6.7 vs 5.9 Reliability
 

I've watched with some amusement the banter about how crappy our 6.7 engines are. Well I agree, sort of. The EPA imposed this stuff on all the diesel truck brands. Though the DEF system may be better in some respects all the truck brands suffer from problems to some degree, and it's largely NOT their fault!

The systems complexity on all the diesel truck engines has increased as each new emissions regulation was imposed. To say the 6.7 is a "bad engine" just isn't fair. Frankly, in most respects the truck makers have made incremental improvement in their trucks over the years.

My '93 CTD was pretty bullet proof and the 160 HP didn't push the modified 727 transmission too hard. As a result, I'm nearing 170,000 miles on mine with virtually nothing done but routine maintenance while spending most of it's life pulling either a horse trailer or a large travel trailer. My '99 CTD has nearly 140,000 miles of similar duty with the much maligned 48RE transmission and again haven't done anything besides routine stuff and replaced a lift pump. My '07.5 6.7 that has remained stock for it's 43,000 miles has been....perfect except for fuel economy. My '11 CTD doesn't have enough time to say it's perfect but the mileage has returned with the deletes. Sooo.... I don't have any problem with the new stuff. There is nothing on the new trucks that can't be fixed by removing the EPA mandated stuff.

I love my 6.7 just as much as I like my 5.9's. Well, maybe I love the 6.7 just a bit more because it's a pulling beast. :cool:

I totally agree that yanking the EPA mandated tree hugger love is about the best thing you can do if you are going to keep the truck for a while and drive it a long ways. I havn't heard anyone slamming the 6.7 over much more than this - but I AM hard of hearing. (I played with too many really big guns when I was young and dumb.)

I'm wondering if it's all a conspiracy. Chrysler/Cummins might figure you'll yank the emissions stuff to make it run right, voiding your warranty and letting them off the hook. But ironically, a truck stripped of the EGR and DPF (and at stock power level) will have fewer trips to the dealer anyway. And whatever damage you do the environment you'll more than repay by getting better MPGs.

I found this elsewhere from a hotshotter running a 2010 6.7. I believe it was deleted. Posted by Littleolehotshotter:


Here is my list of things that broke on the truck so far. Keep in mind what the truck does for a living.
avg 33,000 pounds on the cat scales 99.9% of its life OTR thru 25 states during all seasons w/ a few different drivers.

Truck has 13,200 hours as of 410,000 miles avg out at 31 mph... How do you check??? Turn key to run and hold trip reset for 10 seconds!!!!

150,000 Miles
*New Ac compressor
*New All Joints in the shaft
*New Fan Clutch

210,000 Miles
*Moog Outer Tie Rods
*First Alignment

230,000 Miles
*Tranny Seals blown, lost 5-6. Added NEW REMAN TRANSMISSION w/ upgraded VB & tc cost $3000 (Reman)
*New transmission mount
*Replaced all 4 rotors (Wow, did they have lips on them, looks like only 3/4 of pads were working
*Wheel Bearing/Hub assemblys replaced. (FIRST TIME, left side you hear marbles and bounces around, right side feels like no grease.
*Exhaust Manifold Gaskets Replaced

270,000 Miles
*ADDED STAGE 2 Custom Towing Trans Tune (BGCHRYSLER *DAVE*)
*New Rack & Pinion*dang inner rods were shot* (Both Sides Clanked, passenger side chewing tires)
*Changed Coolant Very First Time (Coolant Tested OK Still)

300,000 Miles
*Replaced Rear Ujoint in driveshaft
*Replace tstat w/ stock 190f (no rust) Prolly didnt need changing
*Replaced Rear Calipers.
*Replaced Fuel pump ***Crazy DTC's & LIMP MODE*** HELP, LIMP MODE???? several DTC's <---Link
*Fuel Control Actuactor (FCA) ***Crazy Stalling Issues**** Crazy stalling issues????? <---Link
*Flashed ECU version from AU to Latest 9/19/10 (No reason)
*Fuel light gauge went out (Still Broke)

320,000 Miles
*Sheared off driver side studs, replaced both sides all studs on hub (overweight problem on rear end possibly or rusted thru studs?? or driver not doing pre-trip inspection))
*Upper/Lower Ball joints replaced first time (not bad, huh) (moog)
*Turbo Speed Sensor (DTC p2579/making the exhaust brake barely work
Part #68039104aa $177 Cummins Dealer

335,000 Miles
*Replaced Alternator (Reman)
*Lights of my top 3 buttons on radio went out
*A/C Lights Broke
*Adjusted Valves (FIRST TIME) page 16 for before/after videos

336,000 Miles
*Replaced Exhaust manifold (my stupidity, not wear & tear)

345,000 Miles
*Replaced Turbo P2262 but Turbo is fine <---Link
*Fuel Pressure Sensor
*Rear Diff Speed Sensor
*Sway Bar End Links
*Rear Axle Driver Side Seal

365,000 Miles
*Replaced water pump
*Replaced all joints and carrier bearing in shaft, also rebalanced
*Replaced rear end, was on way of bombing (junkyard low mileage unit)
*FIRST TIME BELT REPLACEMENT, (dang water pump) Thanks forum member Bayou Hotshot for the help!!
390,000 Miles
*Both power steering pressure lines
*Power steering pump
*Exhaust Pressure Sensor #1 Exhaust brake malfunction help???? 400k miles <---Link

410,000 Miles
*Modded Raditor 6.7L Cummins Larger Capacity Radiator <---Link Mine didnt break, just wanted cooler temps

417,000 Miles
*Rear Main Seal/Sleeve
*Flexplate x2 (added BD flexplate) (USED PARTS SUCK SOMETIMES, HOPEFULLY!!!!)

------------------------------------------------------------------

Now,

PROBLEMS WITH TRANSMISSION BEFORE REPLACED
Here is the Scan tool readings when lost 5-6 in transmission..
SCAN TOOL READ:

stored clutch #s are as follows
OD=55
N-D=70
UD=55
4C=47
ALT 2C=69
L/R=87
3-4=63
N-D UD=94
2C=50
2-4=50

1-4 acts perfect, once it tries to go into 5th, it will grab for 1/2 sec then jump rpms then back down to grab for 1/2 sec, then repeat operation.
She still doesnt have 1 oil leak. Well, my rear end seal has a small leak. But thats all that is. Maybe 1 day I will fix my girls rear end but as of now, its fine.

"Not a bad list, huh!"


As far as maintaince goes

*Every 25,000 miles I wash air filter.
*Every 30,000 miles I change fuel filters.
*Every 30,000 miles I drain atf fluid.
*Every 30,000 - 40,000 miles I change oil and filters.
*Every 60, 000 miles I change atf filters.
*Every 100,000 miles I change pcv filter.
*Every 100,000 miles I change rear diff fluid.
*Every 100,000ish miles I replace batteries.
*Every 250,000 miles i replace coolant.

Running Stock Injectors.

I can only hope to manage half the miles and spend no more than that on repairs. I'd say, he has done gooood!

Actually if that's the one I'm thinking of it wasn't deleted...

Honestly, when both engines are running the same emissions system (cats, but no dpf, etc), they are both very reliable. My dad has a 05 5.9 and if we tow the same trailer with both trucks, I'll give the 6.7 the edge as it seems to have a little more down low. Plus the 6 speed auto and the engine brake is the icing on the cake for me.

I think it impossible to run 30-40,000 miles between oil and filter changes without this truck being deleted, I think you'd be lucky to get 3-4000 miles.

I kinda wondered about that, but he's hotshoting, so it's highway miles almost exclusivly. Those are easy miles, even towing.

Its those of us running 80% town and city service streets that are choking on their own exhaust. I spent 8 hours today running diliveries and put 150 miles on with the motor shut off twice. Hard for a motor with a cork in its tailpipe.

I don't know that I'd call them easy miles at over 30,000 gross. Easy with respect to keeping the DPF nice and hot if it's not deleted. Thirty to forty thousand miles between oil changes seems like an awful lot for even a deleted truck, but if true I won't argue with the results. I'd be happy to get 250,000 good miles. Sounds like the tranny could make it since I'm not towing anywhere near 30,000 and tranny temps stay 180 degrees or less.

I could see it with a bypass system, double filters and changing the filters regularly with Blackstone tests.

I look forward to seeing the oil after deletes.

Emission stuff doesn't cause as much detriment when working the engine. Causes more trouble with short trips empty and not up to full operating temp. My '03 5.9 takes awhile to warm up. Hook onto a trailer and she's happy. If you need a car get an ecoboost. I live 14 miles from town so when I have to use my truck to just haul kids it does get warmed up. Not sure if a 6.7 would get warm enough on that trip though.

T210DRVR, How did you get so many hours onto your truck? I check mine, my 2010 is 722hrs and 40000miles. My 02 might be 5000-6000hours.

Wow looking at your details, you actual did really well. No real failures issues early on. My 02 lost its first transmission at 6000miles.[laugh]