Community Forums

hewebb · 07-11-2019, 05:44 AM

I searched the forum for this and came up blank. I am sure there are post out there.

Yesterday we were climbing over the Continental Divide west bound on I90 in Montana. Just before we reached the apex the engine overheated and I pulled over and let the engine idle and it cooled off quickly allowing us to finish the trip. I checked the coolant level and it was OK.

I am not sure how to check the fans on the radiator. We will be traveling to Glacier Park today.

Any Thoughts?

GaryKD · 07-11-2019, 06:03 AM

Hi hewebb,
Cooling system maintenance is, most likely, all you need. Consider:
1. Complete coolant change.
2. New thermostat.
3. Radiator flush.
4. Radiator cleaned (exterior). This requires removal.

For me, if the only time this happens is climbing the Rocky Mountains I'd do all but #4 (expensive). It all depends on how the coach will be used.

ptw · 07-11-2019, 06:25 AM

Here is a method of cleaning the exterior of the radiator from Camp Freightliner.

RADIATOR CLEAN OUT METHODS BY FCCC
Dear Campers it has come to the attention of FCCC that the cleaning method suggested of the Radiators and Charge air cleaners are being questioned because of the radiators being made of ALUMINUM and PLASTIC and the cleaning product suggested. (Simple Green).
This product Simple Green is a effective cleaner and it is also biodegradable and when the Directions are followed limiting the contact time and rinsing well, Simple Green will not discolor or oxidize aluminum and is non corrosive, this product has been used for many years to clean aluminum, with no ill effects, it does not provide corrosion protection.
In military testing the product did cause discoloration and some oxidation when allowed to soak for many hours. It should also be noted that the mixture given is 3 parts hot water and 1 part simple green. Put this mixture in portable one gallon bug sprayer and apply to the outside of the radiator and to the outside of the charge air cooler and rinse thoroughly, repeat this process till rinse water becomes clear.
We have contacted the makers of simple green, Sunshine Makers, Inc about this and they have responded to FCCC with this information below:
Because of the possibility of misuse or improper rinsing we have developed another product that has been tested on metals, alloys, plastic, rubber, etc. This is the best retail product that we offer for cleaning aluminum. The product is called Simple Green Pro HD. It is readily available at Home Depot. This product formulation is based on the same formula as our Extreme Simple Green Aircraft & Precision Cleaner and is actually faster acting, more aggressive and also provides corrosion protection during the cleaning process. The dilution ratio will be the same that you are currently using, and it does require a rinse, but it is much safer for aluminum. This product is also safe for plastic, rubber, painted and gel coated surfaces, carbon fiber, and will not discolor anodized aluminum.
They recommend the use of Simple Green Pro HD, you will be able to recognize it by the purple color and Label at Home Depot.
Still use the portable bug sprayer and keep the solution mixture the same, 3 parts hot water and 1 part Simple Green Pro HD. spray on the outside of the radiator and spray on the outside of the charge air cooler and rinse thoroughly repeat as necessary till clear water comes out. Hope this will help settle the debate on Simple Green usage on Radiators and charge air coolers.

tom chelbana · 07-11-2019, 07:07 AM

It is important to keep engine RPM when pull step grades. The engine RPM should be above 1800 to keep engine fan and water pump movement. As mentioned above clean the radiator could be a big part of your over heating issue,
Newmar Man

Runaway4002 · 07-11-2019, 12:30 PM

We had same problem over the continental divide in Colorado in our almost new Ventana. We were using cruise control and the RPM's were dropping and we got hot. No issues with the radiator, coolant or fan per Freightliner when we took it in. They stated it was due to RPM's too low. I posted on this forum and checked with Newmar. The consensus was once again RPM's too low. A similar trip without the cruise control set and keeping up the RPM's has eliminated the problem. Before you spend a lot of money on other potential fixes, try keeping the RPM's up and see if that fixes your problem, it did for me. All that said, if you have any deferred maintenance with your cooling system, I would get it taken care of.

TJ · 07-11-2019, 01:15 PM

We have traveled that stretch of I-90 through the Rockies numerous times and some of the grades are long and steep. As has been noted, it is important to keep the engine RPMs up in order to get proper cooling.

The fact that the engine "cooled off quickly" once you pulled over would indicate to me that you have good coolant flow. And, since coolant level was as it should be, I'd focus on air flow through the radiator. Check to see if you have some debris (leaves, grass, etc.) blocking it.

You don't say what, if anything, you were towing and that could make a difference on those long, steep grades.

If this is the only time you have experienced overheating, I wouldn't be terribly concerned. Check the simple things (coolant level, radiator blockage, etc.), keep the engine RPMs up on steep grades, and let it go at that...unless, of course, you experience more overheating.

TJ

tomgrigsby · 07-11-2019, 05:58 PM

Our 2000 DSDP 3851 heated up to redline going up Sandston mt. in WV. I slowed down to 45 and increased RPMs, temp came down to 230 so I was able to continue to the top. Once over the top the temp went back down to normal pretty quickly. I intend to try the Simple Green treatment, though visual inspection didn't really show any problem with the radiator cleanliness. Next time I'll get the rpms up early and hopefully all will be well.

fagnaml · 07-11-2019, 06:26 PM

For someone who has not ventured into the Rocky Mountains, what is the suggested minimum RPM to keep the engine cool while climbing I-70 or I-80 or I-90 and how soon should down-shifting happen to keep the RPMs up?

TJ · 07-11-2019, 07:32 PM

Quote:

Originally Posted by fagnaml

For someone who has not ventured into the Rocky Mountains, what is the suggested minimum RPM to keep the engine cool while climbing I-70 or I-80 or I-90 and how soon should down-shifting happen to keep the RPMs up?

I like to stay in the 1700-1800 RPM range on long, steep climbs. You will quickly get a sense of when things start to bog down.

We've found that the Allison 4000 series transmission in our 2018 MADP does a pretty good job when on cruise control, downshifting before the engine starts to bog down. We do watch the RPMs and manually downshift, if needed.

TJ

RiverBurt · 07-11-2019, 07:49 PM

It’s not just RPM, it’s speed. Drop a gear, keep the engine at torque peak, you’ll run cooler. Drop another gear, you’ll run cooler yet - same RPM.

Going slower requires less horsepower. Less horsepower = less heat. Besides your coolant gauge, you’ll see the difference in the turbo boost gauge. If you have a pyrometer (exhaust temp gauge), it will show you why the coolant is no longer overheating.

Given a 6-7% grade, if I go up as fast as I CAN, I WILL overheat. If I drop a gear, I won’t.

A heavily-loaded semi crawling up a grade ain’t necessarily going as fast as it can. It’s going as fast as it can without overheating.

Miramichi · 07-11-2019, 08:47 PM

Having done those routes, you will have no problem with heat.

hewebb · 07-12-2019, 07:03 AM

Thanks All
We are traveling so cleaning the radiator may not be possible,but I will give it a try.
I was turning high RPM's during he climb. I will manage them better from now on.
Howard

lwmcguire · 07-12-2019, 07:17 AM

Don't use the economy mode if using cruise

My temperature climbs towing the F150 but doesn't overheat crossing the passes

As noted by posters I keep the 1800 rpm and usually follow the trucks slowing down a bit

PandS · 07-12-2019, 10:43 AM

Quote:

Originally Posted by RiverBurt

It’s not just RPM, it’s speed. Drop a gear, keep the engine at torque peak, you’ll run cooler. Drop another gear, you’ll run cooler yet - same RPM.

Going slower requires less horsepower. Less horsepower = less heat. Besides your coolant gauge, you’ll see the difference in the turbo boost gauge. If you have a pyrometer (exhaust temp gauge), it will show you why the coolant is no longer overheating.

Given a 6-7% grade, if I go up as fast as I CAN, I WILL overheat. If I drop a gear, I won’t.

A heavily-loaded semi crawling up a grade ain’t necessarily going as fast as it can. It’s going as fast as it can without overheating.

Going up at peak torque will ensure that we WILL overheat in our rig. My L9 Cummins develops peak torque at 1300 RPM. That dog won't fight. I climb long, steep grades in whichever gear I can maintain 1800-1900 RPM. The Torque drops off a bit to 1100 ft/lbs or so, but Horsepower is near peak at around 375.

We are currently in Alaska and have made some pretty steep climbs through the Rockies, reaching the top of the steepest in 3rd gear doing about 40MPH, with temps in the normal operating range. YMMV! -Paul