Looking for real world feedback on the PACAR MX 13

The MX engine is interesting in that it control's it's own power supply. By this I mean that the engine power relay (that supplies power to the engine computer) is ground controlled, and the engine computer controls the ground. This allows the engine computer to maintain power to itself for a few seconds after you shut the key off. I'd start by testing the relay, and load testing the control wires to the relay.

Alternatively, you could toss a new engine power relay in the vehicle and see if the problem goes away. That would be a lot cheaper and worth a try before paying $125/hr for diagnostics.

That heavily depends on the vehicle. Do you have fairings or not? It gets a bit complicated as even the wiring harness is designed by what side the DEF tank is on. So, you'd end up spending a good chunk of money on getting the harness extended or replaced, we'd have to find a suitable place to mount it and drill holes through the frame rail, then order a new DEF pressure line (line from pump to doser) that would be a proper fit for the new tank location.

I work for western peterbilt in Fife, WA on pacific highway.

 

I'm going to assume there is a fuel tank on the driver's side behind that fairing.

With that assumption, our only real financially feasible option (meaning, the only option that doesn't require completely relocating everything on the passenger side of the truck) would be to remove that chain hanger and step (move it to the other side) and put it there.

You could change the fuel tank on the driver's side to a smaller tank and then mount the def tank next to it.

You cannot really just swap it from one side to the other while maintaining the location due to the battery box that is incorporated into the driver's cab entry step.

 

plenty of room to put in def tank on drivers side even with the fuel tank that is there, could I just put in a tank on the drivers side and connect it to the one on the passenger side,as long as we run power to the driverside tank to run the heater for the def system?

 

I mean, is it possible? Sure, anything is possible. I would not recommend it though. Actually, I'm not sure you'd even be able to do it without having a software engineer rewrite your ECM software by hand.

That tank has a $1000+ pump module mounted to the bottom of it. Not to mention the expensive ### level sender/temperature sensor/pickup tubes.

The DEF tank is heated by coolant that runs through it. The DEF lines are electronically heated. You've got one harness that runs from the aftertreatment system to the DEF tank. You'd be looking at relocating the reverting valve (coolant control valve), relocating the tank, extending the aftertreatment harness, getting a new DEF pressure line, and cutting a hole through that fairing and putting in that plastic insert so you could get access to the filler neck.

 

As far as just running a pickup/return line from the pump where it's at now to a new tank on the other side (and leaving everything else as it is), it may work. It may not.

The issue is that the pump clears those pickup/return lines after you shut the truck off, this is to prevent the line exploding if the DEF freezes. The pump may not be able to clear a line that long (not to mention, I don't think they make a line that long). The pump may have issues priming with such a long pickup. And finally, the DEF system may throw a fault code for the electric heater on such a long line.

 

say to buy a spare tank,mount it on the driverside



this one is for sale for $500.00 either at van haggs or tpi, comes with mounting brackets,figure to put in hose's and fittings to connect tanks put a hole in ferrings?

 

in the oilfields of North Dakota we used to run 12 volt heaters on our valves,vent lines anything that would freeze.or should I just save my money, and do it right and re-order evertything from a 2013 truck that would have everything def on the driverside and change it like that?

 

See the last post I just put up.

I wouldn't try to run them together (meaning one main tank, one remote tank with the lines connected). It'd be a pain in the butt. With the way the computers control these tanks, I'm not sure its physically possible without getting a software engineer out to mess with the base code of your ECM.

Even with fuel tank equalization (a system that's been out for decades), I still get brand new trucks where the factory didn't get that right.

 

You cannot directly hook a 12v heater to those lines. If they are heated for more than 30s or so they will melt. The computer shuts the heaters on and off repeatedly to control temperature.

Honestly, from a money standpoint, I believe you'd most likely save money if you bought the factory parts and had a shop swap everything over. The amount of labor you'd spend trying to have some bonehead greasemonkey like me try to reverse engineer that system would be exponential.