Cornerstone Overheating Issues

[P&GD]

We purchased our Cornerstone in February. In April we took the coach on a "shakedown" out to New Mexico through the southern U.S. We encountered our first Check Engine Light (CEL) in Texas, where we had the cooling system checked out -- no apparent issues. Since then, we've been experiencing recurring CEL's related to engine overheating (225 to 230 degrees).

Work was performed to close off gaps around the radiator that were thought to be contributing to recirculation of engine-heated air back through the radiator. Thought (hoped) this would solve the CEL issues but during our passage through the Alleghenies on I-80, the overheating issue has reoccurred.

The coach has been weighed and we are 3,300 pounds under the GVWR and 13,800 pounds under the GCWR. Weight does not seem to be the issue and we are not screaming up the grades.

Not seeing postings about overheating issues within the forum. Are others suffering in silence??

[smlranger]

Did they check engine thermostat/s? If sticking, you can overheat.

There are some folks that believe the big rubber flap with manufacturer's logo hanging at the rear of the coach causes some back flow and prevents good air flowing thru the engine compartment. Not sure I believe it but something to consider.

Are you manually downshifting on steep grades to keep the engine rpm's in the optimal range for your engine? If you allow the engine to lug up grades and just pour more throttle to it at low rpm's, a diesel will run hot.

Is your fan operating properly? On most Cummins applications, the engine ECM sends info related to temps, etc. to a fan controller that lets fan spin faster or slower depending on conditions.

[dusty56]

Originally Posted by P&GD

We purchased our Cornerstone in February. In April we took the coach on a "shakedown" out to New Mexico through the southern U.S. We encountered our first Check Engine Light (CEL) in Texas, where we had the cooling system checked out -- no apparent issues. Since then, we've been experiencing recurring CEL's related to engine overheating (225 to 230 degrees).

Work was performed to close off gaps around the radiator that were thought to be contributing to recirculation of engine-heated air back through the radiator. Thought (hoped) this would solve the CEL issues but during our passage through the Alleghenies on I-80, the overheating issue has reoccurred.

The coach has been weighed and we are 3,300 pounds under the GVWR and 13,800 pounds under the GCWR. Weight does not seem to be the issue and we are not screaming up the grades.

Not seeing postings about overheating issues within the forum. Are others suffering in silence??

thermostat sticking or the fan clutch possibly. I am sure you have plenty of coolant. Unless you see coolant on your toad windshield. Sometimes it runs hotter if you have a motorcycle lift in the rear. That bigger motor needs more open area than the others. I don't know your situation.

I know you don't have to with the 600HP but when you are going up mountains at 60mph and only tacking 14- 1500 RPM's you might want to try what the other thread said downshift manually to get the engine rev.

Also if you have the A/C on turn it off. use the overhead A/C's with the generator.

I travel with a fellow cornerstone owner, I have been all over the rockies this summer never got above 208. Same for the other cornerstone owner.

[P&GD]

Thermostat and fan operation have been checked. Everything comes on when it is suppose to. Belt tension and slippage were also checked. Technicians have stated that the engine and cooling system appear to be running nominally.

When encountering grades, I downshift to maintain 1500 RPM's. I had heard this keeps the engine from lugging but too high RPM's are just as bad as lower. Cummins Customer Service agrees with this approach.

We have a motorcycle lift installed although the initial CEL was encountered pre-lift. Could be a factor although the techs I've discussed the issue don't believe it should be a significant one. Same for the toad.

Have been traveling with the dash A/C on. Will leave it off to see if it helps with the overheating. Wouldn't think that it would drive the engine temp from 208 to 230 but at this stage, I'll try anything.

[Saltydog44]

Man - that's a real bummer Rik. I sure hope you can find the issue soon. Seems like Cummins would be able to find it with a lot less hassle than you've been through. Have you been to a Cummins shop?

You and Melinda sure have our sympathy.

[Steve Ownby]

Originally Posted by P&GD

Thermostat and fan operation have been checked. Everything comes on when it is suppose to. Belt tension and slippage were also checked. Technicians have stated that the engine and cooling system appear to be running nominally.

When encountering grades, I downshift to maintain 1500 RPM's. I had heard this keeps the engine from lugging but too high RPM's are just as bad as lower. Cummins Customer Service agrees with this approach.

We have a motorcycle lift installed although the initial CEL was encountered pre-lift. Could be a factor although the techs I've discussed the issue don't believe it should be a significant one. Same for the toad.

Have been traveling with the dash A/C on. Will leave it off to see if it helps with the overheating. Wouldn't think that it would drive the engine temp from 208 to 230 but at this stage, I'll try anything.

If your overheating issues are occurring when climbing as I expect they are, then I believe your 1500 rpm target engine speed is too low. When on a long climb, where you are having overheating, get your rpm up to 1800 to 1900. Your ISX is governed to 2100 and I believe your rated hp occurs at about 1800. If the temp continues to climb at the higher rpm then back out of the throttle and downshift again. That turbo is a heat producer and if you get your boost pressure down the temp will come down.

[P&GD]

Thanks, Steve. Agree with your thought about the 600 hp rated out at 1800 RPM. I'll kick up the RPM's next time out and see what happens. I'll also keep an eye on the turbo temperature and see if there is a correlation. Can't help but wonder how other owners of these engines can avoid overheating in more challenging situations without doing much more than keeping track of the engine temperature.

[dfunde01]

With the ISX on the K3 you need to get Spartan involved. They design and install the side radiator, cooling fan, and other critical cooling system components as well as installing the engine in the chassis. They also own any problems with the DEF system.

Dave

[GreaTOne65]

Rik, the after all you have done, so far, my first impression, was the temperature sensor was/is the culprit. I have a '65 GTO, that I restored, and was having a problem with the gauge showing it was overheating. After doing everything possible, it was discovered the sensor was for a light, not a gauge, changed sensor, problem solved. My other observation, on my Discovery, shifting down, and standing on the accelerator, cools the engine very quickly on long pulls up hill, more RPMS, doesn't really create more heat, it just recirculates the coolant faster, and will cool the engine better.

[P&GD]

Thanks, Dave.

Spartan is involved. Had the coach in Charlotte for the RV Owner Training earlier this month. They ran the tests that I referred to in the OP and concluded that the engine and cooling system were functioning within operational parameters. It was their belief that the issue was attributed to gaps around the radiator. Parts were requisitioned from Entegra to close the gaps.

[Coma]

Originally Posted by P&GD

Thanks, Steve. Agree with your thought about the 600 hp rated out at 1800 RPM. I'll kick up the RPM's next time out and see what happens. I'll also keep an eye on the turbo temperature and see if there is a correlation. Can't help but wonder how other owners of these engines can avoid overheating in more challenging situations without doing much more than keeping track of the engine temperature.

The engine and transmission computers will not manage your temps. They will only do something if a limits is exceeded. Keep your rpm's near HP peak and monitor temps, if they climb you need to select a lower gear. Do you have a Silverleaf system? You can monitor Manifold temps with it.

What altitude does this occur? If this happens below 5k ft I would suspect mechanical/sensor problem. If it occurs above 5k ft I would suspect a driving technique.

[P&GD]

Thanks, Jim.

Our Cornerstone is equipped with the Trip Tek system, where I'm able to more accurately monitor the engine and transmission temperatures, oil pressure and turbo pressure.

The overheat issues are occurring below and above 5K in altitude. Based upon other comments, I'm beginning to suspect a sensor issue as well. Is there a way to test a sensor?

[Steve Ownby]

Originally Posted by P&GD

Thanks, Jim.

Our Cornerstone is equipped with the Trip Tek system, where I'm able to more accurately monitor the engine and transmission temperatures, oil pressure and turbo pressure.

The overheat issues are occurring below and above 5K in altitude. Based upon other comments, I'm beginning to suspect a sensor issue as well. Is there a way to test a sensor?

Before you get too "wrapped around the axle" about this issue, I would do the following:
1. Next trip out, actively manage your heat/rpm/ turbo boost range. When your temp starts flirting with 200 then get your rpms up over 1800. If they continue to rise then down shift again & back out of the throttle a bit. Watch the turbo boost & try to get it down into the low 20s.
2. If your are still concerned that there is a drivetrain issue after the above, then make an appointment with a Spartan location that has a chassis Dyno and have them run it under load to simulate your conditions & see what issues pop up.

That ISX is a big heavy piece of cast iron and takes a lot of cooling. I suspect that the cooling package may be at the low end of the Cummins spec for that engine but the chassis/coach builders are running out of physical space to add more cooling.

[Cat320]

Originally Posted by P&GD

The overheat issues are occurring below and above 5K in altitude.

Altitude should not make any difference on any of these coaches.