Cornerstone Overheating Issues

[Genset]

I have a ISM500 in a 36'. 36,000 lb with toad, running south on I-25 from Rancester, Wy to Denver, had heavy head winds from 12 to 2 o"clock, driving 70-75 in 90+ temps,I finally backed off to 60-65 , dropped to 5th gear, everything was fine except I limit the engine temp to 200f,. Yes most run over that, I do not. When I got back to Va (home)' , I cleaned some dirt from the exterior of radiator and CAC .

[spike45]

Originally Posted by Cat320

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

You could not be more wrong. Altitude affects the cooling system in that the air is less dense thus there is less cooling available. Engines sold into high altitude applications are typically derated from their sea level ratings due to decreased heat transfer in heat exchangers (radiators). The only way around that is to increase the radiator area and fan size.

[Coma]

Altitude hurts you twice. Once in that because of reduced density you get less heat transfer from the same cubic foot, the air has less mass. Twice because the turbo charger has to work harder to make up the difference in MAP, especially as you get when demanding rated HP as in climbing. The added heat from turbo compression then adds to the cooling load.

Although Cummins rates the engines for continuos use at 100% rated power below 10k ft, I can't make myself do that. As Genset mentioned you must manually derate.

I agree with Steve Ownby, as he has a big Cummins also. For example, I use these numbers on my ISC. I got this from an old trucker who used to pull the divide on I-70. Max boost is ~24, max governed RPM is 2200. My normal temp range is 175-195. When my temps go above that I drive 1950-2000 rpm and limit boost to ~20. This is the derate. If I continue to heat, I drop a gear. On high altitude long pulls I end up end 3rd, or 2nd if above 6% grade.
Although you weigh more your ISX will allow you to shift less and climb faster using this technique.

Does the Trip Tek keep ECM faults and does it report the ECM numbers? A comparison between the gauge and what the ECM reports could help you see a sensor fault.

[brrving]

I have the ISX in my Coach and run consistently around 195-200 deg. at all speeds. Climbs hills with no issues. I have not seen more than a couple of degrees increase when climbing. I am suspecting it is in how your cooling system is installed and/or the fan speed.

[Genset]

Chris, when I left Rancester, Wy, headed south, my ISM500 ran up to 200as headed south, wasa hot dry day with eavy headwinds and drivibg 70-75, finally decided to back off to 65-70 and dropped to 5th gear as will not let it o ove 200. Trusy all is normal at home.
Good to see you here.
Dave M

[Cat320]

Originally Posted by spike45

You could not be more wrong. Altitude affects the cooling system in that the air is less dense thus there is less cooling available. Engines sold into high altitude applications are typically derated from their sea level ratings due to decreased heat transfer in heat exchangers (radiators). The only way around that is to increase the radiator area and fan size.

My answer was an over simplification. Of course altitude affects engine temperature due to the thinner air. At higher altitudes the turbocharger compresses the air flowing into the engine. This way, more fuel can be burned, which results in greater power from each explosion within the cylinder and creates more heat. This also provides the advantage of the turbo over a normal reciprocating engine since it maintains more of its power as it climbs.

I recently crossed the Rockies and my engine temp went up seven degrees.

[J Walker]

I did not find a suggestion to clean the radiator. I take it that it is a side discharge radiator that is unlikely to get dirty. Never the less it is easy to clean and it eliminates an item off of the list.

[P&GD]

Thanks to all for your suggestions and comments.

Through the efforts of Spartan Chassis, we took our Cornerstone to a Spartan authorized facility that is also a Cummins service center last week.

After working with the coach for about an hour, the local service manager told me that they initially noticed that the connector between engine fan clutch assembly and engine computer was disconnected. What he couldn't determine is whether this condition has always existed or is simply the result of a previous technician forgetting to reconnected the plug after doing some testing. Once the plug was reconnected, they tested the engine and it was very apparent that the fan came on (I think everyone in the facility could hear it). They did some additional tests and reported back to Spartan. The Spartan customer service manager got on the phone with me to express his satisfaction with the testing and confidence that we have solved the issue. I'm a bit skeptical as three separate technicians (in two states) have looked at the coach and never noticed that connector was not plugged in???

We've taken the coach to the eastern shore of Maryland for the three day Labor Day weekend and will be traveling to North Carolina next week. The trip from central PA to Ocean City was not difficult and the engine temp did not get over 201 degrees. Not high enough to trip the fan. Can't say that was even a test. The bigger challenge will be next week when we transit to western NC. Fingers will be crossed.

Stayed tuned!

[Crippsfl]

I find it unbelievable that that could have been missed. What is the old saying "Start with the simple things and move up" How has it done since your fix??

[P&GD]

Having recently completed a RV Technician course, that is one of the things that was drilled into us: start with the basics and move to the complex. Anyway, since I write the previous post, we have traveled to NC mountains, IN, west to AZ and east to TX. Up and down mountain grades, the engine has performed much better. No engine readings over 215 and when they got that high, it was quickly back down to 200 - 205. No downshifting was required. The ISX performed as other posters indicated -- it is a beast.