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Robert
Robert, RV Mechanic
Category: RV
Satisfied Customers: 12167
Experience:  18 yrs. RV experience including Cummins North West, Country Coach, Monaco Coach - vendor certified.
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I have a 2005 Motorhome with a cummins 400 and I have two

Customer Question

I have a 2005 Motorhome with a cummins 400 and I have two questions
First it overheats is there a thermostat that can help this problem This happen when I climb hills. I downshift to increase RPM but it still happens on long hills
Second would it help to change injectors to increase horsepower to eliminate the overheating
Submitted: 6 months ago.
Category: RV
Expert:  Robert replied 6 months ago.

Hi my name is Robert.....

Yes there is a thermostat on top of the engine block, I was looking for a picture so you have an idea and found a manual that will show the location for you, click HERE and see page 12-49 it will also have some testing. Also I would verify your fan is spinning at the proper speed, or make sure you see a big difference between cold and hot, when the engine is cool the fan should be spinning slow, as you come up to operating temp the fan should be on high speed and you should be able to notice a big difference. A cummins shop can hook up with the software and make sure the fan is coming on when it should and verify the RPM'S...

I am not sure on the second part, if at all that would affect the overheating, sometimes you can calibrate the engine computer to get extra HP but I would advise to have a Cummins shop let you know what options are available for that. I might start with checking the fan speed and then changing th thermostat out and see if that helps at all... Hope this helps some... Robert

Expert:  Robert replied 6 months ago.

Hi I see you have not selected a rating, if you need more help on this please let me know.... Robert