The biggest one should be if its already tuned or has the emissions removed, depending on your local emissions laws this might be illegal and won't pass an annual inspection.

Converting back to emissions intact will be very costly so make your own decisions based on the laws where you reside

Next one would be inspecting the front end such as wheel bearing play or ball joints, having larger tires or wider wheels will contribute to these wearing out quickly

Do a blowby test, flip the oil cap upside down and see if it stays put. If it bounces around then you have blowby and want to do a compression test

If it is tuned then youll want to check the transmission and look if there's any signs of an aftermarket transmission, the 68rfes are can be brittle on tuned trucks if there isn't supporting mods such as an aftermarket valvebody

Check if the trucks been studded, look around the valve cover and youll notice if there's stock headbolts or aftermarket studs, the studs help reinforce the head and prevent it from lifting as it has more tensile strength. Its not absolutely necessary but it is a big bonus especially if the truck has been tuned

Overall these 4th gens are pretty stout trucks so just general front end inspections and figuring out if it has been tuned or not

 

That’s super helpful, thank you! From what I could tell on the first walk around and test drive, everything appears to be stock, however I did not do any research prior to looking since it was a last minute test drive right before heading up camping.

Based off what you’re saying and the video Got Smoke 1 posted, I have a lot more to look at when I go back. I likely won’t go back to the dealer again until their inspection and any fixes they find are done so I want to go back with as much knowledge as possible before buying.

 

Didn’t watch video. Sorry if this is redundant. In addition to what’s mentioned above I would do the following.

Look on the EVIC and check idle hours compared to drive hours(some years have been known to reset drive hours after 1000+ hours). Not a deal breaker but nice to know how much idle time. If it’s intact, I would do a snap throttle test after it’s warmed up while looking at exhaust in mirror to see if ANY smoke appears. If you see any it’s an indication that DPF is damaged. Inside of tailpipe shouldn’t be super black and sooty. On test drive I would make sure it’s making good boost under full pedal acceleration(+30) and that exhaust brake works well. If not could be indication of bad turbo or actuator. I believe 2012 only has one engine mounted fuel filter. Later model years have improved filtration with a rear mounted water separator/filter in addition to front filter. May be a worthwhile upgrade. Bring an OBDII scanner and see if there are any codes or pending codes before/after a test drive of at least 20 minutes.

 

I’ll be sure to check all that out. One question on the exhaust brake, how exactly does that function on the 2012 Cummins? I know there is the button but I don’t know much about it. I have the GDE tune on my ecodiesel which activates the engine brake with foot off the accelerator and over 2500 RPM. It is not very noticeable until towing or driving down steep grades but it is always active.

 

I’m not entirely sure on a 2012. I have a 2017 and it has a momentary button under the radio that selects “Full” and next push is “Automatic”. Full activates basically any time you release fuel pedal and automatic activates when you touch brakes or vehicle accelerates due to grade(e.g. maintains speed) Not sure if 2012 is the same or just on/off. Hopefully someone familiar will chime in. With stock tune it activates down to 1200 RPM in gears with torque converter locked.

 

Front suspension/steering play. Cab leaks. Driveline joints. Transmission CVIs. Clogged heater core. Evidence of regular maintenance and proactive driveline fluid changes.

 

well did you buy it? how did it turn out?

 

I did not end up buying it. They did about $7k worth of work on it after the finished the inspection. I went to pick it up after the work was done and it didn’t feel right when I was driving it. The steering was all over the place when on the highway and braking (they did do some suspension and steering work) and it would not transfer to 4 wheel low, it would just make a clunk sound every time I tried.

I asked them to look into these things and they said everything was fine and even if they did find something else they have too much money into the truck and weren’t willing to do anything about it. My buddy who is the finance manager at that dealer recommended I not buy it along with my brother in law who does not work on diesels but manages a local mechanic shop. Therefore the hunt continues.