Low mileage 2011 f750 Cummins 6.7
08-06-2020, (Subject: Low mileage 2011 f750 Cummins 6.7 ) 
Post: #1
Low mileage 2011 f750 Cummins 6.7
First of all, hello everyone! New to the forum, but I've been poking around on here for the last month or so, doing some research.

Last year, I purchased a 2011 f750 with the Cummins isb 6.7 and Allison 3000, flat bed super crew truck from work. It only has 23000 miles, and i got it from work, where it rarely got used. In fact, it wasn't recent on tabs for 2 years. It has about 560 hours of idle time on it, and being a def/dpf truck, that has me thinking it needs some cleaning.

I finally got the title all squared away, so I've got a few miles on it now, and already had my first def related issue. Had the code for the pump not making pressure, so I dumped the def tank and filled with new fluid, and now it is passing the def pump leak test in insite.. I ordered a filter, and will swap once it shows up..

Anyways, cleared the codes and she is back on the road.. I plan to use the truck to haul my toy trailer to the dunes, which is a long drive, and want it to be reliable.

Hoping I can get some thoughts from you folks on what you'd recommend?!?!

I've changed the def fluid, oil, filter and both fuel filters. Drained the fuel, and got new batteries. As mentioned above. I have insite.

Thanks
Jason from MN
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08-07-2020, (Subject: Low mileage 2011 f750 Cummins 6.7 ) 
Post: #2
RE: Low mileage 2011 f750 Cummins 6.7
egr tune-up is next.


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08-07-2020, (Subject: Low mileage 2011 f750 Cummins 6.7 ) 
Post: #3
RE: Low mileage 2011 f750 Cummins 6.7
I don't really know that motor, but I am sure it has an intake manifold pressure sensor along with the exhaust back pressure sensor, I would at least inspect those, if dirty, just replace, EGR Tuneup. May want to inspect both the after treatment and SCR dosers. Odds are the SCR doser will fail long before the after treatment at the turbo will. If like our big trucks, there is a filter for the SCR system, a spin on like an oil filter, if it does have one, replace it.

SCR fluid, I know this from the pick up forums, buy the freshest stuff you can get. I know the other guys, Duramaxx, do not like old, as in sitting on the shelf for a year or more, DEF Fluid. No clue if the little Cummins is as picky.

I would run a Regen and see what the readings on the cans are too, odds are they are still good with such few miles, but sitting can do some bad things, Lot Rot, and it can be expensive.

I would also inspect the drive line and drive shaft. Inspect the u-joints, they sit they rust internally and fail. Me, I would simply replace the u-joints, just for peace of mind, been there and done that. Towing bills are not cheap.

That is off the top of my head... Sounds like you got a nice rig.


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08-07-2020, (Subject: Low mileage 2011 f750 Cummins 6.7 ) 
Post: #4
RE: Low mileage 2011 f750 Cummins 6.7
Those engines may have a fuel pump like the 2250's if it does it may need updated guts. Just a thought/ something to look into.


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08-07-2020, (Subject: Low mileage 2011 f750 Cummins 6.7 ) 
Post: #5
RE: Low mileage 2011 f750 Cummins 6.7
Thanks for the list! I know she's not a Pete or anything, but it definitely pulls for my needs.

Ill run a parked Regen today or tomorrow and get some readings. As for the scr, it has an open campaign on quickserve, so Cummins will be replacing that ! The def filter is in the pump, and I'm changing that out when it arrives.

Of course the tires are original and 9 years old now. They've got to go.

For the doser, are these serviceable? Or just swap them out?

I'll try to locate some info on the fuel pump. Didn't know anything about the internals.

Once again, thanks for the list.
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08-07-2020, (Subject: Low mileage 2011 f750 Cummins 6.7 ) 
Post: #6
RE: Low mileage 2011 f750 Cummins 6.7
The SCR doser crystalizes, I don't believe there is much that can be done to them other than replacing. If you do replace, make sure there is no core deposit on it, don't throw it out. The exhaust after treatment can sometimes be cleaned up, the spray pattern is the concern when it injects fuel into the exhaust. There is a parts core deposit on that doser, at least for the ones on our trucks. If your forced regen goes ok, and the numbers are good, the dosers are probably ok. I would think the exhaust doser is fine, it would be the SCR doser I would be concerned about due to the nature of Urea, as it is prone to crystalization.

I would EGR Tuneup, replace those sensors.

SCR Service, inspect or replace the SCR Doser.

Replace U-Joints in drive line, if there is a carrier bearing, replace it, change fluids in pigs, transmission and motor, all new filters. Keep an eye on the pinion seals, may want to replace those too when you do the u-joints if you see any oil weeping around them. Check the wheel/Axle seals too when you have those tires off.

Your issue will be the sitting, that Lot Rot. It does more damage than you can imagine, I know, my truck had it when I bought it.

I would not go anywhere in this truck pulling a trailer until all of these areas are gone over and inspected. It sounds paranoid to some guys, but unfortunately, lot rot is a very real condition that affects many systems on a vehicle.


User's Signature: 2008 ProStar, OEM 600hp CM-871, 18spd, 3:42, in framed in Rawze's driveway. Every day is a fresh new episode of, "The Twilight Zone"... Rod Serling lives rent free in my head. I can smell the Chesterfields.
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08-07-2020, (Subject: Low mileage 2011 f750 Cummins 6.7 ) 
Post: #7
RE: Low mileage 2011 f750 Cummins 6.7
Yep. Sitting is no good. But for what I got the truck for, after doing all the work, it should be a pretty good hauler.

With the urea doser, when I was looking for leaks, I noticed there is quite a bit of crystallization hanging off the doser flange. Looks like those hanging rocks you see in caves. There were no active leaks, but my guess is that gasket is gone.

I think what I'll do is let Cummins replace that scr system that's under recall. Then tear into the service you guys are recommending when I get it back.

Don't have a good spot at the house here to do a forced Regen. But have a buddy with a gravel pad nearby. I'll report back when I have the data.

Sure would be nice if we didn't have all this EPA garbage. I'm ok with the idea of cleaner emissions, but I don't want the truck to shut me down on the side of the road over some nonsense pump pressure issues that aren't really engine protection. Rather, sitting on the side of i90 is less safe.
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08-07-2020, (Subject: Low mileage 2011 f750 Cummins 6.7 ) 
Post: #8
RE: Low mileage 2011 f750 Cummins 6.7
That hanging crystalized def shows that the doser valve was leaking. Hopefully they replace it in the campaign. You will need to investigate the tank, pump and lines for buildup and blockages. If the truck will be sitting for extended periods of time you may want to look in to a way of draining and flushing the DEF system as a means to prevent buildup.

Crystalized DEF is supposed to melt around 200-220F or so, plus the solution is largely water to begin with. Boiling water might clean off any buildup, especially in tanks and lines.

One of the best ways to keep the aftertreatment system healthy is too keep the engine running clean and efficient. Don't even think about any kind of aftermarket tuning or performance BS. (Not saying that was your plan, just a warning for anyone reading.) The more boost and power you use, the greater the soot that will be produced and the harder the systems will have to work to remove it from the exhaust.

Also, at that age I would be checking for boost leaks and exhaust leaks. Both will negatively impact how the engine runs and how the aftertreatment system operates.

The 6.7 is a common rail, but not sure if it uses the same type of pump as the 2250/2350/x15 ISX engines. I have a 2006 5.9l common rail dodge and it's a different pump. The 6.7 came out in 2007, long before the troublesome pumps first appeared in the ISX in 2010.


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08-07-2020, (Subject: Low mileage 2011 f750 Cummins 6.7 ) 
Post: #9
RE: Low mileage 2011 f750 Cummins 6.7
(08-07-2020 )JimT Wrote:  The 6.7 came out in 2007, long before the troublesome pumps first appeared in the ISX in 2010.

His truck is a 2011 so I really wonder if it's got the infamous grenade style pump and possibly with the ceramic plungers?? Worth looking into for sure.


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