FYI Good article on DEF head failures

[TJ&LadyDi]

I wander if the military diesel vehicles are under the same EPA air pollution rules like the civilian ones? It will make them less reliable in combat if they are using the same DEF equipment.

My guess is that military vehicles don’t use DEF at all; just one more thing that would have to be delivered to the battlefield.

TJ

 

[Just George]

Has anyone found info on DEF failures in the trucking industry? My thinking is there must be other engine manufactures in trucks running a lot of miles. So if there is failure info it would be interesting to see if they all (or majority) are associated with a Cummins engine or if the def failure issue is affecting others equally. If the commercial trucking failures are heavily weighted to configurations with Cummins engines then perhaps some focus on trying to get Cummins to engage for some help would be in order.

 

[Neal]

I'd love to see real numbers, not sentiment or emotional analytics.

 

[TJ&LadyDi]

I just did some research on trucks having DEF head problems and found very little information. It doesn’t seem like many truckers are having this issue or, at least, are not posting comments about it.

Interestingly enough, I found quite a number of different trucker posts extolling the Cummins ISX engines as being pretty trouble-free. Many of these guys are running them for 500K to 1M miles plus without complaint. That doesn’t seem to be true for motorhome drivers, however! So, are we (a) not taking proper care of our Cummins engines, (b) more prone to worry about and comment on DEF head issues, or (c) both of the foregoing? Hard to know.

It does seem that the DEF head problem is a bigger issue for us motorhomers than it is for truckers. Could if be simply that Cummins is prioritizing trucks in the parts supply chain because they are considered an essential part of the commerce system? Who knows? My guess, however, is that if you are a big OTR truck outfit, a way will be found to get you the parts needed to keep your trucks running.

Nothing earth-shattering here, but the bottom line seems to be that we’re hearing a lot more about DEF head failures in the motorhome community than are being heard in the OTR truck industry.

TJ

 

[Neal]

I tried finding info too and was unable. But let's step back for a minute and realize some major differences. Truckers have engines in the front with high airflow and front mounted radiators. I assume their DEF and after treatment configurations are also up front with ample cooling. Motorhomes have the engines rear mounted with much poorer airflow and cooling. When I was at Cummins (Tucson) I asked about the different motorhome engines and their reliability, the guy said the 605's run very hot which can be problematic. Just not enough cooling for them. Now let me discount that statement with the very same situation we get with asking "techs" about tire pressure, etc. - we get opinions and a gazillion answers, so who knows what to believe. But I digress, let's keep in mind huge differences between motorhomes and truckers - engine location and cooling of the components.

 

[redbaron]

The theory that I have seen others discussing is that temp has nothing to do with the real issue. Instead, the amonia created by temp is causing the shaw (and other) sensors glue to fail, allowing the sensor to become compromised. The failure is the sensor assembly itself, causing the sensor to fail. Once the sensor fails, the report will be one of the data points reported by the sensor, or all of them...temp, quality, quantity. This will cause a derate.

Replacing the sensor, and making no other changes will resolve the issue. No need to regen. No need to drain/fill. No need to do anything other than send good signals.

 

["EZ"]

I wander if the military diesel vehicles are under the same EPA air pollution rules like the civilian ones? It will make them less reliable in combat if they are using the same DEF equipment.

They are exempt. Or at least they were.............

 

[Rich-MLsRV]

RVtravel.com posted an update - Stranded due to DEF head? New developments and a possible workaround.

 

[Neal]

Interesting revision. I don't think getting some EPA approval and a bypass is the long term fix, or any fix for that matter. This sounds like an engineering and design problem for those experiencing this more than others. "Crane Man" in the 2-3 paragraphs outlined some probable causes which I hope will gain attention that this could be a problem caused by a poor design by a vendor instead of the system itself.

 

[Sonic]

I would classify a valve that’s “prone to stick” as a substandard implementation of the Cummins design. Asking Cummins to develop a software patch and install it on potentially hundreds of thousands of vehicles isn’t the right approach, and I can’t blame them for resisting. It sounds like chassis manufacturers need to pressure their vendors to implement more robust solutions, then issue a recall to replace these potentially problematic units.
Interestingly I read a comment from the CEO of NIRVC who did a parts search across all of his service departments nationwide, and found 65 DEF Head assemblies ordered over an 18 month period. 64 were for Spartan chassis, 1 for Freightliner (they use different vendors for their DEF head assemblies)
That’s just one data point but it would be interesting to see if it would hold up across all service centers.