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

Screen clogged in the lower radiator Y pipe where it goes into the oil cooler. This restricts coolant to EGR cooler and it cracks . Then boost pressure is blown into cooling system when under high boost loads .

If power loss has been gradual over the years. I’d look at getting the pump timing adjusted. Timing gear train wear over time will cause the pump timing to slowly retard. I’ve seen them as much as 2 degrees below spec. I alway set them 1 to 1.5 degrees over the spec on the valve cover. Being in a RD I’d only go 1 degree over spec. CH’s and Superliners with the bigger radiators can go 1.5 degrees over. Also check you muffler. Some of the older RD’s had those small canisters mufflers that broke apart inside. And like the guys said above. Check linkage for full throttle and especially the kill leverage way forward. Chased a low power issue for over a day one time and it was the kill lever not adjusted. Also if truck has an air ride cab , be sure to check the linkage with the cab aired up. Check air filter for being put in upside down( don’t think it will even run that way though)

Good deal!!!

The EGR valve is on the RH side of the engine bolted to the exhaust manifold towards the rear . The EGR valve has about a 6 “ harness coming off of it with a 2 wire connector. This connector is usually zip tied to the very center of the back of the engine. You have to remove the lower center of the dash and remove the firewall engine cover to get to it.

Sadly it was only for the first generation of ETECH’s 1998.5 through 2001.5 then the CCRS started and they dropped the 460 XT. They did have the 460 performance and 460 economy for the CCRS but both were prone to the wastegate turbo derate issues. Had a buddy with a 1999 CL713 with the 460XT , I copied that engine data file and reflashed a lot of ECM’s to the 460 XT many years ago.

In my notes from 2010, one of the best running engines we drove was a CCRS 427 HP with 460 injectors. But also Mack did a software change to a different data file that really made it come alive. Best I remember it was originally a 460 CCRS with the classic random derate due to the turbo issues. Detuned engine software to 427 and installed a 427 turbo while leaving the 460 HP injectors. Performance took a hit more than we thought it should, corporate sent us a different data file and bam we gained it all back and then some.

Some of the delete programs also do the EGR valve and some don’t. I would unplug the EGR valve and run it. The deletes on Mack’s are so hard to get right because of so many changes between every 2 years of production. 2008-2009 were DPF only. 2010-2012 DPF and DEF/SCR non-OBD. 2013-2014 was a big jump in wiring and in software to OBD. 2015-2016 was the GHG greenhouse gas emissions years with different software and injectors. Then common rail started in 2017. Biggest complaint after a delete is the fan clutch either won’t come on and the truck over heats or it’s stuck on all the time. Followed closely by the truck has no power now after the delete. Usually caused by EGR deleted and not unplugged and blocked off. Even if EGR is deleted and blocked it the valve still need to be unplugged. Also on some years the turbo actuator was on the same data link as the DEF level sensor. Wrong delete gets put in to kill the DEF level sensor and it also kills the turbo actuator.

In the last few years we have seen that the factory doesn’t grease or tighten any thing very good. As in no grease on the king pins and front steer axle U-bolts loose. Sometimes the dealership catches it , sometimes not. I vote spring eye bushings or loose U bolts

Check fuses up in top of dash, there should be a bigger square on for the blower motor then one for the control panel. Also there is also one labeled something like sleeper AC or Sleeper HVAC , check this one as well even if you don’t have a sleeper. If all that is good see if the control panel lights up if you push the fresh air / recirculate button or the AC button. The HVAC unit has its own wiring harness that plugs into the main cab harness, you can see this harness connection to the left of the HVAC unit, well below the dash fuse box. The harness is known to rub on the metal braces and brackets in the area around the harness connector.

The lower fan speeds go through the resistor. High is usually direct straight from the switch. Usually the back of the switch is melted. This is usually because the cabin air filter is clogged/dirty and the blower motor is trying to pull air through the dirty cabin air filter and it over heats the wires, switch and connector on the HVAC control panel. The cabin air filter needs to be changed at least every year. If it’s a farm truck or used in dusty environment then every 3 to 6 months. The older trucks came with a blue mesh screen filter that you could wash out. It’s now been replaced with a fabric house style filter that you just throw away. Super easy to change except on the older CXU, CHU and GU trucks. A little harder to change on the AN, PI and GR trucks due to kick panel redesign. Also alway run in recirculating mode keeps from drawing in dust and other stuff that clogs the filter .