427 aset ac ..

[Artful dodger]

So I wana start with thanks gotten some incredible help thru this forum I need more . As a few of the fellas on here know I bought  Mack having no idea that they where so diff than the rest of the field.. thought I was getting an e7 per the seller nope 427 asset ac.. hooking it up to computer that’s available it pushing 426 hp it has all new epus new compressor new pulleys new steering box new radiator new fuel lines newer suspension on the truck still Hendrickson air ride tho . I driven owned and repaired trucks most my life so I’m not green there except  for this motor .. it was deleted exhaust to egr plugged coolant still runnin thru egr  cooler I’ve driven a lot 400 hp trucks and this one doesn’t seem to have the power those do..  is it a Mack thing ? rearends and tranny maybe  think it came with rearends and tranny from factory  ??

[Joey Mack]

yep,  its the treadle valve..  just for kicks, can you reach under the dash and pull the dust boot back on the brake pedal piston and spray some lube in there?  maybe the piston is a little sticky.  Its a tight fit to get in there..

[Artful dodger]

I’ll give it a shot would that valve piss like that if a brake can isn’t working properly or another valve in the air line spiderweb from hell 

[Artful dodger]

So if I push the brake pedal it stops just tried it truck off so i can hear  and it quits 

[Joey Mack]

yes thats possible, my thought right now is to see if the piston is stuck with slight pressure on the treadle valve allowing air to leak by... 

[Joey Mack]

ok,  well its likely the valve then,  there is a piston and o-rings inside the valve that can certainly wear a grove that will allow air to slip by..  try the spray lube thing if you can fit in there and get it.  

[Joey Mack]

if you end up replacing the valve, you may want to leave the lines in the fittings and un-screw the fittings from the valve,  ( quick release fittings) . if you even get the lines out, you will pay hell to get them in without leaks..

[Artful dodger]

Ya damn it if I just barely put pressure on the brake pedal it stops if I push hard on brake it starts again this is called treadle valve /brake valve ? or pretty universal or Mack specific? . Also joe is it best to change both u joints if have to change 1 front one at carrier bearing was bad got bad vibration the back one same axle has a little play but not much should I change it or wait till it gets worse I don’t know if the back one can ruin the new front one I guess what I’m getting at 

[Joey Mack]

of course both at one time is good,, Not saying to do crappy work here, but if the out put joint is in good condition, and not spinning the caps, and the yoke bolt is tight , and the yoke is secured,  I would leave it alone.. does it take grease good? I think the treadle is NOT Mack Specific..  there should be a tag on one of the bolts with the part number.. Bendix is common, but some have Wabco parts..

[Artful dodger]

Ya it takes grease i bought 2 u joints and can change it right now I just didn’t know if should or needed to the front one move a lot I think when carrier bearing saddle came loose and was everywhere it caused u joint to go bad but I don’t know how long these have been on truck or anything so who knows 

[Artful dodger]

Thought I’d drive it if vibration is gone the let it be ya know

[fjh]

just something i suggest trying is on level ground release the the spring brakes see if this changes the leak at the treadle im thinking check valve here just something to rule out before replacing the treadle! 

[Joey Mack]

Yep, trying to eliminate having to R+R the valve for sure..  It's a PITA..

[Artful dodger]

Ok how are you fjh by the time we are done we will have rebuilt a Mack I believe lol I’ll pull up on the rd and try that

[Artful dodger]

Ya it looks like it I haven’t run into to much of Mack stuff that’s not a pita

[fjh]

1 minute ago, Joey Mack said:

Yep, trying to eliminate having to R+R the valve for sure..  It's a PITA..

Need to take in all the evidence before you pounce! 

[Joey Mack]

yep, and the ASET-C engine you have, has a lot of SH!T bolted to it..  the good thing is....  you found the BMT Guy's...  Jojo

[fjh]

3 minutes ago, Artful dodger said:

Ya it looks like it I haven’t run into to much of Mack stuff that’s not a pita

Dodger did you get the clutch adjusted right ?

[Artful dodger]

Ya I’m grateful engine has a ton of torque like it has more torque than my 6nz did I think I don’t know why I like this thing so much but I do 

[Artful dodger]

Fjh I did sir it’s gona need a clutch brake before long I thing I just keep adjusting it every so often as needed but it’s doin fine and the truck runs good man I’m probably the first owner to change oil every 10 000 it gets Lucas with every change fuel additive the clean it and good oil out in it 

[Artful dodger]

 

 

[Artful dodger]

Vibration is gone 

[Joey Mack]

Dammit Man....  your fast at checking this stuff out..   Great Job..

[Artful dodger]

Joe there’s so much shit bolted to it I’ve sat out there in a chair taking pictures of stuff playin the the guess what I do game I try and figure out before I look it up

[Joey Mack]

well bud, gotta go out to my shop..  got a little welding to do..  My Lovely wife load tested the deck on her Zero turn mower..  broke one side right of...  have fun and good luck..  Jojo

[Artful dodger]

Joe I work unbelievably hard to try and do what u all suggest u invest ur time in me least i can do is get after it when i can Fjh does not leak when brakes are released im sitting in the rd brakes released truck off no leak