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Old 07-11-2021, 03:46 PM   #1
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Join Date: Oct 2020
Location: Wisconsin
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2007 Holiday Rambler 40skq - How To Clean Rear Radiator Fins

Recently I posted for another issue and happened to mention that I got a Stop Eng light when going up hill when really hot out. I checked diagnostic code and it was for Coolant Temp. There was recent radiator work done by the previous owner right before I purchased and I found the coolant level to be low. I found it about 1.5 gallons low so I added and again got the light on the next trip when going uphill. A kind person in that thread let me know the radiator does need to have the fins cleaned annually since it is a rear radiator. I'm researching on how to do this and have come up with a bunch of questions. If there is not already a post on how to do this I will make one. Questions:

1. Per the picture below and from what I can tell the CAC is the black section on the bottom and the radiator is on the top. That silver section is about 4 or 5 inches deep and from the engine side I see the same thing. Silver section on top and black section on the bottom.

2. I did find that on the engine side there is a bunch of gunk in there and it really does need to be cleaned. From what I can tell you should spray from the rear towards the engine so you don't try passing all the gunk through the fins. Is that right?

3. How does the water and gunk drain out of the fan housing? I noticed on the bottom it is all sealed up. I saw in a post where a guy drilled like 1/2 inch hold in the bottom of the housing for drainage. Is this recommended? Is there a better way?

4. There seem to be two good cleaning solutions for this procedure that I have found. The super duper Dawn de-greaser and Extreme Simple Green. Does this sound right?

5. Is there a post that already tells me all this and describes the best way to clean this rear radiator and CAC? The engine is a Cummins ISL03 400.

Thanks in advance.
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2007 Holiday Rambler Endeavor - 40skq
40' Diesel Pusher
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Old 07-11-2021, 09:34 PM   #2
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You should post your post/question's on the Monaco owners section of this forum.
I have a 2004 Monaco Knight with 330 hp cummins. My cac is on top and my radiator is on the bottom. I know this because I replaced the radiator last summer.
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Old 07-12-2021, 06:46 AM   #3
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Here's some reading material on radiator cleaning.
2004 38DS04 Travel Supreme
Cummins 8.3 ISC 350HP
Spartan Mountain Master
Ford Ranger Towed
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Old 07-12-2021, 08:20 AM   #4
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Take both engine covers off. Yep, two of them. One is buried beneath the closet bottom rail so you have to take the closet doors off. Not an easy chore the first or second time.

From then on I put screws in differently and shortened the (valence)(molding), part over the doors. It was difficult getting it out around the slides. You cannot notice the 1/4 inch missing when reinstalled. To reinstall I use a few sheet rock screws. The dark heads blend right in.

To find the second smaller hatch cover you need to poke around the carpet in the closet. A sharp awl will find the edges. Just cut along the edges. Once you have the covers off lay a piece of plywood down to lie on. Using a small garden sprayer with simple green or Dawn soap and water soak the fins and let them sit for some time. Rinse and repeat. Do NOT use a pressure washer of course.

If it has never been cleaned from the inside you will need to do this several times.

While you are in there change the filter that lives on top of the engine below the long red cover. Not cheap and often get overlooked.
Myron & Deborah
08 HR Endeavor 40 SKQ
400 Isl, 400 HP/// Now 450 HP
2016 Ford F150 Limited V6 with Ready Brake
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Old 07-12-2021, 08:53 AM   #5
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From the back side I stray down the radiator twice every time I wash the camper. Taking a few minutes to make sure water flows through all the little honey cones. If very dirty I mix up some dawn in a spray bottle and between first and second wash i spray the mixture of soap and water. Its wide open from the rear.

About once a year i spray down the inside of the radiator after doing the outside. I figure doing it after the outside it gets some soke time first. From the front there things in your way. It takes a lot longer to spray it down. Maybe spray the dawn first.
If it was real dirty maybe go back and forth between front and rear side. Because you will be forcing the dirt from one radiator to the other (coolant to inter cooler)

I know I'm getting wet. So I do the inside on a very hot day. Put the rear up on the hwh jacks.
Art & Joyce
Thornville, OH
35' DP Endeavor being pushed by a Kia Soul
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Old 07-12-2021, 03:13 PM   #6
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Two cans of this stuff works fantastic.
Myron & Deborah
08 HR Endeavor 40 SKQ
400 Isl, 400 HP/// Now 450 HP
2016 Ford F150 Limited V6 with Ready Brake
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2007, holiday rambler, radiator, rear

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