wiserfrombud

Good day. I have a 2016 CXU. As I'm sure many are familiar with I have 4 air solenoids on my frame back by the 5th wheel. That row of 4 switches on the dash is all powered by 1 15amp fuse. Any time any of the solenoids go bad (I've had 4 or 5 over the years) it shows a 5th wheel slide fault message and immediately pops that 15 Amp fuse. I got the message a few weeks ago so assumed it was a bad solenoid. I disconnected the pins on the big plug on the frame until it stopped blowing the fuse. It was the solenoid that runs that air cylinder under my hood for warm intake air flapper. I replaced that solenoid and now that works and the fuse no longer blows. I'm still getting the message though and a lightning bolt on and off intermittently. I now notice my 5th wheel slide doesn't work. I tested for power at the plug in the back and there is none. So since the fuse is good, is this a bad switch at the dash or is there some kind of relay for that bank of switches or what do you figure? I'm not thinking another bad solenoid again since the fuse is no longer blowing.

Haven't been on here in a while. That boost leak ended up being the gasket between the egr valve and the manifold. I found it by spraying it down with soapy water whe idling.

Seems like good advice. I appreciate it. My go to shop has the CAC test kit which works on every truck other then Volvo/Mack thanks to their brilliant V clamp and o ring plumbing fittings. Would have been easy to find otherwise. 🙄🤷‍♂️

Just an update, there was no correlation with the boost leak and CEL. I bought an inexpensive nexus scan tool. P2200. Open circuit bank 1 NOX sensor I think is what it said. I called Mack, inlet NOX sensors on back order indefinitely with no ETA. I tried Volvo, same answer BUT they had the Dinex ones in stock. OEM was 850 bucks with a 130 dollar core. Dinex was 340 dollars so I bought the Dinex. I installed it, cleared the codes and the truck is running fantastic. As for the boost leak, I still havent tracked it down since to get to that EGR plumbing I need to pull the pipe off behind the turbo where the 7th injector is and I havent had time.

I have seen that can be an issue on these engines. I will take a closer look over there.

Good morning peeps. I have a 2016 cxu with a 505c+ and have been chasing an audible boost leak for a month or so now. My CAC cooler has been replaced with a Duralite just over a year ago. I have also gone ahead and replaced all boots/clamps on the CAC piping and the 2 o rings at the inlet/outlet of CAC. I also changed the smaller o ring at the elbow off the turbo. I went over various other clamps with an Allen key. I can still hear a leak. If I mash it to the floor I won't see more then 35lbs of boost. (Used to bury the needle at 40). Last week I had a CEL come on. I have an inexpensive scanner just to read Nd clear codes. It's a p2200 NOX bank 1 code. If cleared, it is back on within an hour. I feel these 2 issues are possibly related. Any thoughts/advice on where to look next fr the boost leak and thoughts on one of the NOX sensors actually failing or is it just a generic code due to high NOX levels from boost leak or what? Truck has 700,000 miles on it. Truck runs fantastic. Otherwise. Any help appreciated.

I find it interesting that in 4 pages of discussion, there hasn't been a single mention of fuel economy. Rolling resistance plays a HUGE role in overall fuel economy. With today's fuel prices, I don't even consider longevity. I look for lowest rolling resistance, then look for the best value based on my top picks. At 7 or 8 dollars a gallon, 1000 dollar tires quickly pay for themselves long before they are worn out. I understand this is more crucial to a guy running big miles OTR like myself versus a truck running 200 miles a day in and out of a gravel pit but in business it all adds up. I spend money on good name brand tires and I get results. My truck is at 8.54 US mpg for a 30 day average at the moment, running a 505C+. Do the math on my fuel economy versus a guy running around at 5mpg with Chinese tires and see how how much it really costs you to run those "cheap tires".

I agree. Fuel surcharges are intended for long term contracted freight. Otherwise, just quote the job with current fuel pricing in mind.

These newer emissions engines do a 1000 different things to maintain temps, dpf cleanliness, particulate, Nox, and the list goes on. Instead of worrying about how the turbo "sounds" or what it's doing at any given time, how does the truck RUN? when you mash the throttle to the floor does it make proper boost? Engine brake seem to function properly? Hopefully with today's prices you somehow monitor fuel consumption, per hour I guess for your operation. Any change? Those are all good places to start. Don't go down the path of chasing a problem that might not be there. The shops will be happy to throw parts at it for thousands per visit.

This may be dumb but have you tried messing around with the dimmer dial?

What does a fuel treatment have to do with how the rods and mains look? As far as the deep clean additive, I think most people get desperate when there is an emissions issue and start doing things like dumping additives in the fuel in hopes of fixing a legitimate emissions problem. Your money is probably better spent ensuring your top end is set properly and your 7th Injector/AHI module is functioning correctly. If all those things are working correctly, you really should only have passive regens. If it starts requesting parked regens, there is an issue that needs to be addressed. Provided you don't have 60% idle time of course. Just my opinion.

235-240 is where the engine oil should be as per the oil thermostat. 215-220 is past fan on temps. Is the fan coming on? This thing runs 220 on the water temp running down flat roads? I have a feeling the pressurizing coolant and high temps are not related though high coolant temp will magnify a pressurizing problem.

I know when I ordered my 16 CXU, I ordered it with some fancy air drier with 2 cartridges. One for water and one for oil. It's junk. There is always moisture in my air tanks. If I don't stay on top of draining those tanks, the AHI starts throwing some air purge code or something to that effect and it needs to be replaced.

I dont chime in here very often but will offer a positive oppinion on the 'new Mack truck's' as oppossd to the typical 'anything new is junk' view. In July of 2014 some of you may recall I placed an order on a 2016 Mack CXU 505c+, Eaton 13 speed, Mack S38 rears. The truck now has 1.1 million km on it (just shy of 700,000 miles) This thing has been nothing short of fantastic. The truck has given me superior service and cost of ownership in comparison to my two previous PACCAR trucks that I purchased new (2005 379 pete/C15 Cat and a 2010 KW T660/ISX). I did end up doing the problematic injector swap at around the 600,000 km mark and that set is still going strong. That aside I have only had routine maintenance. I changed the boost sensor a few months ago just to keep fuel mileage optimal but aside from that I have not had a single sensor fail on the truck. I change the 7th injector annually and have had no emmisions problems either. The truck is like clock work and is just a day after day work horse. It has a lifetime average of 7.31 US MPG running 80,000 lbs up and down the I 15 corridor. I am so happy with it. I plan on keeping this truck for the forseeable future since it has just been so good but if I had to replace it tommorow, for certain it would be another MACK.

Meh. My Cummins was multiple camshafts and dropping liners, The Mack is injectors and cups. They are all shit when they are broken. As of now I would still buy another Mack. I cannot say the same for a Cummins.