Mackpro

On some trucks we saw the starter solinoid shorting internally and making the engine die in a hard pull when the engine would lean over.

Here is a bulletin on this. https://static.nhtsa.gov/odi/tsbs/2018/MC-10152929-9999.pdf

“No Info” message on the cluster on thoses years is usually the J1708 or J1939 data link wires shorting in the engine harness. Had 2 in one week doing this and it was shorting wires in the engine harness behind the oil filters . New engine harness solved both theses trucks. Also check the engine ECM connectors for rotted pins due to antifreeze in the engine harness.

The oil leaks are probably the bottom exhaust manifold studs. They are drilled into the oil return/push tube area and you have to put RVT silicone on the studs if oil is seeping around then . This is only on the bottom studs. Using to long of bolts or the incorrect studs can actually hit the push tubes and cause issues

Going through my notes, not long ago I had a 460 CHN with low power complaint. New injectors, good fuel pressure, turbo actuator adjusted to 37 psi of boost , newest software. All perfect and ran great with no trailer. We wanted to replace the fan clutch because it was stuck on but owner declined . Finally he gave us the OK and once we replaced it and fixed the low power power problem. That fan sucks 30 to 50 HP on some engines.

I gotcha. Yea the boost pressure relief valve is a place to start.

The HP and torque curves are so narrow with the AC and even worse with the AI engine. With a AC 427 engine traveling on flat ground at 65 mph your RPM’s should be 1600. Someone might have swapped out rear axles ( ratios) or transmission and gotten the torque and HP curves out of wack. This was a common issue on the AI engine in the dump trucks we saw. The AC engine was more forgiving

Here is the bulletin https://static.nhtsa.gov/odi/tsbs/2020/MC-10180406-0001.pdf

There is a service bulletin on this issue. I believe that some on the reman carrier housing had to be ground down in some areas so the bracket would fit flush up against the carrier housing. I’ll see if I can find it and attach it here .

Like FJH mentioned, you need a boost pressure gauge. Just get a small liquid filled air pressure gauge better if it’s a 0-50 psi but a 0-100 psi will work, hook it to the intake manifold, there is a 1/8” pipe plug just for this . Using 1/4” air line run it in the cab and see what boost pressure your getting under a load, 33 psi is what I always shoot for on the ASET AC engines.

The green switch on the AC line by the drier is for the engine fan clutch only. The high/low pressure switch for the AC system/compressor clutch is on the drier itself. However if you have the factory option add on APADS system disregard the switch set up

With key on , AC switch on and blower motor on at least low speed, you should have 12 volts to at least one side of the connector on high/low switch that’s screwed on the receiver drier. If the system is full of R134a then you should have 12 volts going through the high/low switch to the compressor clutch. If no voltage , pull the cover off of the AC/ heater unit . Starting sometime around 2003-2004 Mack started putting a in line fuse below the control panel. What was happening is the AC compressor clutch was shorting out and it would fry the micro switch on the control panel. With the add on in line fuse , the fuse would blow and save the control panel. Hopefully yours has the in line fuse.

Mack won’t come out and say exactly what PSI of boost will derate it but they want the wastegate adjusted to open at 32 to 33 PSI. So I would think the derate level is higher than 33 psi. There were some software updates for the 460 CCRS if you were operating in above 4,000 feet.

Hopefully the Y hoses are still available. Best I remember they were pretty expensive