Cleaning The Radiator & CAC

[wolfe10]

Though written for rear radiator, the process is virtually the same for side radiator except the dirt will be on the outside-most thing (inter-cooler or A/C condenser):

On all coaches, but PARTICULARLY REAR RADIATOR coaches, the CAC (Charge Air Cooler, also called inter-cooler or after-cooler by some manufacturers) and radiator need to be cleaned AT LEAST ONCE A YEAR.

You can verify that you actually need to clean them by taking a strong flashlight. Access the engine from the TOP (bedroom). Shine the flashlight inside the fan shroud/between fan blades. The fan blades "sling" the dirt toward the perimeter, so you want to make sure that the perimeter is as clean as the center (You are looking at the front ((Front of coach)) of the CAC. The radiator is behind that the CAC (back of coach). Yes, there are a few coaches with stacked radiator/after-cooler and these can be cleaned from the back (back of coach).

If you just have dirt on the CAC, a hose with garden nozzle will work fine. If there is oil/greasy deposit, get the engine a little warmed up and turn it off. Wet the after-cooler and spray some Simple Green EXTREME (which is aluminum-friendly) along with water on it (CAC) from the FRONT inside the fan shroud. Let sit, but not until it dries out. Hose out. Repeat.

Pressure washers are dangerous -- it is hard to maneuver them around the fan blades and VERY easy to bend the fins.

You will also want to clean the radiator which is done from the back/outside of the coach. But this is NOT where most of the dirt will be deposited.

And make sure the crankcase breather (1" ID open hose on most Caterpillar engines) is extended to behind the air intake (shroud) for the cooling system. Also verify that the extension ONLY goes downhill from the engine (no dip loop or sag) or you could do serious engine damage in cold weather. One of the byproducts of combustion is water vapor which can freeze if allowed to collect in the extension and if it blocked the whole tube BAD NEWS.

Now, if you are climbing a hill and experiencing overheating, use the transmission down arrow to select a lower gear. For a given road speed, XX number of HP are required (read that also as heat produced). Producing XX HP (same heat load) but with the water pump turning at say 2,100 RPM instead of 1,600 RPM WILL reduce engine temperatures. But it will also increase fuel consumption. So I view this as a short range fix ONLY. Best answer is to get the cooling
system back to 100%.

Brett Wolfe

[tbutler]

Brett,

Thanks for the information. Your technical tips are very helpful. I always learn something. With our side radiator I usually hose it out good with a garden variety sprayer every time it gets a good wash. I hadn't used any detergent and that would be a good idea once in a while.

[pete@waterworksconstruction.net]

Hi All - One reason for the frequent overheat issues with diesel pushers is the engine crank case breather tube constantly puts out an oily smoke that is in front of the radiators (engine, turbo aftercooler, dash and coach a/c, transmission) -- so the oil coats the radiators as we drive down the road. Then the dirt and dust in the air sticks to the oil and the radiators foul in short order -- causing overheat problems.

To cure this cause, look under the engine area with the engine running and warmed up. You will see a smoking hose or pipe pointed down. Turn off the engine, safely block the wheels, and let it cool down. Climb under, and add a piece of pipe to the breather tube end with as few fittings as possible, and run it out past the back bumper. Now the oily smoke will be behind the radiators when you drive, so will not be able to coat them with oil. Our breather was a rubber hose, so we just inserted a piece of pipe, and hose clamped it. If yours is a solid tube, you could use a short piece of hose with two hose clamps to make a coupling between the two pipes.

This should greatly extend the time between cleaning, and I would think an air compressor blow out, followed by a garden hose should be about all you will need (that is how we clean large construciton equipment radiators).

If yours is currently oil fouled, you may need to go to a shop and get it cleaned, but do the fix first and you may not need to do it again. It cost over 600 bucks to have Freightliner clean ours, then someone told us how to fix it (in a Wal Mart parking lot -- THANKS BILL!!) Pete

[wolfe10]

Pete,

I totally agree. On all diesel engine built before January 1, 2007, the crankcase vents to atmosphere. You want that moist, oily vapor to exit BEHIND the fan shroud (intake for cooling system). You don't have to run it all the way to the back of the coach to achieve this, but clearly need it extended to behind the fan shroud.

I will repeat the caution I posted in the initial post on this subject:

"And make sure the crankcase breather (1" ID open hose on most Caterpillar engines) is extended to behind the air intake (shroud) for the cooling system. Also verify that the extension ONLY goes downhill from the engine (no dip loop or sag) or you could do serious engine damage in cold weather. One of the byproducts of combustion is water vapor which can freeze if allowed to collect in the extension and if it blocked the whole tube BAD NEWS."

Brett Wolfe

[Walt2137]

This is a procedure I used when we had a 99 Monaco Diplomat with good results.

I tried a new way to clean my radiator A while back and it really got a lot of black gunk out. First let me say that

I have cleaned the radiator 2 to 3 times a year for the past 4 years. I used a 2 gallon garden sprayer the type with the wand and

fill with 1 gal of Simple Green, on the 99 dip I can raise the bed to get to the radiator, I first sprayed with water ( be careful not to

wet down the alternator) then soaked it real good with Simple Green, about a quart. Closed the engine cover, cranked the engine, opened the

engine cover and sprayed about another 2 qts of soap in the fan be careful with the wand dont get it in the fan, I dont think this would

need to be done every time), closed the engine hatch and run the engine up to about 1500 a couple times to get the soap thru the

radiator. I then shut the engine down and let it soak for 30 minutes. Washed the radiator with water restarted the engine and

washed with water some more, close the hatch run the engine up to about 1500, I did this a couple times. Shut the engine down and washed

from the rear. I was surprised at the black gunk that was between the CAC and Radiator. After testing I found that this method dropped my

Trans temp by about 10 deg in city driving and in hilly country on those +90 deg days according to the VMSpc program that I run on my laptop.

I did not use a pressure washer (but I think you could with the gentle nozzle), I used the regular water pressure 50# with my hose and spray nozzle.

Note be sure to rinse good to remove all simple green from the alum CAC and radiator.

Walt N Will

F191141

[wolfe10]

This is a procedure I used when we had a 99 Monaco Diplomat with good results.

I tried a new way to clean my radiator A while back and it really got a lot of black gunk out. First let me say that

I have cleaned the radiator 2 to 3 times a year for the past 4 years. I used a 2 gallon garden sprayer the type with the wand and

fill with 1 gal of Simple Green, on the 99 dip I can raise the bed to get to the radiator, I first sprayed with water ( be careful not to

wet down the alternator) then soaked it real good with Simple Green, about a quart. Closed the engine cover, cranked the engine, opened the

engine cover and sprayed about another 2 qts of soap in the fan be careful with the wand don't get it in the fan, I don't think this would

need to be done every time), closed the engine hatch and run the engine up to about 1500 a couple times to get the soap thru the

radiator. I then shut the engine down and let it soak for 30 minutes. Washed the radiator with water restarted the engine and

washed with water some more, close the hatch run the engine up to about 1500, I did this a couple times. Shut the engine down and washed

from the rear. I was surprised at the black gunk that was between the CAC and Radiator. After testing I found that this method dropped my

Trans temp by about 10 deg in city driving and in hilly country on those +90 deg days according to the VMSpc program that I run on my laptop.

I did not use a pressure washer (but I think you could with the gentle nozzle), I used the regular water pressure 50# with my hose and spray nozzle.

Note be sure to rinse good to remove all simple green from the alum CAC and radiator.

Walt N Will

F191141

Walt,

I like a lot of the way you do it, but am concerned that the wait time, particularly if the CAC and radiator may be warm. This may allow the soap to dry on the metal. I would strongly recommend against doing that.

Now, if you continue to keep it wet, but not with so much water that you rinse out the soap, that is great.

And as you have found, with a SANDWICHED CAC/RADIATOR, you have to clean from the front (where the majority of the dirt is) and the back, since you don't want to use high enough water pressure to clean both from one direction as PSI high enough to go through the radiator, air gap and CAC would result in a high likelihood of bending the fins.

Brett Wolfe

[BMB2311]

When cleaning the radiator I wouldn't use Simple Green. I am an airplane owner and on several airpane forums there are posts that Simple Green is corrosive to aluminum. Most if not all radiators are constructed from aluminum. I understand there is a new Simple Green formulation for aircraft that is not corrosive and I would think it would be safe for radiators as well. From Simple Green's web site:

FAQ

Aircraft Cleaning – Is Simple Green® safe for cleaning aircraft?

Simple Green manufactures products specifically designed for use on aircraft. Products available on the market are Extreme Simple Green® Aircraft & Precision Cleaner and Simple Green® Pro HD. These products were initially developed for the aircraft industry and extensive testing shows that they are safe for use on aluminum, plastics, rubbers and high tech alloys, even in the most extreme circumstances. These products conform to both Boeing D6-17487P spec for general aircraft exterior cleaning and Pratt & Whitney PWA 36604revC spec for aircraft engine cleaning.

2003 Monaco Executive

500 Cummins ISM

[wolfe10]

Yup, Dawn dishwashing detergent works well and is a lot less harsh to the metal.

Brett Wolfe

[johntelling]

Since I recently became a member of FMCA, I am very impressed with the way one can get help and friendly advise. I had an overheating situation with my coach when travelling over the Grapevine to Southern California last summer. This e-mail string convinced me that I may have a plugged radiator, but I was not able to get to it. It turns out that the engine cover (accessible from the bedroom closet) has never been opened, so I am guessing that the radiator has never been looked at. The carpet was tacked down so I had to pry it up to get to the cover. The radiator was filthy - I am amazed that I didn't overheat on level freeways!

Thanks for the great information. With a little Dawn and some water, the radiator looks like new!

JT

[wolfe10]

With many getting ready to hit the road for the summer and it's hot driving conditions, it is time to revisit this subject.

Cleaning the cooling system not only keeps your coach from overheating, but gives more HP and better MPG as the CAC is able to keep intake air temperatures lower.

Brett

[kenosavvy]

I don't see anything in your article that applies to my diesel engine. It's a 2001 Cummins ISB, and the CRC and the radiator are rear mounted and side by side, not sandwiched. I've cleaned it before but not sure if I'm doing it the best way. I get into the engine compartment under the bed and spray the front-facing CRC and radiator sides with a strong solution of Simple Green and water. I let it sit for 15-20 minutes and then I hose it down with a lawn sprayer from the back. I never see any oil on the CRC or the radiator and it never really seems that dirty, but I want to do whatever I can to get those temperatures down when I'm climbing those mountains and the dreaded check engine light comes on. My problem is that there are so many things in the way that prevent me from cleaning the whole surface area of the CRC and radiator. I'm wondering if those areas that are hardest to clean are what's really causing the problem. A technician at the Cummins shop in Albuquerque, NM told me that the only way to get those areas clean was to have the whole CRC and radiator removed for cleaning. I want to avoid that expense if possible.

- Rolf

[wolfe10]

Rolf,

Welcome to the FMCA Forum.

You have the best arrangement for a rear radiator configuration-- it is called stacked vs sandwiched. It is better, as it is only one layer thick-- radiator and CAC side by side.

And you are absolutely correct, the easy place to clean is in the center where the fan blades are the narrowest. But the fan blades sling the dirt to the perimeter, so the perimeter is where most of the dirt is deposited. No real special technique to cleaning it, just systematically cover the whole surface several times-- actually, until you notice that the effluent is clean.

And be careful with how long you leave the soap on the surface, you do want it to have time to loosen the dirt/oil, but NOT long enough to dry out on the metal surface.

Brett

[kenosavvy]

Brett,

Thanks for the reply. I still don't understand why my engine is called 'stacked'. Stacked implies one unit on top of the other, and mine is not that way at all, it's side by side. Anyway, do you recommend hosing the CAC and radiator from the front side while the engine is running? How would one do that, just point the sprayer through the fan area? Wouldn't the fan kick the water back at you? I've never done it that way and am not sure if I want to, but another user recommended it. And since the dirt is blown in from the front side, doesn't the dirt have to be removed from that side also (implying hosing from the back side)? And what things, besides the alternator, shoudn't get wet when hosing these areas from either side? Also, no mention of steam cleaning was suggested, but they do use steam to clean the CAC and radiator at the Cummins facilities.

- Rolf

[wolfe10]

Brett,

Thanks for the reply. I still don't understand why my engine is called 'stacked'. Stacked implies one unit on top of the other, and mine is not that way at all, it's side by side. Anyway, do you recommend hosing the CAC and radiator from the front side while the engine is running? How would one do that, just point the sprayer through the fan area? Wouldn't the fan kick the water back at you? I've never done it that way and am not sure if I want to, but another user recommended it. And since the dirt is blown in from the front side, doesn't the dirt have to be removed from that side also (implying hosing from the back side)? And what things, besides the alternator, shouldn't get wet when hosing these areas from either side? Also, no mention of steam cleaning was suggested, but they do use steam to clean the CAC and radiator at the Cummins facilities.

- Rolf

If you like, we can certainly call yours "side by side radiator/CAC" configuration.

More important than the term (indeed most "single layer" cooling systems ARE one on top of the other), there really is no difference in cleaning process. The operative here is that your cooling system is a SINGLE LAYER thick where sandwiched cooling systems are two layers thick.

Start by flushing from the BACK (reverse of air flow). Unlike sandwiched cooling systems you can flush a lot of dirt from the BACK. Then, clean from the front (access from bedroom or closed).

Always clean with the engine OFF. It would be very dangerous to do it with the engine running. And unless there is heavy grease that you are trying to remove, having everything hot just adds to the hassle factor.

Brett

[kenosavvy]

I cleaned my "side by side radiator/CAC" configuration today and found it dirtier than I thought it would be. The back side (viewed from the back of the motorhome) was clean, but peering between the fan blades with a trouble light showed that the other side was rather dirty. Like you said, it was dirtier around the perimeter of the fan blades than in the middle. I tried 3 applications of Dawn soap with a garden sprayer (1/2 bottle of soap with 1 gallon of hot water) and rinsed between each application. This cleaned a little but not good enough. I then applied 3 applications of full strength Simple Green. This worked a little better. I noticed that my fan blades were black, covered with dirt and oil. Would it help at all to clean the fan blades also? I was able to clean the engine side of the fan blades with the Simple Green, but I left the back side of the fan blades as is. That side would be difficult to clean. I really didn't see oil on the radiator/CAC, unless the debris I did see was dried so much that it didn't look like oil. But if there's that much oil on my fan blades, it must be elsewhere as well, right? I see a lot of black paint chipped off the fins where the water pressure from rinsing knocked it off. Would it help to touch that up with black paint or would that only be a cosmetic fix? I'm still wondering whether steam cleaning might help in combination with the soap and Simple Green.

[wolfe10]

kenosavvy,

Make sure that your crankcase breather is extended to BEHIND the fan shroud. That is the major source of oil mist. It should have been done already by your chassis maker.

If you do try to clean the back side of the fan blades (a good idea if you can get to them), make SURE to do all of them the same way. You do not want to unbalance the fan by cleaning some and leaving others "heavier".

Steam cleaning is a tricky issue. The PSI most of them work at make bending fins a real possibility. Repeated cleanings as you are doing is likely a lot safer.

I don't know the answer to your paint (cosmetic or necessary) question. Much of that answer would depend on whether they are aluminum or steel and whether you drive in or expose the coach to salt. Check with your coach builder on that.

Brett

[rev5299@aol.com]

Brett

What about the spray that they use on home a/c coils. I know you spray it on and all kinds of dirt will bubble out.

[wolfe10]

Brett

What about the spray that they use on home a/c coils. I know you spray it on and all kinds of dirt will bubble out.

Sorry, not a chemist, so I can't answer that one.

But I suspect there are different cleaning needs. I don't see A/C condensers being exposed to an oily residue. Dirt, yes.

[chucknewman]

Thanks Brett and others for the great information on radiator/CAC cleaning. I had Brazels do several upgrades last week and had them clean the rad/CRC when changing to new long life coolant. Dropped my level ground running temperature several degrees. Now I just need to keep them clean.

I could not get new thermostats in time for them to replace. I think I read they should be changed out every three years. That sounds excessive to me when you consider the LLC change period is 6 years. But I defer to your recommendations. If every three years, so be it.

And thanks also for the recommended PAC Brake upgrade. I notice significantly more compression at low RPM/speed conditions.

Chuck

[wolfe10]

Chuck,

It is Caterpillar's recommendation (in writing) to replace the thermostats every three years: http://ohe.cat.com/cda/files/517742/7/LEHT9288.pdf?mode

They are a wearing component-- metal on metal. Particularly if you just changed to ELC, I would go ahead and replace them just so you know the system is 100%.

Did you also check your belts and check water pump tension? Serpentine belt?

Brett

[chucknewman]

Both belts were replaced. I was starting to smell a slight rubber smell at the radiator outlet when starting the engine cold. Now lower temps and no smells. I will have the thermostats replaced when I get the valve lash done in a couple weeks at the Chico dealer.

Interestingly both belts had CAT part numbers but the Centralia, WA CAT dealer could not match or cross reference the number on the water pump belt. They did a physical match and it appears to be fine.

Chuck

[wolfe10]

Both belts were replaced. I was starting to smell a slight rubber smell at the radiator outlet when starting the engine cold. Now lower temps and no smells. I will have the thermostats replaced when I get the valve lash done in a couple weeks at the Chico dealer.

Interestingly both belts had CAT part numbers but the Centralia, WA CAT dealer could not match or cross reference the number on the water pump belt. They did a physical match and it appears to be fine.

Chuck

Chuck,

That is indeed puzzling, as the ONLY belt Caterpillar put on before shipping the engine was the water pump belt-- it "runs" ONLY the water pump on the 3116/3126/C7-- no chassis maker supplied components.

The chassis maker specs the A/C compressor and alternator, hence the serpentine belt is speced by the chassis maker. Could a Caterpillar belt be the same as your serpentine belt-- of course.

Brett

[mikey360]

After reading how dirty the CAC and radiator can get on these rear radiator units, I decided to see what I could do with mine. Warmed the motor up. First up, the service center stripped out the head of one of the motor access panel bolts last week doing the valve lash adj that should have been done years ago but never was (see my prior posts). Vise grips and lots of blue words later, I got the panel off. Fairly dirty motor in my opinion. Fan won't move (I was hoping it would have a clutch and would freewheel but no.) So squirted brake cleaner around the fins on the CAC as best I could. I estimate I could reach about 50 percent. Hosed that out with garden hose. Then I went to Simple Green. Didn't leave it on too long, then hosed that out. I'm concerned about the portion of the radiator I couldn't even see let alone get cleaned. If I take this to my service center , how will they clean it? I'm considering taking it there but I'm thinking of taking a photo of the rear radiator fins so if I get it back and they're all bent over, I'll have some proof it didn't come in that way. Any thoughts?

[wolfe10]

Be very careful using brake fluid or other really harsh cleaner. There are a lot milder dirt/grease cutters than brake fluid. A lot of the CAC's are aluminum. And with most sandwiched cooling systems (CAC if front of radiator) it is not really possible to clean from the back. You or someone else will have to clean from the front. Yes, I KNOW how awkward that is. The other option, which is a LOT more expensive is to pull the radiator so that you can "reverse flush" the CAC.

Brett

[kenosavvy]

I cleaned my 'side by side' radiator/CAC again yesterday. This time, I first steam cleaned the radiator/CAC from the engine side. Then I used Simple Green diluted about 4-1 in a garden sprayer with hot water, applied from the engine side again, through the fan blades. Then, after about 10 minutes, I rinsed from the outside using a garden hose and sprayer. Then I steam cleaned from the outside and rinsed again. The rinse water was pretty dirty from the first rinse, but not that dirty from the second rinse.

I found a hose the same size as the slobber tube and clamped it and extended it to the back of the motorhome. Now we'll see if the radiator/CAC stays any cleaner this year without that oil getting on the radiator/CAC.