During our research on "Buying a Diesel Pusher" we spoke with a number of coach owners who had opted for the new Cummins 8.3 litre 350 HP diesel engine. To our considerable surprise, we found what we considered an unexpectedly high rate of warranty claims due to engine malfunction. As a consequence, we decided to take advantage of resources at our own website to see if we could learn more. The following is a Q & A between RVers Online, and Josh Berman, our Online Advisor for matters pertaining to Cummins products.
QUESTION BY RVers ONLINE: Hi Josh, we've been doing some research on options for purchasing a new diesel pusher. In the course of doing so, we've spoken with a number of owners of the Cummins ISC 8.3 350 engine. Several have described problems which have required warranty service by Cummins. Could you let us know what the experience has been with this new engine, and to the extent problems have been detected, what steps Cummins has taken to correct the situation? Many thanks, Tom
ANSWER BY JOSH BERMAN ON BEHALF OF CUMMINS: Thanks for your note. The majority of the reliability problems with the ISC have been related to the fuel system. When we launched the ISC engine in March 1998, it was (and still is) equipped with an electronically controlled fuel pump designed and manufactured by Cummins. Soon after launch, we found that the Cummins fuel system had several problems that made it unreliable. These problems were primarily due to late design changes to some fuel system components, including the rate shape tube.
Obviously, this could not continue. We immediately dedicated several teams of engineers, assembly line workers, designers, and suppliers, to solving the problems. Unfortunately, while we were developing and testing solutions to some of the problems, customers frequently experienced multiple failures of the same parts. The failure rates of these parts, which was higher than we had predicted it would be, often made supplies of the parts very short, making it difficult for our distributors to get parts quickly. This sometimes resulted in extended down-time for the customer. These "main" failures were of the rate shape tube (which carries the high pressure fuel, at up to 15,000 psi, from the accumulator to the injection control valve) and bracket, and of the fittings on each end of the tube, were it attaches to the accumulator and the distributor.
However, by late 1998, our problem solving teams had identified, tested, and incorporated into both production and service, solutions for the major Cummins fuel system problems that we identified after the launch of the ISC. At that time, we also released a campaign, #9901, to proactively find and repair any ISC engine that did not yet have the new parts. Should an ISC (unfortunately) fail prior having the campaign 9901 parts installed, they are installed at that time.
The GOOD news is that except for two or three occurances related to improper installation, we are not aware of any campaign 9901 parts that have failed on engines.
That is by no means the end of the story. We are continuing to work on improving the reliabilty of both the Cummins fuel system and the engine. Much of this work has concentrated around sensor reliability, and we have implemented (and will be implementing in the near future), improvements to several different sensors. Since the failure rates of the sensors have not approached the failure rates of pre-campaign #9901 Cummins fuel systems, we have not campaigned the sensors, but instead install new sensors should the old ones fail.
I would happy to confirm that a customer's engine has had campaign 9901 performed on it... either the engine in their current coach, or an engine in a coach they're looking to purchase. If they haven't had it done, I can also help them arrange to have the campaign performed at a Cummins repair location. Just send me an email with your name, return email address, and your engine serial number. The campaign #9901 repairs are, of course, performed free of charge.
Joshua Berman MidRange Service Cummins Engine Company
Cummins Homepage: www.cummins.com
EDITOR'S NOTE: We appreciate this helpful response on behalf of Cummins. We've previously owned two of the 5.9 litre Cummins diesels, and we've personally found them highly reliable. The issue with the new 8.3 litre Cummins 350 diesel was undoubtedly a source of some frustration to RV owners who had to seek relief under warranty. However, we think it's interesting to note that Cummins has not only confirmed the problem, but has made considerable efforts to fix it. We appreciate Josh's offer to help owners identify whether a Cummins ISC 8.3 engine they own, or may contemplate purchasing, has had the "campaign 9901 fix". The remedial action Cummins has taken here only confirms our personal opinion that this is a company committed to customer support. This conclusion seems justified as well lby the very fact that Cummins has volunteered to have an "Online Advisor" to support the efforts of RVers Online to provide quality support and information for our readers. We would welcome the participation of RV manufacturers in a similar capacity.