ISX 600 HP Cummins engine pros or cons

My 2007 Coach with a 2006 ISX, EGR but not DPF, has 83,000 miles and running strong.

Who knows what lurks inside any engine. There have been some valve corrosion problems reported. I'm waiting for Lvylog to drill and report.

Some are working the purchase deal to allow them to replace the head pre-emptively sharing the cost with the seller.

Run unless you can buy the 2006 Signature with a ISX 600 for less than $100K. A 06 Sig with a Detroit for $130K, yes. I paid $165K for my 08 Navigator a year ago.

Johnny G1 wrote:
Its in just about every truck on the road that is pulling heavy loads, so can't be much wrong with it.Definately not needed in a 50,000 lb mh.

Yeah, but it is sure nice to be able to pull out and go around up hill traffic any time you choose.

ISX cummins dependable as it gets. and probably just passed its second oil and filter change.

The good news is it’s not a 2007 or later ISX...I made sure my 08 Navigator had a 2006 engine, BUT I was not aware of the following problem. On another forum there is a lot more info on the ISX dropping the #6 intake valve to the tune of $30K in repairs. No good reason why and it’s more with the 600/650HP engines and 07 and later. More info here: ISX #6 valve breaking Some think it’s the gasses from the EGR that weakens the stem of the valve but why is it only #6 and mainly in MHs and not often in trucks?

My ISX is a 525 HP with 47K miles and I may drill a hole opposite the #6 in the intake manifold to look at the stem of that valve. If it is pitted (hopefully not) there are new valves and seats for the ISX but you are still looking at $20K+ to install.

I had to have a 08 MH because of a 10 year rule where we snowbird and Monaco did not make any 08s with the Detroit 60 engine. I would only buy a big Monaco with a Detroit 515 HP engine. Too many expensive unknowns with a ISX, especially the higher HP engines.

Its in just about every truck on the road that is pulling heavy loads, so can't be much wrong with it.Definately not needed in a 50,000 lb mh.