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Fleet Management Information for Sweeping Professionals

Contractors Report Isuzu DPF System Troubles

by Ranger Kidwell-Ross

In 2014 the World Sweeper office received a number of reports from parking lot sweeping contractors concerning trouble they were having with the DPF systems on their Isuzu chassis. As a result, we distributed a query to members of the World Sweeping Association. This informal survey resulted in more contractors coming forward with their experiences on the topic.

DPF Filter We have contacted Isuzu and provided the company representatives with the information. In this first of two stories, we have detailed the experiences of several of the contractors. Included mid-way are some informal comments by one of Isuzu's regional managers who has long worked with sweeper manufacturers, Victory Sweepers, Inc. and Schwarze Industries, Inc.

We also offer a follow-up story in this series, which is an article based upon a conversation with Mike Rossetti, Isuzu Commercial Truck's Director of Field Operations for the company, with additional comments by Jim Barnes, who is Manager of Regional Fleet Sales. The second story includes an approximately 35-minute audio podcast between Rossetti and the author. To get the most out of the issue, we suggest you read this article in its entirety before reading the Isuzu response.

A similarity with the reports we've fielded is that all involve parking area sweepers; to date, no street-class sweeper chassis problems have been reported with the exception of one contractor you will read about that has TYMCO 435 models. However, that contractor uses his machines for parking area sweeping. This would seem to imply that the slow speed of parking area sweeping may play a part in the DPF system failures.

Here's what the first contractor who contacted us had to say: "...Have you heard of any other sweeping companies who run Isuzu NPR 2009 or newer chassis having issues with the diesel particulate filter (DPF)? We have three and each one is doing the same thing. [The chassis] dies on the side of the road with no warning.

"I am told by my diesel delivery company rep that he is seeing this happening in trucks and that Cummins even has a recall on their system. (Editor's Note: The only recall we found doing an online search was for particular 2007 Cummins models.)

"We have checked the sulfur PPM, which is between 11 and 14.5, and the bio fuel is less than 5 ppm. [Our diesel supplier] believes it is the bio fuels that may be causing this issue. If that's the case, Isuzu should recall this because all diesel has bio mixed in it as well as sulfur. According to the filter specs the PPM has to be less than 15 but I am not sure about the bio side of it.

"I do not know if the people who designed this system counted on bio being mixed in the diesel or what impact it would have on the system... to repair this system ranges between $3000 to $8000 per sweeper. Makes one wonder: Are we saving the environment or are we making someone some money for a failed system?"

Have you had unusual trouble with your DPF system? If so, let us know your story.

Another contractor who reported DPF clogging trouble with several of the Isuzu chassis in his fleet said his dealer told him that the chassis had "no business having a slow-moving parking lot sweeper on it. A sweeper doesn't move with enough speed to keep the DPF system operational."

During the investigation process, and while going through the issue with Isuzu, that company's long-time regional manager, James Barnes, offered the following:

Isuzu LogoThe problem is that nobody ever explains to the owners/drivers that there is a manual regeneration button that the driver can push to keep the truck from going into "limp mode." You are correct that, many times, sweepers do not operate long enough at highway speeds for the regeneration system to heat up enough for the system to burn off the particulate matter that eventually clogs up the DPF.

That is where the manual system must be used by the driver. There are 4 stages of warning lights and the last stage is a 5 mph limp mode. Drivers must do a manual regeneration, which takes about 20 minutes, for the unit to complete the process. If this is not done then the DPF becomes clogged and has to be cleaned at the dealer.

Please remind your readers [who use Isuzu chassis] that the process is outlined in three places:

  1. Step-by-step details of the manual regeneration process is on a chart above the driver's sun visor
  2. The owner's manual also outlines the process
  3. There is a CD in every Isuzu chassis that the driver can listen to.

If you want to have this customer call me I don't mind a bit. I'll be glad to talk to him because I've heard of many people in his situation.

Barnes also said in an email that operators may be ignoring regeneration notices, which of course would make the problem worse. However, Barnes' tips about manual regeneration may not be the cure. The following are excerpts of some of the comments another contractor provided about his 2009 Isuzu chassis that is coupled with a Silent Knight sweeper:

"My crews run a manual re-generation [of the DPF system] at the end of each shift to prevent this problem. We have made this part of their daily routine to ensure we get full regenerations each shift but... our DPF continues to clog up and the costs keep coming.

"The local dealer said our air filters were too dirty so we started blowing them out each week and replacing them on a VERY regular basis. We were going through a lot of injectors as well. They said that was from fuel filters not having a better micron rating, alhough we were using what is specified for the vehicle.

[This truck chassis] "has really been a nightmare; I was so proud as this was the first brand new cabover truck my company had bought. It has turned out to cost me much more per day to run that all of my other (old) trucks combined. It has become obvious that parking this truck is better for me than trying to keep it running.

"The warranty has now ended, but Isuzu really never repaired much if anything under warranty; when it was under warranty I spent a fortune on it. I had to have the filter removed, sent off for cleaning and then installed back and that's not a warranty item, as just one example. Isuzu considers this to be regular maintenance even though [with this truck] it's been constant.

"The best I can tell after all I've gone through is that these trucks DO NOT work with sweepers on them. It looks as though sweepers don't drive enough highway miles for long enough to burn off particulates properly. If that's the case, then Isuzu should NOT sell them to sweeping companies!

"I have a TON of emails on this issue with Isuzu and the local distributor and I have a TON of money wrapped up into my truck. I have fought this issue and this truck and gave up 2 years ago. Only because you asked if others have this problem is the only reason I am breathing air into this nightmare situation surrounding this Isuzu truck of mine."

Finally, here's what a Texas-based contractor explained about his vehicles: "In 2010, I bought the truck brand new with a TYMCO sweeper on it. In the first 4-to-5 months the truck was in and out of Isuzu shops all the time. I took it to dealers in three different locations, Dallas, Texarcana and Waco, in order to try to find a solution to the DPF system fouling out.

"We kept taking it to Isuzu warranty technicians and they'd replace some part and we'd often not even be able to go 60 miles before the engine would quit. This happened repeatedly over the course of six months.

"The diagnostics kept showing different things to be wrong. The technicians couldn't put their fingers on what was wrong. One time they replace the mass air system; then they changed two injectors. Next was the turbo and then the PDF filter itself. I think after that it was a couple of sensors downline from the fuel pump. They kept addressing symptoms but couldn't locate any cause.

"Long story short, after we replaced injectors, turbos and everything else in the system, it was discovered that the problem was that it had the wrong oil dipstick. This wasn't discovered until I opened a formal complaint in the Isuzu system. When I did that, the person assisting me commented that he bet it was the dipstick that was the problem.

"These newer Isuzu chassis with DPF no longer have any type of 'road draft' ventilation of engine gases to the ground. Now, those types of emissions are re-directed back through the engine.

"The dipstick is what indicates that the right amount of oil has been put into the engine. The dipstick that had been installed with my engine was wrong. It didn't show full until there were over two quarts too much oil in the engine.

"As a result of having too much oil in place all the time, pure oil was being dumped back into the engine's system.That was overloading every component; fouling injectors, turbos and the DPF filtration system, since the system is not capable of atomizing oil.

"After all these months of trying unsuccessfully to get the engine fixed before finding the solution, we had to replace a couple more injectors and Isuzu told me that was my problem, not theirs. Then, the number three injector and number four roller bearing went out on the engine when it only had about 175,000 miles on it. The whole engine had to be replaced to the tune of $13,000.

I have six sweepers on Isuzu chassis but will not buy another one on that chassis after the company refused to even meet me halfway when my engine went down after all the trouble we'd documented. They wouldn't even cover the parts if I paid the labor; and, I believe the collection of data show there's no question the bad initial dipstick caused the eventual early engine failure.

"Although International chassis are now available, the International is a bit wider, just enough so to keep the 435 from going between parked cars in a standard store parking lot. This is a real issue when you're sweeping stores that are open 24/7."

By the way, instigating a formal complaint must be done with your Isuzu dealer of record; i.e., the dealership that has your initial warranty paperwork. If you know to ask, any Isuzu truck dealer can point you in the right direction.

If your organization has had similar issues with the newer Isuzu chassis, be sure to let us know so we can add them to our documentation.

Click to read and listen to the Isuzu response.

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