy who did the work knew what he was doing.
Those guys work on commission so they are not heavy into troubleshooting something like that on a 20 year old truck.
They could spend hours looking for the problem and it turn out to be a bad quick release valve that pays 1/2 hour to replace.
Sounds like there are a few pieces missing to your puzzle.
 
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