Nothing but short trips in 6.7 diesel

[NorthwestGuy]

I've only got 2100 miles on the truck and haven't had the opportunity to do any heavy hauling or make any kind of lengthy trip more than 20-30 minutes. I heard somewhere these engines don't like that. Can anyone explain why, and what I need to do?

 

[GunnerJ]

I dont know how the new DEF equipped 6.7s handle it but on trucks like mine (pre DEF 2011) they had to go into regen mode to clear out the DPF filter. The other big thing it soot caking in the turbo making the VGT not work, which also means you no longer have an exhaust brake. So to combat that, always have your exhaust brake on so the vanes on the turbo are always moving and can never get coked up

Sent from my SM-G960U using Tapatalk

 

[MADDOG]

As Gunnerj notes, a good long trip to warm up all the systems, especially the DPF converter, keeps the trapped soot from damaging sensors and other components.

 

[Arth]

I've only got 2100 miles on the truck and haven't had the opportunity to do any heavy hauling or make any kind of lengthy trip more than 20-30 minutes. I heard somewhere these engines don't like that. Can anyone explain why, and what I need to do?

Not so much the engine as much the emissions equipment. You'll eventually see this I think.

 

[NorthwestGuy]

I dont know how the new DEF equipped 6.7s handle it but on trucks like mine (pre DEF 2011) they had to go into regen mode to clear out the DPF filter. The other big thing it soot caking in the turbo making the VGT not work, which also means you no longer have an exhaust brake. So to combat that, always have your exhaust brake on so the vanes on the turbo are always moving and can never get coked up

Sent from my SM-G960U using Tapatalk

I do have my automatic exhaust brake on all the time so I've got that part covered.

 

[NorthwestGuy]

As Gunnerj notes, a good long trip to warm up all the systems, especially the DPF converter, keeps the trapped soot from damaging sensors and other components.

Can you give me an idea how often that should be done, and how long is long enough?

 

[MADDOG]

Depends on how much you idle or how long the short trips are.

I'd suggest a 30 minute trip on a highway at freeway speed to "blow it out" once a month. That should be more than enough unless your truck sits and idles for hours on end.

 

[NorthwestGuy]

Depends on how much you idle or how long the short trips are.

I'd suggest a 30 minute trip on a highway at freeway speed to "blow it out" once a month. That should be more than enough unless your truck sits and idles for hours on end.

Thanks, I'm starting to learn about the DPF and how regeneration works and I think I'm getting the gist of it. Once in a while I've just got to start driving to the next town up the road past where I usually go to blow out that filter and try not to idle any more than necessary.

 

[MADDOG]

That's about the gist of it all right.

Mine was so problematic that even long trips in high temps still didn't eliminate the regen failure problem.

So now I don't have a DPF system, a DEF tank, an EGR cooler or throttle valve, the DPF catalyst chamber is gone and so is the regen can.

 

[mtnrider]

I have gauges set up to monitor when regens occur, what type of driving causes them to occur more frequently etc. EGT's, Differential pressure across the DPF (what it judges a regen on), how many miles between regens

I can say based on my hard data that short trips, idling (short periods, not all day long) are no worse then long highway drives. The advice of "run it hard or long on the highway" does nothing but burn more fuel and make the problem worse. The truth is unless you are hauling a heavy load the EGT's simply do not get hot enough to burn off the soot in the DPF.
In fact the worse thing you can do is go out on the highway and hammer on it with out a load. You are just dumping more fuel in which creates more soot and never getting hot enough to burn it off.

If the system is working as designed it will simply regen and burn off the soot as needed so nothing to worry about. Obviously there are some trucks that don't work as they should and have issues but honestly they are few and far between

Just drive it and don't worry about it

.

 

[NorthwestGuy]

I have gauges set up to monitor when regens occur, what type of driving causes them to occur more frequently etc. EGT's, Differential pressure across the DPF (what it judges a regen on), how many miles between regens

I can say based on my hard data that short trips, idling (short periods, not all day long) are no worse then long highway drives. The advice of "run it hard or long on the highway" does nothing but burn more fuel and make the problem worse. The truth is unless you are hauling a heavy load the EGT's simply do not get hot enough to burn off the soot in the DPF.
In fact the worse thing you can do is go out on the highway and hammer on it with out a load. You are just dumping more fuel in which creates more soot and never getting hot enough to burn it off.

If the system is working as designed it will simply regen and burn off the soot as needed so nothing to worry about. Obviously there are some trucks that don't work as they should and have issues but honestly they are few and far between

Just drive it and don't worry about it

.

Well, I just got my hands on the Cummins diesel supplement that they failed to give me with the truck. It says that the REMEDY for a clogged filter is to drive it at highway speed for about 20 minutes. Doesn't say anything about doing it under load. Why would they recommend doing this if the exhaust temps don't get hot enough to do any good? I'm not discounting the possibility that you could be right but this seems like a discrepancy from what you are saying. Here is the text:

"Under conditions of exclusive short duration and low speed
driving cycles, your diesel engine and exhaust after treatment
system may never reach the conditions required
to cleanse the filter to remove the trapped PM. If
this occurs, the “Exhaust Filter XX% Full Safely Drive at
Highway Speeds to Remedy” message will be displayed
in the instrument cluster display. If this message is
displayed, you will hear one chime to assist in alerting
you of this condition. By simply driving your vehicle at
highway speeds for up to 20 minutes, you can remedy
the condition in the particulate filter system and allow
your diesel engine and exhaust after-treatment system to
cleanse the filter to remove the trapped PM and restore
the system to normal operating condition."

 

[mtnrider]

Well, I just got my hands on the Cummins diesel supplement that they failed to give me with the truck. It says that the REMEDY for a clogged filter is to drive it at highway speed for about 20 minutes. Doesn't say anything about doing it under load. Why would they recommend doing this if the exhaust temps don't get hot enough to do any good? I'm not discounting the possibility that you could be right but this seems like a discrepancy from what you are saying. Here is the text:

"Under conditions of exclusive short duration and low speed
driving cycles, your diesel engine and exhaust after treatment
system may never reach the conditions required
to cleanse the filter to remove the trapped PM. If
this occurs, the “Exhaust Filter XX% Full Safely Drive at
Highway Speeds to Remedy” message will be displayed
in the instrument cluster display. If this message is
displayed, you will hear one chime to assist in alerting
you of this condition. By simply driving your vehicle at
highway speeds for up to 20 minutes, you can remedy
the condition in the particulate filter system and allow
your diesel engine and exhaust after-treatment system to
cleanse the filter to remove the trapped PM and restore
the system to normal operating condition."

I can tell you at the company I work for the guys writing manuals are not the engineers that designed the products.

The real data I am seeing says the EGT's simply do not get hot enough to start burning off the soot. They need to be up around 980-1K degrees before I start seeing a reduction in the differential pressure across the DPF. Highway driving with no load I barley get over 800 degrees so it is not burning anything off and I can watch the gauge continue to climb (soot building up).


At the end of the day it's your truck so do as you see fit. I was just passing on the info I see the truck doing real time. I always thought running on the highway was the answer as well and was surprised to see that it wasn't doing anything. Maybe if you took an 8 hour highway trip it might get hotter? Haven't taken it more then about 1 1/2 hours since I set up the gauges.

.

 

[hounddog]

RAM CTD uses the first 3,000 miles to final polish the inside of the engine. It's best to pull something heavy as much as you can during that period, and RAM strongly recommends it, but I don't think it'll hurt the engine if you cant.

According to my mechanic run the exhaust brake on full ALL THE TIME, try to keep driving RPMs at least 1,500 and don't let it idle for extended periods all because of turbo sooting- especially in cold weather because the cylinders need to maintain temperature and you can cause something called caramelization if the cylinder temps drop below proper internal temperature and that's bad.

 

[crash68]

don't let it idle for extended periods all because of turbo sooting- especially in cold weather because the cylinders need to maintain temperature and you can cause something called caramelization if the cylinder temps drop below proper internal temperature and that's bad.

I think the condition your referring to is called wet stacking. That is when the cylider combustion temperature is not warm enough to burn off all the fuel and it goes out the exhaust and washes past the piston rings into the crankcase.

 

[NorthwestGuy]

RAM CTD uses the first 3,000 miles to final polish the inside of the engine. It's best to pull something heavy as much as you can during that period, and RAM strongly recommends it, but I don't think it'll hurt the engine if you cant.

According to my mechanic run the exhaust brake on full ALL THE TIME, try to keep driving RPMs at least 1,500 and don't let it idle for extended periods all because of turbo sooting- especially in cold weather because the cylinders need to maintain temperature and you can cause something called caramelization if the cylinder temps drop below proper internal temperature and that's bad.

"It's best to pull something heavy as much as you can during that period, and RAM strongly recommends it,"
If they strongly recommend this it must be written somewhere. Where would I find this?

 

[Hd74ica]

I've had 4 diesels, 2 of them had the emissions and nothing but problems . Operator error, I didn't work them hard enough. Moved to the 6.4 and now happy.

 

[SETEX 6.4]

I sure love my 6.4 Hemi. It may only get 10mpg but dammit I can always just git in it and go. Never have to worry about if I'm getting my EGT up hot enough.

2014 Ram 2500 Mega Cab 6.4 Hemi 4:10 Gears Ram Boxes 35x12.50R18 on Factory Wheels
Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[hounddog]

"It's best to pull something heavy as much as you can during that period, and RAM strongly recommends it,"
If they strongly recommend this it must be written somewhere. Where would I find this?

The diesel appendix section. Spells it out in black and white.

I'm out on a transfer from boat dealership to dealership now, when I get home tonight later I'll s3e if I can find my manual and snap a photo.

 

[hounddog]

I think the condition your referring to is called wet stacking. That is when the cylider combustion temperature is not warm enough to burn off all the fuel and it goes out the exhaust and washes past the piston rings into the crankcase.

Chrysler mechanic calls it carmalization, but yes. It also causes in cylinder fuel to harden into a caramel like substance clogging everything.

 

[tourrider]

I stumbled across this a couple of days ago. Worth a look.