Challenger

Ive had a few red engine Macks kick the ABS, ATC and malfunction light on after raining.  Its always cleared and only came back after a good rain.  Ive feel like Ive been looking for this problem for years.  Our new Granite (1500miles) did it, but this time stayed active.  I found water in the chassis connector.  There are 2 connectors just above the air dryer, left frame rail, just behind cab.  The green one has the abs/atc wires in it.  Cleaned out and applied dielectric grease to the connector.  Cleared codes and its never came back.  Did this to all the red engine Macks and I have no more abs/atc and malfunction lights on after rain.   Also did the same to the black connector

Figured I cant be the only one with this problem. 

From my experience with bad vebs it sounds something like-  

blum, blum, blum, blum, blum, blaahhh. 

Smooth running and kinda like the key shut it down.   Not cracking and popping like old Mack’s.   I installed an engine brake on a Waste Management MP7  years ago. Started it, after a few seconds it shutdown.  Thought it was more of an electrical problem.  Eventually figured out the brand new veb was bad.  I’ve seen a lot of bad vebs since then.  

May not be your problem.  But definitely worth remembering. 

Good luck 

I’m still leaning towards veb.  The engine runs normal up until brake kicks on and shutdowns.  

I would start truck, watch oil pressure gauge.  If engine shuts down when oil pressure goes up,  I would replace the VEB.  Especially since you did touched the veb doing cups.  

Just my thoughts.  

Was the tstat marked, top or front?  Was it installed correctly. 

Anybody know what would happen if you didn’t put the tstat in with marking in the right spot?  

Maybe a bad VEB

45 seconds sounds about right for oil pressure to build up.  If the veb is bad and activating the engine brake it would shut down/stall.  

Whats your description of shutting off.

examples

Shut  off like the key was off.  All power off

or

Shutting down but accessories still on.

Are you 100% sure you replaced the oil pressure sensor not the crankcase pressure sensor.  

I’ve seen people replace the crankcase pressure sensor  instead of oil pressure.  Sensors are stacked, can’t remember if the top or bottom sensor is oil pressure.

Maybe a air conditioning high pressure switch failing?    Maybe try a known good switch.  Should be the green switch/sensor on ac lines.   

Small window under starter.  2 bolts hold the cover on.  Remove cover,  turn engine until you see a flexplate bolt, remove bolt, turn engine until next bolt.  Continue 

Installing bolts is the important part.

If you drop a bolt inside while installing trans,  you’ll have to pull trans back out.  Take your time while installing the bolts.  You will have to put them all in most of the way, then go back around for final torque.  

Not difficult.  Good luck

Check your EPDM for corrosion.  The epdm is the fuse box behind the clutch pedal or where the clutch pedal would be.  The windshields would leak and water runs all over the epdm causing corrosion.  Pull a few relays out and check them. 

Mack added a little rain coat to the epdm to keep water away.  But I still see the with corrosion 

Had a truck where one headlight would turn on when the truck was sitting in the rain over night.  

Pretty sure they are behind the brake pedal and throttle pedal dash panel.  Those sensors and wires are kind of “stuffed” behind that pedal.  Like a rats nest

No fuel, no boost

Fuel and boost pressures are the main things I check with low power complaints.

You need to check your fuel pressure

I put a fitting in the fuel galley plug and use 1/4” airline and the air pressure gauge (same as the one in the cab).   I use green needle for fuel and orange for boost.  It’s not fancy or “techy” but it gets the job done.  I like to keep it simple.  

The fuel galley plug that I use is in the front of the engine, left side, directly in front of the EUPs. Under the AC compressor if you have one.  It’s a 1/4” square plug.  I use a 1/4 extension and ratchet to remove the plug.  

Maybe the tractor protection valve?

If a new part has to be repaired,  the customer should pay for a used part, not full price. But we all know that isn’t going to happen.   I’ve always sent them back.  

But then again,  the customer is probably losing more money with the added down time on waiting for a new part to show up.

Good to know Macktech689.  Thanks 

If the front rear carrier had a spacer behind/before the yoke,  it would need switch to the new rear.  I’ve seen people leave them off, with the complaints of, vibration, oil leak or noise.  

Ratios are are stamped on the front right flat spot on the carrier.  To the right of input, facing forward 

Probably because they were 1 cent cheaper.  UPS is loyal to money,  not truck makers.  

Did you try unplugging and plugging the connector back in.  It’s possible while reinstalling the connector the piece inside the cab slide  inside.  

Unplug the connector and plug it back in.  Be careful not to overtorque or cross thread the bolt that holds the connector together 

I would take it to Mack and have all softwares updated.  Maybe a communication problem between ECUs.  Maybe mid 140 (dash cluster) isn’t getting needed info from other ECUs.  

That would explain why you have the same problem with another cluster,  possible comm problem would still be there. 

Sounds like the shop doing the work doesn’t have a lot of gear experience.  You’re better off with the reman instead of some fresh out of tech school apprentice learning on your trans.  

Mack syncrhos starting failing in 2003.  This is when I started doing inframe repairs. First they said it was range shifting in reverse that was breaking snaprings.  So they updated the aux mainshaft with thicker snap rings and grooves.  Synchros kept failing.  Then it was the synchro shift fork bolt loosen up and causing incomplete shifts and eventually failure.  So start checking torque on the bolt but  Synchros kept failing.  So they updated synchro, lo and hi gears.  Guess what , you still see failures.  Then you have the barrel trans cooler under the “cactus”  hose failing and pumping coolant into the trans destroying Synchros. 

Seems like the T2 trans where doing well, then they got cheap with the T3s, it’s never been the same. 

Have synchro failures actually ever been eliminated?   I would say no. 

Updated this, updated that, is something that dealers say to make you fell better.

Have you replaced the trans fluid and filters?  Seems like people overlook trans fluid and filters.  

Fun fact- The original trans filters say “factory installed”.   

low side-1 head

High-both heads  

Truck off, run power to the terminal sticking out of valve cover.  They should make a "click" noise when the power makes contact.

Click-good solenoid.   No click-broken wire to solenoid or bad solenoid. 

You could also let truck idle and hold power to the same terminals (1at a time) and the engine brake should turn on (you'll hear brake)

If you heard both solenoids click,  but still have only 1 head working when you ran power while running,   it could be-

Loss of oil pressure in engine brake housing examples- split orings on solenoid most likely the bottom oring,  missing plugs at the end of rocker shaft (plugs look like little freeze plugs),  valve/ engine brake adjustment (in my experience this is more of a red engine problem MP8),  Jake Brake needing updated

7 inch/lbs

SPN 3249   DPF intake temp sensor.  Sensor is probably bad, replace it.  

Is it actually overheating or is the shutdown light coming on?

Maybe a bad temp sensor telling the EECU its overheating when its not?