Community Forums

Road-Chi · 12-05-2024, 05:21 PM

We are considering buying at a coach with an ISX 600 engine. The coach has just over 70k miles on it and is in excellent condition, yet I've read about the problems and concerns with the ISX 600 and now wondering if such issues are applicable to this coach's specific engine.
I called Cummins with the engine number who said that that specific engine has both DPF and EGR; and that there has never been any recalls on the engine. Also, I am looking for advice as to concerns about buying the coach with the ISX 600.

d23haynes57 · 12-05-2024, 05:23 PM

What year? The ISX problems are mostly with the early twin cam non DPF/DEF engines.

Dieselboy · 12-05-2024, 05:34 PM

They’re right, there never has been a recall on the motor. Though they designed a whole new head with proper metallurgy in the valves that were failing and torpedoing engines.

Bet they didn’t tell you that, though. Many have recommended setting aside $25,000-$35,000 on a rebuild or getting a price reduction of that amount if it hasn’t had the new head installed.

d23haynes57 · 12-05-2024, 05:37 PM

Quote:

Originally Posted by Dieselboy

They’re right, there never has been a recall on the motor. Though they designed a whole new head with proper metallurgy in the valves that were failing and torpedoing engines.

Bet they didn’t tell you that, though. Many have recommended setting aside $25,000-$35,000 on a rebuild or getting a price reduction of that amount if it hasn’t had the new head installed.

And you sometimes see those engines used as late as 2012 models.

Road-Chi · 12-05-2024, 05:51 PM

It is a 2007. Any way to tell if the "fix" has been done?

vito.a · 12-05-2024, 06:13 PM

If you get the engine serial number you can have Cummins look up the repair history to see if the cylinder head has been replaced. But I doubt it has.

The ISX 600hp version is a great engine. Most of the issues are with the ISX 650hp dual overhead cam CM871 engine.
If you like the coach buy it and negotiate the price down $25k. Then you can have the cylinder head replaced or purchase an extended warranty.
Good luck!

d23haynes57 · 12-05-2024, 11:12 PM

Quote:

Originally Posted by Road-Chi

It is a 2007. Any way to tell if the "fix" has been done?

I would like to think that if a major repair or upgrade was done that would be presented as part of the sales offering. If it isn't documented, it wasn't done. Read the description in this ad as an example.

https://www.premierrvservices.com/20...affinity-45-2/

Melster · 12-06-2024, 12:11 AM

Have the ISX in my 2023 KW.
It pulls 105,500 lb loads 6 days a week!
No issues and average 5.7 mpg.
I run the snot out of it lugging it down to 1100 on hills, 2200 rpm on the Jake brake going down mountain passes.
Don’t worry about it!
Just run the ein thru Cummins!

jacwjames · 12-06-2024, 08:30 AM

Do a search for a Technical Service Bulletin concerning the valve/EGR issue and determine whether the 600HP is part it.

Cummins didn't do recalls on a lot of issues but did send out TSB's to service centers.
My coach had a TSB concerning the lift pump. Initially Cummins would change the pump out proactively but my guess it got too costly so they only addressed the issue if the customer complained/reported. In the end they didn't do anything, up to the customer to rectify.

Dieselboy · 12-06-2024, 12:02 PM

Quote:

Originally Posted by Melster

Have the ISX in my 2023 KW.
It pulls 105,500 lb loads 6 days a week!
No issues and average 5.7 mpg.
I run the snot out of it lugging it down to 1100 on hills, 2200 rpm on the Jake brake going down mountain passes.
Don’t worry about it!
Just run the ein thru Cummins!

I think this is the point, running these motors hard is the key to them avoiding the acid build up people claimed is the cause for the valve failure, which turns catastrophic when it goes. This is what I’ve read anyways. The new head has valves that hold up better to this acid in the system from the EGR system. It also has a redesigned coolant flow through the head. Again, this is what I’ve read about it.

Run the ISX hard, they’re designed to move 100,000lbs all day everyday. Our coaches they put them in are half that weight. And I try to never idle mine but for maybe two minutes if I just pull off the freeway. Otherwise it’s off if it’s not being driven.