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If the bolts don’t climb after the engine starts it is likely not charging! Most likely the alt.the relay on the fire wall can also be faulty. 

If we’re talking the same issue here ? On older trucks We used to move inlet temp to the outlet pipe of the after cooler wonder if that is an option!

Do you have a Mack trans? If so there is a torque limit switch on the rear of the trans try unplugging that!

If it were a short it will likely show up as a fault does the check engine light eliminate when the miss occurs? EUP malfunctions should show!

13 hours ago, Mack Technician said:

I’d grab a “know good” charge air temp sender from another truck and swap them out. Then take it in if no fix. 

Mack had issues with smoke stumble at low RPM. Yours should already have the fix. It was a software file or adding a 1,000 ohm resistor to the charge air temp sensor. 

Yup if it is the smoke and stumble file issue I wonder why it has chosen now to show up ?kind of odd! Something else l have been thinking is maybe a broken eup spring .just odd it’s happening in the same rpm range! The smoke and stumble usually showed up at a stop light some sort of heat sink issue either inlet sensor it though! Try to pay attention to when it happens and set instances!

Run a decent size wire from the truck frame to the box frame for ground or wait till you lift the box  a bit to establish a descent ground 

Check all of the connections on the fire wall also have seen the ground fault breaker cause issues like this try by passing it if you’re lost of prime theory don’t work.

Agree with that statement totally! Could easily start floating valves at that!

On 9/13/2019 at 4:18 PM, 1965 said:

Never seen a Mack that needed or wanted that many rpm’s. That sounds like driving a 2 stroke Detroit.

Just a note !

there was an exception ! the 325 V8 was governed at 2600 ! No load in that way they were able to use a six speed trans!

13 hours ago, Mack Technician said:

Curve settles any arguements. EZ is driving Inside the curve’s benefits.

This being said the tack seems a little high 200 or so in my mind so if he’s driving by it his sweet spot is not where we might think! 

Just my thought on it so add 200 to the s/s 1400 you get 1600/1850 roughly!! If the tack is off!

In my opinion You need to remove the valve covers an look for a valve train issue a bent push tube or the like

Sounds like the accessory relay to me!when you turn the key on is the heater fan able to run? If not replace the relay!

Between 1400 and 1650 is likely where you need to be.

That be it!  The big round thing screws in it has orings on it! the drain valve inside it has a spring behind a needle valve same as the E6

The only thing You may be able to uses is this 43MR213P2 If its still available and you will have to bush it up to 3/8 pipe!

https://www.paiindustries.com/catalog/fraCatalog.php

Did the pump pop up when u unbolted it ? This will cause em to fly apart! Also I hope you are replacing the eup bolts they tend to break when reused !

So go find two or three good quality 1/8 thick  fediloy grade eight flat washers from a bolt supply place and stack them in there the results will bed the same!you can’t not have no washer s in this location or you’ll endup in the same spot again !Fastenall to name just one.

These brackets were once fabricated and held down by two bolts and spacers it is now casted!And now one bolt and a spacer over time they have cheapened things !

Good explanation buddy! My bet is the bolts are loose inside the cover . Your on the money for the repair as well !it also held to have the torque rod on the front diff as well spread the load around!

25 minutes ago, kkheitman said:

What makes you think it would be cracked? 

I Highly doubt all the oil slobber is from just the loose studs Could be wrong However Seen it before!

Does the front diff have a bracket as well?

How are your trunnion bushings, U bolts are tight?

In my opinion judging by that pic, if you were to lift that diff out the banjo housing will be cracked LH side!

AMEN To That!

31 minutes ago, R.E.D said:

Found the issue ..3 ecm pins have completely eroded off ..need a new ecm

Beleive there is an anti wicking harness for this issue you should invest in it!

Yes it’s possible ! Check your air filter as. Well

Yup to bad the sweads didn't stick with just saws and sewing machines something they are good at!  But NO  they had to get involved in trucks and equipment too!🙄