Cummins ISX 650 HP Engine Valve Issue?

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DaddyDe

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Nov 17, 2018
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Lake Creek Ranch, Idaho
I am looking into purchasing a 2012 Monaco Dynasty Palace IV motorhome that has a Cummins ISX 650 HP Diesel engine...  Reportedly Monaco only manufactured 18 of those units with the 650 HP Cummins Diesel engine. In subsequent years it appears that they went to the 600 HP engine or smaller...  One person in the Forum Community advised that they had heard that the engine has/had a valve problem that can be very expensive to repair.  They had also heard that there might be some type of an upgrade kit that could prevent the failure from happening...  In searching through the existing threads on this forum one other discussion regarding extended warranty mentioned a Cummins ISX 650 Hp engine in a Winnebago that had a valve issue on cylinder #6 that cost $38,000 to repair.  I could not locate any reference to an available upgrade option to prevent the issue.  Is anyone familiar of the issue with the valves on this engine or the upgrade options?  Thank you in advance for your assistance / guidance.
De
 

Gary RV_Wizard

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I've been hearing about this ISX valve problem kately.  From what I understand, the dual overhead cam version of that engine is known for "eating" the #6 valve, to the tune of $30k or more.  Cummins blames it on inadequate maintenance, but they changed the engine design after a year or two of production.  The current ISX is a different engine, with a single overhead cam.  As I understand it, the single overhead cam version came out in 2010, to meet the EPA 2010 requirements.

There have been multiple reports of this failure on the American Coach Owners Group, where the ISX was also widely used on the larger coaches, e.g. Heritage or Eagle 45's.  One of the coach owners has a commercial trucking business and every one of his ISX enginess experienced the problem.

I'm not sure that the horsepower rating is the criteria for good or bad - think it is dual cam vs single cam. Suggest you call Cummins and ask about that particular engine. Have the Engine Serial Number handy, cause the coach model year can be way off from the engine build date.  A 2012 should have the single cam engine, but maybe there were still some new dual cam ISX waiting toi be installed.
 

DaddyDe

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Joined
Nov 17, 2018
Posts
8
Location
Lake Creek Ranch, Idaho
@Gary RV_Wizard
Thank you very much for your response and information.  We Definitely appreciate it...  I will get the serial number and contact Cummins to see if they can shed any light on the situation...
Thanks again, De
 

Gary RV_Wizard

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If it's the single cam engine, I think it is safe. If the dual cam, from what I read either the 600 or 650 can have the #6 valve failure, but the 650 is more prone than the 600. The ISX also comes in other lower hp ratings, but they are not found in motorhomes.
 
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