I have a Monaco 40 ft diesel pusher with a Cummins ISL 400hp Turbo Diesel Engine. The temp guage range is 100 to 250 degrees. At 55 to 65 road speed on relatively flat terrain (South Alabama/North Florida) the temperature tends to run around 240 degrees. Is this normal?Thanks for the response. Just to add. My temp gauge and the monitor both show the same temp within a couple degrees. If the sending unit was bad would I still see the same information from both sources?

165-185 is normal, upper end when climbing grades, at least this is my experience. You have a problem with the gauge circuit or an actual problem with overheating.

Runaway Train wrote:I have a Monaco 40 ft diesel pusher with a Cummins ISL 400hp Turbo Diesel Engine. The temp guage range is 100 to 250 degrees. At 55 to 65 road speed on relatively flat terrain (South Alabama/North Florida) the temperature tends to run around 240 degrees. Is this normal?Here's a link to others with the same issue, although most are not experiencing as high a temp. as you, and most have the issue only while climbing grades.

I would suspect that if your diesel motor was actually running that hot it would have broken down or seized up by now. Try a new sending unit, check the wiring harness for the sending unit if you have the schematics. If you are well heeled financially then take it to a dealer - just don't forget the Vaseline jar!Cheers and Merry Christmas!Mike and Carol

Have you ever cleaned the radiator? The outside of the radiator/fins.

Engine Operating Temperature | Good Sam Community

10 Replies

Executive45
Explorer III
Dec 24, 2013
I just came over the Grapevine and my engine temp stayed at 180 degrees....tranny temp @ 184...BTW..that's 6 miles @ 6% grade.....Dennis
dons2346
Explorer
Dec 24, 2013
At that high of temp is correct, I would think you would get an engine warning light and eventually the motor would go into derate mode.
Old-Biscuit
Explorer III
Dec 24, 2013
Runaway Train wrote:
I have a Monaco 40 ft diesel pusher with a Cummins ISL 400hp Turbo Diesel Engine. The temp guage range is 100 to 250 degrees. At 55 to 65 road speed on relatively flat terrain (South Alabama/North Florida) the temperature tends to run around 240 degrees. Is this normal?

Thanks for the response. Just to add. My temp gauge and the monitor both show the same temp within a couple degrees. If the sending unit was bad would I still see the same information from both sources?

What does the temp do under different conditions......climbing hills, slow speed at a crawl, stop and go traffic?
ScottG
Nomad
Dec 24, 2013
I wouldn't drive it any more at those temps. Something is very wrong - but probably just a dirty radiator.
mmccwill
Explorer
Dec 23, 2013
I have the same engine & it should run from 180 to 190 average outside temp & terrain -- Your thermostat would be the first thing to check -- Could be hanging -- It`s a easy fix if you have a side radiator coach -- The dash gauge & monitor gets readings from different sources -- William Willard
Tom_N
Explorer
Dec 23, 2013
Have you ever cleaned the radiator? The outside of the radiator/fins.
Mike_LeClair
Explorer
Dec 23, 2013
I would suspect that if your diesel motor was actually running that hot it would have broken down or seized up by now. Try a new sending unit, check the wiring harness for the sending unit if you have the schematics. If you are well heeled financially then take it to a dealer - just don't forget the Vaseline jar!

Cheers and Merry Christmas!

Mike and Carol
Mich_F
Explorer
Dec 23, 2013
Runaway Train wrote:
I have a Monaco 40 ft diesel pusher with a Cummins ISL 400hp Turbo Diesel Engine. The temp guage range is 100 to 250 degrees. At 55 to 65 road speed on relatively flat terrain (South Alabama/North Florida) the temperature tends to run around 240 degrees. Is this normal?

Here's a link to others with the same issue, although most are not experiencing as high a temp. as you, and most have the issue only while climbing grades.
jtfcons
Explorer
Dec 23, 2013
165-185 is normal, upper end when climbing grades, at least this is my experience. You have a problem with the gauge circuit or an actual problem with overheating.
yrusoslo
Explorer
Dec 23, 2013
no

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Engine Operating Temperature

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