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Old 12-31-2019, 08:20 PM   #1
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Cummins max temp.

I have a Cummins ISC 8.3 engine and I am wondering what the max engine temp is before damage is done. I am also trying to figure out what RPM is the sweet spot for pulling hills with this engine. I have tried 1500-2000 but can’t find the best for climbing hills.
Thanks!
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Old 12-31-2019, 08:32 PM   #2
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I have a 2008 8.3 ISC and I believe the sweet spot is 1800 rpm. My temp is anywhere from 180 to 220 degrees.
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Old 12-31-2019, 08:57 PM   #3
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I emailed Cummins customer care with this question, the first reply stated they required my engine serial #, I sent it to them. This was the reply:(180-212 is normal range) (that SR number was my case number)

" RE: email response \ SR#: 1-103373773861
TSRTechnicalSupport@cummins.com
Mon 5/6/2019 7:51 AM


Ray,


According to the curves and data sheet the engine should not go past 212 degrees. If it is getting 220 degrees you need to bring it into a shop so they can check it out. Have a great day.
Brent
Cummins Care Representative
SR#: 1-103373773861
If you have additional questions please feel free to respond to our support staff by e-mailing care@cummins.com or by calling 1-800-CUMMINS (1-800-286-6467) within the U.S. Additional calling options for outside the U.S. are provided on our website. When contacting us, please refer to the SR (1-103373773861) number listed above, if applicable.
Visit us at www.cummins.com or www.cumminsengines.com
-------Original Message-------
From: fowlerr@hotmail.com
To: TSRTechnicalSupport@<font color="bla...ins</font>.com
Cc:
Subject: Re: email response \ SR#: 1-103373773861


External Sender
re: my ISC engine is in a 40' motorhome; the CPL is 2695, serial # 45902455. I tow a 2013 Chevrolet Silverado K1500, that weighs close to 5,600lbs. The coolant temperature will reach 220° pulling long mountain grades on hot days, but returns to just below 200° after cresting the mountain. Is there a maximum time for the engine to stay at 220°
I was told it will harm a diesel engine to reach 220°, thought I should ask the experts who build the engines.


From: TSRTechnicalSupport@<font color="bla...ins</font>.com <TSRTechnicalSupport@cummins.com>
Sent: Friday, May 3, 2019 8:40 AM
To: fowlerr@hotmail.com
Subject: RE: email response \ SR#: 1-103373773861


Ray,


Thank you for contacting Cummins. I will need the engine serial number in order to look up the specific information on your engine. 220 degrees may be getting to hot but I will need to look that up to be sure.

Brent
Cummins Care Representative
SR#: 1-103373773861
If you have additional questions please feel free to respond to our support staff by e-mailing care@cummins.com or by calling 1-800-CUMMINS (1-800-286-6467) within the U.S. Additional calling options for outside the U.S. are provided on our website. When contacting us, please refer to the SR (1-103373773861) number listed above, if applicable.
Visit us at www.cummins.com or www.cumminsengines.com
-------Original Message-------
From: fowlerr@hotmail.com
To: care@cummins.com
Cc:
Subject: engine maximum safe operating temperature

External Sender
Brent previously replied with the normal operating temperature. Now I have a followup question. What is the maximum safe operating temperature? Will 220°F cause problems on long uphill climbs for Cummins OTR engines, if I stop at the top of the grade and allow the engine to idle until normal temperature is reached?


[THREAD ID: 1-1BHL357C]



[THREAD ID: 1-1BHSTCDH]






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Old 01-01-2020, 04:35 PM   #4
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Accumulator Based HP fuel systems should be in the 180 to 190 range - Common rail will be about 10 to 12 hotter. They really should not be allowed exceed water boiling temp (even accounting for pressure in the coolant system). Diesels run best when coolant temps are below 212..

As far as best rpm, it comes down to what load you got and what terrain you are traversing. IF you can keep it in 6th at 62 and about 1550-1580 rpm it should climb most hills without dropping out of 6th. My ISC normally does but I dont have a toad. The more you have to rpm it to keep the momentum up, the more you will take a hit on fuel but it should still climb fine. A 350ISC with a 4K load will likely drop down to 5th somewhat often going up thru the midwest. But 5th is only 15 <i>(fixed)</I> percent lower than 6th for an alison 3000 so it should not matter much

My gets 8.5 to 9 on level ground with no toad at 62 at 1570 rpm.
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Old 01-01-2020, 05:23 PM   #5
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Ken,

Your cooling fan should kick on right at 212° and lower your cooling temperatures back down to approximately 180ish.

If your coach is routinely exceeding the 212° mark, irregardless of the terrain, the cooling fan is not functioning properly.

A small notebook and a number of the optional software applications work great in monitoring your engine performance.
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Old 01-01-2020, 07:08 PM   #6
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....or perhaps the radiator/charge air cooler are dirty/restricted.

Seems like most of the threads here related to overheat involved cleaning radiator.

A visual ain't gonna get it either. There's hydraulic oil coolers, the charge air cooler then the radiator..very hard to really see the area.
Not a terrible job to remove the CAC and really, really wash radiator out.
(I take it yours is a side radiator)

I washed mine, went from Florida to Montana and never exceeded 210/215 fully loaded in July with toad.
That's reading from my scan tool, not dash gauge.
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Old 01-01-2020, 07:51 PM   #7
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my 07 build isc

i hear fan come on around 210, and it climbs to 212 and that runs it back down in the 180 range and then the slow climb back to 212


i have seen it as high as 218 in summer in hot south texas
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Old 01-01-2020, 09:03 PM   #8
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on my trip home from AZ in the new ISL motorhome i watched the temp from the scan gauge and dash. The temp would be in the 180-185 range during long pulls it would start an slow rise often getting in the 200 range. The after a while it would read 208 at this point i could not hear what happened but it would stay the for a few seconds the a rapid decline to 180 range again.

It pretty much was consistent on this sometimes hours before it would exceed the 207 range and do the same.
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Old 01-02-2020, 07:22 PM   #9
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Strange answer. On a Freightliner Chassis, it is common for the engine to derate when reaching a specific temperature and continue to derate with hitting the Shut-Down temperature. Which for m y FL with Cummins 425hp ISX is 226.

The Engine computer will protect the engine for temperature. The Transmission ECU and Engine ECU will do it best to protect for an Overspeed condition.
However, if you reach a specific RPM, the engine will shut-down and cannot be restarted, until it has been inspected.

Temperature and speed are the killers for diesel.
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Old 01-05-2020, 05:15 AM   #10
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Engine Temperature Notes

What you really need to know and keep in mind are these things:


Assuming these numbers are right...


* Your thermostat will open at 180F

* Water boils at 212F

* Coolant (in spec) can withstand 240F

* Keep your RPMs at the peak torque curve for your engine; and don't lug the engine up a hill.

* Your engine has a coolant filter that needs changing every 50,000 miles. (I think?)

* You need to know what type of coolant you use and if you need to add a coolant stabilizer every year.

My coach uses OAT coolant that is supposed to be for the life of the engine, but most people feel 300,000 miles is it's limit.

* Coolant age is not a factor. But tanking coolant samples is a good idea due to contamination or the mixing of different brands of coolant over the years.

* Occasionally, I would test the coolant ph with a strip.

This summer, my Winnebago-Itasca "Horizon" 40AD, Freightliner, with an ISC-350, and a 3200 lb tow car, started to run 215F while climbing a 5% grade in 105F outside temperature.

I have a side radiator, which is supposed to help keep temperatures down. So I just took it easy up the hill, and on the down slope my temperature returned to normal.

If you temperatures are higher than 190 in normal driving, on a 80F+ day, then you need to make sure your fan is working right... and you Monaco owners need to look into a "Wax Valve"... or something like that. I mention this, because I have read about this upgrade in other posts, but I'm not sure I'm explaining it right.

Anyway, your engine coolant and your engine temperature is something you need to understand beyond making sure you have enough coolant in you engine.


If you are climbing a grade and your engine starts getting up in the 215F-220F range, then I would find a lower gear, go slower, and make sure your engine is at 1800RPM-1850RPM. Then you should see your engine temp drop a bit, which is a good sign!


And on the flats, I think if your engine is running over 190F then you might look into several possibilities:


* Clean the fins on your radiator, charge cooler, and AC condenser.
* Possibly your engine thermostat is stuck partially open
* Maybe your coolant needs changing? ...which is real concern for other reasons than just running hot. As a minimum you need to do a ph-test ASAP!
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Old 01-07-2020, 06:34 PM   #11
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I want to thank all of you for your expertise info. If I lived in the flat land I wouldn’t worry about it as much, but in the northwest we have mountains to climb. I honestly would like to have more torque, but I guess you shouldn’t be in a hurry when on vacation.
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Old 10-25-2020, 12:34 PM   #12
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On my 2000 American Eagle, (350 HP ISC, Cummins 3.8 3/L Chassis: Spartan Mountain Master GT Rail
) we literally just came from Virginia to Arizona. Outside temperatures played a lot into the engine temps.

All the way to Texas, we rarely got above 185-190 even on long hills at full speed (70-80 MPH)

Once we started in to New Mexico and Arizona, it warmed into the 90's outside, we would see a steady 200-210 on the long hills (and from Las Cruces all the way to the Dragoon mountains in AZ it is basically all uphill).

Just had the radiator cleaned, etc, new coolant before we left. For an older RV, I don't think this is too abnormal.

Still, have your local service center advise what you should be seeing. Mine, according to the techs, is well-within norms. I was advised 220 is not even abnormal for the long climbs, but again, just slow down a bit up hills and it will return to normal unless you have a bad fan or a dirty radiator.
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Old 10-25-2020, 02:59 PM   #13
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210 ° is a safe temp. Seems normal to me.
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Old 10-25-2020, 05:40 PM   #14
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All normal temperature for are 330 Cummins .Probably has a 180 or 190. Thermostat .
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