Check Engine Light - Running Hot

[Runaway4002]

We have a 2015 Ventana 4002 (Freightliner 400HP ISL) and are fulltime for a little over a year now. I performed my morning maintenance check and the radiator overflow tank was right where it should be and always is. We were driving from Grand Junction, CO on Highway 70 to Capital Reef NP in Utah. It was 93 degrees outside and we had been driving on cruise control at 63 mph for a couple hours and had been steadily gaining altitude. We decided to stop for lunch and a quick check of my gauges 15 minutes before the stop showed everything normal. We spent 20 - 30 minutes in a rest area (engine turned off and generator running both A/C's to keep things cool for us and the dogs) and then headed out. We got back on the highway (cruise control set at 63 mph) and after a mile encountered a very steep grade and we climbed (6% + grade) for about 3 miles (speed dropped to about 55 mph) when there was an alarm/alert and our check engine light went on. I took a quick look at my gauges and noted the temp gauge was just barely in the red zone. It stayed there and the light stayed on until we crested the hill and took the load off the engine. The temp dropped and the light went off. I watched the temp gauge for the rest of the drive (very hot and very steep grades over 8,000 feet) and I got to the edge of the red zone but the check engine light never went on again. About 4 hours after we stopped for the night I opened the radiator and noted it was full and fluid felt normal and the overflow tank was right where it should be. There was no evidence of any fluid loss. I assume this was a onetime situation and I will be watching the temp gauge very carefully when we take off in a few days. My questions to the group.........has anyone else experienced this? Should I have left the engine running during our stop so the engine could have cooled down while we stopped? Any other ideas or things I should be looking at? As always thanks for your input.

[Mac99]

Charge air cooler needs to be cleaned, and perhaps
radiator also.

[BBelanger]

Great question and I'd like to hear the answer. If it were me, I'd be asking Cummins/Freightliner.

[Runaway4002]

Charge air cooler was cleaned (blown out) about 3,000 miles ago as part of 30,000 mile service by Freightliner in Tulsa. Radiator was also checked per the Freightliner service checklist. Not sure what type of radiator cleaning you are recommending? Fluid replacement, blow out or wash out of the coils??? Thanks!

[Rowdy Joe]

keep your rpm up. 1800 to 2100 this will help. it works for me.

[siggyd]

When going up steep long hills , you need to shift down to keep the RPM
at about 2000.
Siggy

[apatz]

Welcome to the desert southwest.

[Spk64]

I agree with downshift and get rpms up. I had similar experiences last week. As water temp started to increase I would downshift and this would bring the temps down some.

[Runaway4002]

Thanks for the RPM suggestions. I generally run at 1700 RPM - 6th gear at 63 mph as a general rule. Going up the grade I was generally in 4th or 5th and I did not pay much attention to the rpm's but did note they had increased to around 1900.

[Rotten-Red]

Originally Posted by Runaway4002

We have a 2015 Ventana 4002 (Freightliner 400HP ISL) and are fulltime for a little over a year now. I performed my morning maintenance check and the radiator overflow tank was right where it should be and always is. We were driving from Grand Junction, CO on Highway 70 to Capital Reef NP in Utah. It was 93 degrees outside and we had been driving on cruise control at 63 mph for a couple hours and had been steadily gaining altitude. We decided to stop for lunch and a quick check of my gauges 15 minutes before the stop showed everything normal. We spent 20 - 30 minutes in a rest area (engine turned off and generator running both A/C's to keep things cool for us and the dogs) and then headed out. We got back on the highway (cruise control set at 63 mph) and after a mile encountered a very steep grade and we climbed (6% + grade) for about 3 miles (speed dropped to about 55 mph) when there was an alarm/alert and our check engine light went on. I took a quick look at my gauges and noted the temp gauge was just barely in the red zone. It stayed there and the light stayed on until we crested the hill and took the load off the engine. The temp dropped and the light went off. I watched the temp gauge for the rest of the drive (very hot and very steep grades over 8,000 feet) and I got to the edge of the red zone but the check engine light never went on again. About 4 hours after we stopped for the night I opened the radiator and noted it was full and fluid felt normal and the overflow tank was right where it should be. There was no evidence of any fluid loss. I assume this was a onetime situation and I will be watching the temp gauge very carefully when we take off in a few days. My questions to the group.........has anyone else experienced this? Should I have left the engine running during our stop so the engine could have cooled down while we stopped? Any other ideas or things I should be looking at? As always thanks for your input.

IMHO this is not abnormal for DP's in high ambient temperatures on steep mountain grades. We may have the power to go faster up the grade but we don't have an adequate cooling system to keep things cool for an extended period of time. In these conditions you have to watch your engine temperature gauge and if necessary drop down a gear and keep rpm's near 2100 to keep radiator fan spinning as fast as possible. Keep dropping gears until you can maintain engine temperature in a safe operating range.

[Rotten-Red]

Originally Posted by apatz

Welcome to the desert southwest.

Yes .

[Dutch Star Don]

Not to offend anyone, but many of those telling you to downshift on the grades are talking about experiences with their older diesel engines and cooling systems. You have a modern coach with a modern cooling system. It shouldn't have gotten hot, even out west. The only reason to downshift on modern coaches is to maintain your speed. Since you're still under the Freightliner warranty, I would have it checked. It may be having a thermostat or engine fan issue.

We've run those grades many times (love that area) in our 2005 Diplomat with a rear radiator towing a full sized pickup with a RZR in the bed, almost 8K. We never got hot running through in 100 degree temps.

Our Dutch Star which has a side radiator (not really a fair comparison) runs through their at 195 - 200 degrees on 100 plus degree days.

[Stealth01]

Runaway,
Welcome to the world of "Rear Radiators"! First, you didn't mention if you had "Mode" selected on your transmission... When ever you're climbing be sure to "Deselect" Mode. When on a long climb, because you have a rear radiator, not a side radiator, you want to down shift to hold your revs ~2,000 to 2,100 RPM. Because you have a rear radiator you want to maximize the airflow through the radiator! You did not mention your engine going into "degrade" mode so I believe your system was operating within normal parameters. The "Amber" check engine light was telling you that your engine was getting warm. You can look up your specific engine parameters up but I think you will find our 500 ISM numbers are pretty close:

• Normal Range: 190F - 205F
• Amber Check Engine: 216F
• Stop Engine (and engine degrade): 226F
• Thermostat Opens: 180F
• Thermostat Fully Opens: 201F

[pilotspike]

Originally Posted by Dutch Star Don

Not to offend anyone, but many of those telling you to downshift on the grades are talking about experiences with their older diesel engines and cooling systems.....

Not to offend Don, but I very much disagree with him

Sounds like you let the RPM drop too much, which just getting out of Camp Freightliner last week, I believe Freightliner would agree. The fans kick on at approximately 211 degrees, and are good for about 15 degrees of temperature reduction. However, the air boxes, etc, are designed to sufficiently cool at a minimum RPM, but I dont believe that RPM is as low as cruising at 65 MPH in overdrive. Also, lugging the engine causes you to put more fuel through it at a lower RPM which will generate more heat. Now, if you were at 2300RPM and it was overheating that would likely require a phone call to freightliner. But if you had mode on and were pulling that hill at 1700 - 1800 RPM, then I would expect it to overheat.

John