05 Monaco Cummins 300 running warm to hot

[was_butnotnow]

At times gets a beeping when the Cummins 300 goes above 200 deg. Starts slow and gets louder at the temp goes up. A/C off and pulling Buick Encore on a dolly.
Had been on dusty road so washed the radiator. Seemed to help but later going in I 15 north in Utah starts running on the top edge of running hot. Doesn't stay hot but goes in and out with the load.
Fluid is 1/2 between the lines.
This is a new to me MH so no history.
Any ideas.
Looking for Cummins diesel service places and found one on our way north at Color Country Diesel in Cedar City UT,
Is there something I should try before I hand it off to a service center.
BTW I get no dash warning lights just the low and louder beeping as the temp goes up. Never gets above 225 deg. BTW daytime temp on the road 100 deg. Did the same things yesterday heading north to Kingman AZ in the heat. It does drop down when not under load.
Heading to Idaho as camp hosts for the summer.

[Ivylog]

You need to see if a rubber hose has been added to the crankcase vent tube on the side of your engine that runs behind/past the radiator. If no hose add one so oil does not get sucked up into the radiators making it difficult to clean.

If you can see solid stuff on the radiator, from inside the MH, spray with dawn and using a brush scrub until loosen and wash off downward.

[donkeydew]

jplante4 wrote:
I'm going to try AC coil foaming cleaner this spring. I'm thinking the foam will force the crud out.

The problem with CAC back-to-back with the radiator is that cleaning one pushes dirt into the other. There's really no way to get in between to spray out the middle without removing the rad.

foaming a/c coil cleaner works great i have used it for several years with great success

[wolfe10]

At least LOOK at the front of the CAC (around the perimeter). Yes, from the bedroom or closet.

Tell us what you see.

[jplante4]

I'm going to try AC coil foaming cleaner this spring. I'm thinking the foam will force the crud out.

The problem with CAC back-to-back with the radiator is that cleaning one pushes dirt into the other. There's really no way to get in between to spray out the middle without removing the rad.

[was_butnotnow]

We stopped at Cummins service in Cedar City and they got us in to power spray our radiator. Don't think they sprayed on the front side. It helped but don't think it cured the problem. Did not run as warm but still not what I think it should. Does help to downshift on hills.
When we get to our camp host site in Idaho will get out my power sprayer and go in from the bedroom and see if I can do better.
They only charged us $54 so who can complain.
The said they do this all time on these engines, so we assumed they would do a good job.
Anyway, this is a learning experience. Thanks.

[wolfe10]

OK, if all you see from the back is ONE piece, that is the radiator.

The CAC will then be in front of it. And, that is what needs to be cleaned.

Access the top of the motor from the bedroom or closet. Fan shroud is easy to find. Use a strong flashlight to look at the front of the CAC (inside fan shroud). Verify that the perimeter is as clean as the center (the fan slings the dirt to the perimeter).

Not much fun to get in there and clean it, but certainly nothing requiring special still.

You will need:

garden hose with garden nozzle.

Simple Green EXTREME (Extreme is aluminum-friendly as it was developed for degreasing aluminum aircraft)

Old clothes, as cleaning is NOT a clean job.

Most owners can do as good a job as a dealership-- unless it has been neglected so long that the radiator and CAC will have to be removed and steam cleaned.

Again, the dirt will be on the FRONT of the CAC.

[was_butnotnow]

The radiator is from the back one full piece and that is where we cleaned. Did not know about going under the bed. The Cummins service center is about 60 miles up the road in Cedar City UT. Will stop and see if they can help.
Thanks for the info.
Will keep updating.

[wolfe10]

The questions I asked are very important to keeping your cooling system operating properly.

Did you wash the radiator from the BACK or the FRONT (from the bedroom)?

Is the CAC ABOVE or IN FRONT OF the radiator?

You could also open the back of your coach and take a picture to post here-- it would show if you have "one thing on top of the other" or whether you just see "one piece". If you see only one piece, the "other one-- the CAC) will be IN FRONT OF THE RADIATOR. If that is the configuration you have, it must be cleaned from the front-- the CAC "filters out" the dirt and debris. Cleaning from the back is basically useless.

[jplante4]

OkieGene wrote:
What is CAC ?

Charge Air Cooler. It's an air-to-air radiator that cools the air coming out of the turbo charger before it gets to the engine. In cars and planes, it's called an intercooler. Cooler air is more dense and is more efficient in combustion.

[OkieGene]

What is CAC ?

[was_butnotnow]

DSDP
That makes so much sense. Thanks for taking the time to help out another newbie MH owner.

[DSDP_Don]

On my 05 Diplomat, I would pull the floor up in the bedroom and wash the stacked CAC over radiator with a garden sprayer full of Dawn detergent. I would also use one of those pinching tools from Harbor Freight that you push the button and three pinchers come out to reach debris at the bottom. Monaco's fan shroud is sealed at the bottom. A lot of debris can get down into the base of the shroud and build up. From the bedroom floor, I would carefully reach down with the pinchers and pull out all the debris. Often found a lot of paper and baggies.

Once the debris was gone, I would liberally spray the CAC and radiator from the floor opening. If you can get a garden hose into the bedroom, it's best to spray from there. You can't clean these well enough from the rear engine doors.

Once I did my rinse, I would go to the rear of the coach, open the doors and spray CAC and radiator liberally again. Once done, I would fire up the coach and while laying under one side, spray into the fan blades and allow fan to push everything through the CAC and radiator.

Lastly, Monaco added a funky alarm (not Cummins) that would start to alarm by sounding like a chirping and then get louder to where it finally alarmed. Our brand new Diplomat did this on the way home from the dealer. When the temp started to go up, it would start this very low chirp and increase. We stopped at the base of the Grapevine in California and called Monaco. They told me to disconnect this secondary alarm and forget about it.

I found the alarm under that removable dash panel atop your instrument cluster. Never had another issue.

I know you're on the road and some of the above would be tough, but it is the best way to clean the CAC and radiator.

Finally, if you still have an issue, my next guess would be to look at the thermostat.

[was_butnotnow]

Think it is stacked as it is flat all up and down. Nothing sticking out on top of anything else. Just a huge radiator with an upper and lower unit on top of each other.

[wolfe10]

Tell us how you washed the radiator.

And is a "stacked" cooling system (CAC above radiator) or a "sandwiched" cooling system with the CAC in front of the radiator?

The more details on what you have the more we can help-- Monaco made a number of different DP configurations.