Freightliner ‘pass-thru’ manifold

[SquareOne]

Thought I’d let any Freightliner guys know about this info I discovered yesterday. Apparently in many Freightliner trucks (I have a Cascadia) there is a ‘pass-thru’ air line component which houses a large amount of air lines coming from outside the truck, to inside. This is located at the firewall right above where your driver foot would be , or if you’re looking from the outside....yeaaaa all those pretty colored airlines....well that’s the component I’m talking about.

This seems to be a common point of failure and also seems like a real Pain in the a$$ to change. I believe that part is a couple hundred bucks as well. Even if only one of the fittings begin to leak, it seems a replacing the entire assembly is the only option.

Since I can’t stand pissing away time/money on changing otherwise good parts I decided what did I have to lose by trying to repair the leaking fitting. Long story short, if you carefully remove the quick connect coupler from the leaking fitting, it will reveal an o-ring you now have access to. If you carefully replace that o-ring, your leak issue will be corrected for literally pennies as well as very little time/effort when compared to replacing the entire assembly.

Maybe many of you know this info, but for those who don’t, give me a shout if you need any other info.

[Rawze]

I have done this with people many times. The Volvo trucks are the same way.

The correct size 0-rings are sometimes difficult or impossible to find, but there is a simple solution to this too.

Whatever size air-line it is ... go buy a plastic air-line fitting for that size line .. take it apart the same way and get the o-ring out of it (without damaging it) .. use that o-ring to fix the block in the fire-wall.

Another option that i see people do is to drill out the one bad fitting large enough to slide the whole air line thru .. and then use a coupling on the other side to connect the hoses together. This should be done with caution though.. some of those air-lines in that block are not simply pass-thru ... but feed multiple circuits. Not all of them can simply be drilled out.
Here is one of those times it did not work for someone: http://rawze.com/forums/showthread.php?t...1#pid31941

[snailexpress]

(09-12-2021 )SquareOne Wrote:  Thought I’d let any Freightliner guys know about this info I discovered yesterday. Apparently in many Freightliner trucks (I have a Cascadia) there is a ‘pass-thru’ air line component which houses a large amount of air lines coming from outside the truck, to inside. This is located at the firewall right above where your driver foot would be , or if you’re looking from the outside....yeaaaa all those pretty colored airlines....well that’s the component I’m talking about.

This seems to be a common point of failure and also seems like a real Pain in the a$$ to change. I believe that part is a couple hundred bucks as well. Even if only one of the fittings begin to leak, it seems a replacing the entire assembly is the only option.

Since I can’t stand pissing away time/money on changing otherwise good parts I decided what did I have to lose by trying to repair the leaking fitting. Long story short, if you carefully remove the quick connect coupler from the leaking fitting, it will reveal an o-ring you now have access to. If you carefully replace that o-ring, your leak issue will be corrected for literally pennies as well as very little time/effort when compared to replacing the entire assembly.

Maybe many of you know this info, but for those who don’t, give me a shout if you need any other info.

We do it on Volvo truck every like three months interval. When tube is out check the cut end is perpendicular and surface is smooth, no reinforcement thread .
Just FYI pass thru manifold has some internal connections between ports. Not every port can be drilled thru. As an example big supply line inside the manifold connected to pressure sensor port. Same for stop light switch.

[SquareOne]

(09-12-2021 )Rawze Wrote:  ...Whatever size air-line it is ... go buy a plastic air-line fitting for that size line .. take it apart the same way and get the o-ring out of it (without damaging it) .. use that o-ring to fix the block in the fire-wall...

Thats exactly what I did. Worked well....just have to have a little patience with the O-ring. Little finesse saves a lotta dough lol

(09-12-2021 )Rawze Wrote:  Another option that i see people do is to drill out the one bad fitting large enough to slide the whole air line thru .. and then use a coupling on the other side to connect the hoses together. This should be done with caution though.. some of those air-lines in that block are not simply pass-thru ... but feed multiple circuits. Not all of them can simply be drilled out...

This was my back up plan in the event I couldn't repair the fitting. Anything beats changing out that (what looks to be ) pain in the a$$ manifold if not absolutely necessary.