Overheating when climbing hills

You may have issues that still need to be fixed, but I will add one thing. It's important to downshift and bring the rpm's up as many mentioned, but often many then try to maintain the speed they were at before they downshifted, by increasing throttle. This can cause heating issues too.

Example, you are driving 55mph up a grade and start to get hot. You downshift from 6th to 5th or 4th to 3rd (depending on your transmission), but still try to maintain 55 mph by giving it a little more throttle. If the coach is still getting hot, lower your speed to 45 mph, and if necessary, drop another gear to maintain that speed. Now you're not pouring fuel in that causes it to heat up.

Your coach has a small diesel that will not be a rocket up hills and you need to adjust speed for that. Your coach is probably a 35-45 mph coach on large hills.

210 is not overheating, it is pretty much normal for running close to full power, which you car doing on hills. I would be concerned about a rise to 230 F or above.

Climbing is not the same as cruising. Your cooling system has to restrict itself to bring temperature up to 180 F, which is likely the lowest temperature for efficient operation of your engine.

While going up a long or steep incline as you see the temp gauge going up start shifting the transmission manually down a gear and you may have to go down two. Don't strain the engine. Get the RPM's up to red line. Get more air going thru the radiator. My bet is that this will take care of it. Do this first before you spend any money. That is not a strong engine you are climbing with. With my CAT 300 HP in Colorado I have to do this frequently and it will not hurt the engine. (13 years and 121000 miles)

Repeating myself here but a new thermostat is $50 and easy to change. It is paramount to use the serial number and get a Cummins dealer to supply it. Not something off the shelf at your local parts store. My new one looks nothing like the old one.

AZCowboy wrote:
They claimed it wasn't downshifting properly.

What transmission do you have-- Allison 4 speed hydraulic transmission or Allison 6 speed electronic transmission?

And when he claimed it was not downshifting properly, what was the engine RPM at WOT before it downshifted. It should never be below your peak torque RPM. And, yes, manually selecting a lower gear will lower temperatures, particularly if you back out of the throttle a little. Both water pump and fan are turning faster for virtually the same heat load.

Cleaner

I used this stuff on the roof AC coils. Incredible. Spray on and the grime runs off.

I was so impressed I used the remainder on the engine radiator. Again with the little that was left the stuff totally amazed me.

Back to Home Depot to buy ten cans. Great stuff seems to disappear too often.

Using most of one can the CAC and Radiator looked brand new in about ten minutes.

Raise the front jacks and lower the rears so it flows toward the engine. Rinse with low pressure so it forces it toward the fan.

Then I used the rest of that can on the dash air conditioner coil and it too looks like new.

It smells good too.

Reply to joraz - Thanks for those phone numbers. I will give RWC a call. I'm going to pass on WW Williams. I took the motorhome into them with this problem. Their resolution was for me to replace the transmission with a rebuilt transmission. They claimed it wasn't downshifting properly. Not feeling comfortable with that answer (and also not wanting to part with the $6k they were asking to get the job done), I checked with a transmission mechanic I've used in the past. He agreed, if it is upshifting and downshifting on stops and starts, it is probably fine. In addition, another mechanic suggest I manually downshift it to see if it still overheated...which it did. Consequently we decided the problem wasn't the transmission.

Thanks also for the suggestion of using Simple Green. I'm going to look into it and see if it might be something I can tackle by myself.

To all of you that have responded. Thanks much for taking the time. If these suggestions don't work...I'll be back for more advice. :)

ScottG wrote:
By 240 the fan should have been engaged. They make quite a roar so if you don't hear it then that's probably the issue. If it's the clutch type make sure you get genuine a Cummins part. There are much cheaper alternatives but they just don't work right.

A fan clutch has been mentioned by several. I would be quite surprised if this chassis even has a fan clutch. Suspect (strongly) that the fan is BOLTED to the pulley-- no clutch at all.

Easy to tell. When looking at the CAC, suspect you will see bolts securing the fan directly to the pulley.

joraz wrote:

steam it off. I live in Tucson, not sure if any of the locals do that here or not, but will call around. BT

Check with RWC International. Phone is (520) 622-6767. They are on Flowing Wells just south of Miracle Mile. Can also check with WW Williams. They are just across the street from RWC. Phone is (520) 624-8377.

On our rear radiator Cummins 5.9, I followed wolfe's advice re cleaning the CAC and radiator. I used Simple Green which is a great product with an odor bordering on awful. If yours is a rear radiator you will find this job a real pain. You just have to get as much of the cleaner on the CAC and radiator as you can and wash it off as well as you can. I used a garden hose and one of those squeeze handle nozzles. When you get done you'll be wet, maybe greasy and feel great! Good luck.
jor

Simple Green works very well but make sure that you use the Simple Green Extreme, and not the standard Simple Green. The SG Extreme is made to use on aluminum and on aircraft and will not cause problems if not 100% rinsed off. The standard Simple Green may get into the cracks and crevices and, if not removed completely, will cause corrosion in the aluminum fins. Also if standard Simple Green is used, they recommend, in addition to a very thorough rinse, that you use some type of additional protectant to prevent oxidation of the aluminum.

steam it off. I live in Tucson, not sure if any of the locals do that here or not, but will call around. BT

Check with RWC International. Phone is (520) 622-6767. They are on Flowing Wells just south of Miracle Mile. Can also check with WW Williams. They are just across the street from RWC. Phone is (520) 624-8377.

On our rear radiator Cummins 5.9, I followed wolfe's advice re cleaning the CAC and radiator. I used Simple Green which is a great product with an odor bordering on awful. If yours is a rear radiator you will find this job a real pain. You just have to get as much of the cleaner on the CAC and radiator as you can and wash it off as well as you can. I used a garden hose and one of those squeeze handle nozzles. When you get done you'll be wet, maybe greasy and feel great! Good luck.
jor