Difference Between 2006 ISX and 2007-2009

[LOUISIANA]

I am in the market for a used diesel pusher and Country Coach is my preference, but I am spooked by what I have read here and heard about in my search.

From what I have read, the 2007-2009, 600 and 650 HP ISX are the problematic engines with the 650 HP being worse. How about pre 2007, namely 2006 ISX's and 2006-2007 Cat C-13's??

[Mark D]

I have a 2011 coach with a 650 ISX built in late 2009. I read a few blurbs about valave issues. I called Cummins and they said all mechanical items i.e. valve train are the same across all HP range. I also called the place we get service done, they do mostly trucks. I asked about issues with the ISX. The only gripe they have heard was that the maintenance is more for an ISX than other ones. That means you need a major maintenance at 250k miles.

I can say that mine runs great, eats hills like nothing. Set the CC to 65 and it won't slow it just makes a rumble and off it goes.

I think the issue with the ISX that have a valve issue is a problem in a casting for the valve train. I did buy a 5 year 60k mile warrantee that covers most everything even wear and tear non cosmetic. So if the engine did go It would be covered.

But think about it Cummins made thousands of these engines maybe tens of thousands so if it was a common thing the truckers would have a huge gripe besides the 250k maintenance.

The 3 stage engine brake is awesome also.

[Steve Ownby]

Originally Posted by LOUISIANA

I am in the market for a used diesel pusher and Country Coach is my preference, but I am spooked by what I have read here and heard about in my search.



From what I have read, the 2007-2009, 600 and 650 HP ISX are the problematic engines with the 650 HP being worse. How about pre 2007, namely 2006 ISX's and 2006-2007 Cat C-13's??

From all the posting concerning this issue, the DOHC design engines were problematic when rated at or above 600 hp. The SOHC design which appeared around 2010 seems to have resolved the issue. It appears that the trucking industry had few problems with the ISX but they mostly use engines rated below 600 hp.

[LOUISIANA]

I spoke with a few technicians at the Cummings place as well and I think a big part of the problem is that these engines are not driven in motorhomes often enough. They tell me that it creates moisture letting them sit which turns acidic and starts to erode the #6 valve and piston. That the number six valve/piston is in the back where the heat is the highest and seems to cause the problem. They also told me that idling a diesel engine is terrible as it creates soot which clogs everything up and that starting an engine without warming it up also creates soot. They recommended a coolant heater which would pre-warn the engine and said that this coolant heater could potentially decrease moisture build up if the engine was allowed to set up.

[LOUISIANA]

Originally Posted by Steve Ownby

From all the posting concerning this issue, the DOHC design engines were problematic when rated at or above 600 hp. The SOHC design which appeared around 2010 seems to have resolved the issue. It appears that the trucking industry had few problems with the ISX but they mostly use engines rated below 600 hp.

OK, great, that’s what I was looking for. In summary ISXunder 600 hp is reliable with 600 being less reliable and 650 horse power being the worst.

Correct me if I’m wrong, but the 2006 Cummings engine is not a dual overhead cam engine and therefore more reliable than an ISX 600-650 hp?

[A Traveler]

It’s CUMMINS, not CUMMINGS. There is no “G” in the company name.

[Mr_D]

Check the Cummins site, they have the lineage of the various ISX's.
The 2010 EPA version is a SOHC design, haven't bothered to look up the earlier than 2007 version since mine is the 2007 650 hp CM871 version.
WIKI says the ISX replaced the m14 in 2002 and was a DOHC until the 2010 version went to a SOHC design.
Pictures of a 2003 ISX show it to be a DOHC.

[LOUISIANA]

Originally Posted by Mr_D

Check the Cummins site, they have the lineage of the various ISX's.
The 2010 EPA version is a SOHC design, haven't bothered to look up the earlier than 2007 version since mine is the 2007 650 hp CM871 version.
WIKI says the ISX replaced the m14 in 2002 and was a DOHC until the 2010 version went to a SOHC design.
Pictures of a 2003 ISX show it to be a DOHC.

By the way Mr D, my favorite prospect is a 2009 Donatello which was rebuilt because it had a knock (engine miss) from a lack of fuel in the cylinder which caused it to overheat. Cylinder 3 was the only one affected. A cracked head partially melted the injector. A new turbo, head, and DPF was installed, so I am faced with buying this beautiful coach or opting for another CC with a Cat , ISX under 600 hp or a pre 2007 ISX. For me this is the ~$200,000 question?

Correct me if I am wrong, but I have not read of any of these problems pre 2007 even though they are apparently DOHC. From my reading, it appears the introduction of the EGR and DPF that has caused the problems.

For those with interest and experience, I have posted potentially helpful links below:


file:///U:/My%20Documents/Home/Motor...ge%20Board.pdf

file:///U:/My%20Documents/Home/Motor...2%20Forums.pdf

file:///U:/My%20Documents/Home/Motor...ngInfo.com.pdf

[RVNewbie55]

Originally Posted by Mark D

I have a 2011 coach with a 650 ISX built in late 2009. I read a few blurbs about valave issues. I called Cummins and they said all mechanical items i.e. valve train are the same across all HP range. I also called the place we get service done, they do mostly trucks. I asked about issues with the ISX. The only gripe they have heard was that the maintenance is more for an ISX than other ones. That means you need a major maintenance at 250k miles.

I can say that mine runs great, eats hills like nothing. Set the CC to 65 and it won't slow it just makes a rumble and off it goes.

I think the issue with the ISX that have a valve issue is a problem in a casting for the valve train. I did buy a 5 year 60k mile warrantee that covers most everything even wear and tear non cosmetic. So if the engine did go It would be covered.

But think about it Cummins made thousands of these engines maybe tens of thousands so if it was a common thing the truckers would have a huge gripe besides the 250k maintenance.

The 3 stage engine brake is awesome also.

Totally agree. Just turned 37,000 on ours. Zero issues, but also purchased a high end warranty. Installed the Ugly Fix about 5,000 miles ago and have even seen a 1/2+ increase in mpg. can't help but smile when cresting a hill at the same speed I started up it at. And our toad is a little over 5,000 lbs

[2-Nickels]

I bought a 2009 CC knowing the ISX was a problem in this year but was fixable. I offered for the coach 30K less than they asked and then some knowing batteries and tires were due as well. The seller accepted. The first stop was Cummins, they tore it down and rebuilt it. No troubles since, 1 year ago and 10K miles. I wouldn’t be fearful but rather cautious and do what you know is right.

[LOUISIANA]

Thanks for all the great advice. What is the fix for the ISX? What warranty do you all recommend?

Also, can any good motorhome repair place work on The house on these country coaches, or is it important to bring it to Oregon or I understand there’s a place in Illinois?

Has anyone bypassed the EGR or removed the DPF and related “stuff” or known anyone who has (eye winking) and if so, what has been your/their experience?

[Mark D]

Originally Posted by LOUISIANA

Thanks for all the great advice. What is the fix for the ISX? What warranty do you all recommend?

Also, can any good motorhome repair place work on The house on these country coaches, or is it important to bring it to Oregon or I understand there’s a place in Illinois?

Has anyone bypassed the EGR or removed the DPF and related “stuff” or known anyone who has (eye winking) and if so, what has been your/their experience?

I purchased an Eagle plan from US Warranty. Itvwas the most comprehensive plan that even covers wear and tear mechanical items as well as incidental issues.

I was on the fence at first thinking save the money to one side etc. I purchased it as a piece of mind plan.

In the end it will cost me $165 +/- per month.

[Mr_D]

Originally Posted by RVNewbie55

Totally agree. Just turned 37,000 on ours. Zero issues, but also purchased a high end warranty. Installed the Ugly Fix about 5,000 miles ago and have even seen a 1/2+ increase in mpg. can't help but smile when cresting a hill at the same speed I started up it at. And our toad is a little over 5,000 lbs

I installed The Ugly Fix last year. Can't confirm any mileage gain but do know I didn't lose any.

[Mr_D]

Originally Posted by LOUISIANA

Thanks for all the great advice. What is the fix for the ISX? What warranty do you all recommend?

Also, can any good motorhome repair place work on The house on these country coaches, or is it important to bring it to Oregon or I understand there’s a place in Illinois?

Has anyone bypassed the EGR or removed the DPF and related “stuff” or known anyone who has (eye winking) and if so, what has been your/their experience?

Any shop can work on them, BUT there are some unique features that take longer to even find the circuitry. Lots of stuff behind panels.
I burned out a fuse replacing the halogen map light with LED over the passenger seat Took me a lot of head scratching and looking at the electrical layout to find the fuse in the closet at the back of the rig behind a decorative panel some 40' away.
When the engine blew they charged me $4,500 to take out and replace the bedroom panels to get to the top end. I did it myself in a couple hours when trying to install The Ugly Fix. Turned out I didn't need to get to the top of the engine, just the side.
The Ugly Fix doesn't remove any of the smog stuff, it just fools the system into thinking you're above 7,000 ft elevation and keeps the EGR valve closed. On my rig it's a 5 min job to replace it with the OEM sensor if the engine is cold.