Radiator Cleaning

One reason that side engine radiator Diesel coaches are popular is that it takes all of those radiators at the back of the engine and moves them to the side where they make it far easier to access the engine, and they are out of the line of fire for oil coming off the engine or up from the road. But rear mounted radiators are very common. When mounted back there, they have a habit of getting really grimmy because any oil pushed into the radiator fins by the air flow will then hold any dust or dirt kicked up by the vehicle. In most cases, there are three separate heat exchangers to worry about. Of course, the engine radiator is the one everyone thinks about, but there is also a radiator for the transmission as well as one for the Charge Air Controller (CAC). While the need for cleaning is probably greater for rear radiator systems, both styles can benefit from regularly cleaning out the gunk.

The CAC is used because of the turbo found on most Diesel engines. The turbo takes incoming air and compresses it using exhaust gas to drive the compressor turbine. The result is that the incoming air is heated and heated air is less dense. So the Charge Air Cooler reduces the temperature of the incoming air to increase its density. All of that because the power of the engine is greatly affected by the amount of air it can take in during each cycle. Cooler incoming air equals more power delivered.

This write up is about what I do to keep all three of those clean, and not a recipe for you to do it yourself. If in doubt in any way about this, then please take your vehicle to a maintenance provider and have the radiators cleaned professionally. It involves working around the engine and the use of some chemicals that are caustic but are all normal household or garage cleaners. We accept no liability if you do this and have a problem.

You can hurt yourself, or damage your vehicle if you are not very careful, so be confident in your ability before doing this.

First, I want to give credit to Tom Cherry from a Monaco users group for this process and recipe. I’m not sure if he is the original source of this brew, but Tom published this the first time I saw it.

I’ve used it on a Monaco Knight that had heat problems which had gotten worse with time, and dirt build up. The Knight had a Cummins ISC engine which did well enough going down the road, but I had reached the point of watching the temperature gauge for how fast I could drive up a mountain to keep it from overheating. I had gotten really good at letting off the throttle to slow my ascent based on the engine temperature. I believe, but with out any hard data, that the major problem was actually the CAC and not the engine radiator, mostly because when I cleaned the cooling system the first time, I got far more oily grime residue from the CAC area than from either the engine or transmission sections. Either way, it worked and I was now limited by engine power for my speed up a hill, not the cooling system.

Before we begin, one point that I will emphasize: rinse, rinse, and rinse again. These chemicals are harsh but safe if used as directed but you want to make sure to get any residue off the aluminum parts. Also, when rinsing make sure to use low water pressure. The fins are easily bent but very difficult to get at to straighten.

Be sure to use your PPE (personal protective equipment). In this case, rubber gloves and eye protection. And probably some old cloths that you don’t care about.

Cleaning

Simple Green (YES….it IS SAFE for Aluminum if exposure is limited and it is thoroughly rinsed….look it up on the Simple Green webite). There are also versions of it sold specifically for aluminum cleaning if you prefer.

Dawn Detergent

Black Magic Bleche -Wite. This IS potent stuff….but it is VERY diluted. Used to be Wesley’s

NOTE….if you add common Household Bleach (maybe a quart or so) to this, it is ALSO a fine mold and stain removal…. folks in the south have mold and “black mess” from all the pines…

3 Qt water (hot if you like)

1 Qt of Simple Green…..if this is your FIRST clean….otherwise, a Pint would
probably work as well

½ to one Cup of Black Magic Bleche-Wite (the Tire cleaner – auto parts stores and such and Walmart have it)

¼ cup of Dawn (probably any good dishwashing liquid), but pure DAWN is used in a lot of commercial applications and has a stellar record.

Hose down the radiator with low pressure water. Tom has a side radiator and does the process from the outside. I have had two coaches with rear radiators and do mine from the inside accessing the engine from the interior access hatch. Some have suggested running the engine while spraying because it is difficult to get both the rinse and the cleaning solution all around the radiator system, but I have not done it that way yet and it is clearly more dangerous. I just spray a lot on the areas I can reach and let it run down. After doing the inside, I then continue spraying from the outside where it is easy to coat one side of everything. The pressure from the sprayer helps is penetrate between the fins, just be very careful not to bend them.

Use the above cleaning solution in a pressurized garden sprayer. Spray it Top to Bottom – Vertically and move horizontally …….repeat going from Left to Right (or vice versa). Start at the top and then work your way down. By going BOTH directions, you will get much better coverage and penetration. It’s going to be messy but you may need to crawl under the vehicle to spray from the bottom side as well. I haven’t seen the need to do that yet. Doing it from over the engine means the fan and the whole engine tend to block getting the solution where you want it, so I try to soak it as much as I can and let the excess run down to the parts I can’t reach. Then given it a second coat all over from the back of the coach.

LET IT SIT …… maybe 5 to 15 minutes or so. The Dawn will keep it on and let it work or dissolve the grease and grime.

Use a GARDEN HOSE……not a Pressure Washer….and rinse it. Use the same
technique. Start at the top and go side to side working your way down.
THEN at the top, again, go up and down…..and work your way to the other
side. Rinse with plenty of water, at low pressure, from both the inside and outside.

A LOT of folks will also start the engine and spray from the inside. Tom
doesn’t do that nor do I…..not that it is bad or good, he just doesn’t do it and I have not found it necessary to get it “clean enough” (to not overheat).

What you DO want to do is to RINSE and RINSE until you do NOT see any suds or evidence of soap dripping down…..then RINSE again…..

CAUTION…..do NOT decide to use TOO much of the Bleche-Wite. It is potent. A chemist can tell you that. It will clean your tires. The first time I cleaned the Knight, I got a LOT of stuff out and it made a world of difference in the engine temperature. After that, with an annual cleaning, it has produced much less oily residue coming out.