Radiator Flush

[rsmolway@comcast.net]

I have a 2000 DP with a Cummins 300 ISC. I do not know when the fluid was last changed. I called TWO Cummins service centers in Fl.

Ctr #1 told me it needed a Fluid change and possibly a flush. ..[without seeing the coach] He said to expect the cost to be $500+..

Ctr #2 told me to drain a little fluid to see if was dirty and check the Ph. If the fluid was dirty it needed to be changed. If not, don't drain the radiator. If the Ph was off and the fluid was clear it only it needed an additive.

My Cummins book claims that it needs to be done every two yrs or 24,000 miles

When I checked the fluid it was clear [ green color] and the Ph was perfect.

My question is which Cummins service center should I believe ?? To Flush or not to Flush..that's my question ?

Thanks

Capt. Ron

[wolfe10]

I have a 2000 DP with a Cummins 300 ISC. I do not know when the fluid was last changed. I called TWO Cummins service centers in Fl.

Ctr #1 told me it needed a Fluid change and possibly a flush. ..[without seeing the coach] He said to expect the cost to be $500+..

Ctr #2 told me to drain a little fluid to see if was dirty and check the Ph. If the fluid was dirty it needed to be changed. If not, don't drain the radiator. If the Ph was off and the fluid was clear it only it needed an additive.

My Cummins book claims that it needs to be done every two yrs or 24,000 miles

When I checked the fluid it was clear [ green color] and the Ph was perfect.

My question is which Cummins service center should I believe ?? To Flush or not to Flush..that's my question?

Thanks

Capt. Ron

Captain Ron,

Clarity and testing (test strip for SCA, pH and Freeze Point) will NOT, repeat NOT give you enough information to risk your engine and cooling system with worn out coolant.

Go with Cummins recommendations for change interval with standard "low silicate coolant for diesels with SCA" . If you go to an extended life coolant follow the coolant manufacturer's recommendations.

Radiators and engines are a LOT more expensive than coolant!

If your present coolant is clear, tests OK with the test strips, there are no deposits visible in the radiator AND YOU KNOW WHAT TYPE OF COOLANT IS IN THERE AND STICK WITH THAT CHEMISTRY, you can get away with a single flush with distilled water, and not need to use any cleaner, etc.

If you are switching coolant chemistries-- like going from standard "low silicate coolant for diesels with SCA" to an extended life (OAT-based) coolant that has longer change interval and does NOT require testing and addition of SCA's you will need to use a cooling system cleaner.

BTW, changing it yourself is not that difficult, though it is time consuming. If you are interested, let me know and I can post details.

Brett Wolfe

[svkatahdin@yahoo.com]

I don't know about anybody else, but I would sure appreciate the information. My Safari has a Cat 3126. Many thanks.

[wolfe10]

I don't know about anybody else, but I would sure appreciate the information. My Safari has a Cat 3126. Many thanks.

Same issues here. The chassis maker, not engine maker chooses the coolant. So you will need to check with Monaco for what brand they used if you need to top off what is in there. And, it will be a regular "low silicate for diesels coolant" that DOES require SCA testing/adding.

But as stated above, if over 3 years old (from date of chassis manufacture) you real decision is whether to replace the old coolant with "low silicate for diesel coolant with SCA" or switch to a long life coolant that does not require testing and adding of SCA's.

If you choose a long-life coolant, since you have a Caterpillar engine, I would go with Caterpillar ELC (Extended Life Coolant).

Caterpillar also calls for (in your Caterpillar Owners Manual) for thermostat changes every three years. Coolant change time is a good time to do this. Your 3126 has two thermostats.

If you need instructions on changing coolant, let us know. It IS time consuming, but very low tech.

Brett Wolfe

[svkatahdin@yahoo.com]

Thanks, Brett, I would appreciate the coolant changing information. Any tips on the thermostats would also be helpful. Thanks again.

[wolfe10]

Here is an article I wrote for the Caterpillar RV Engine Owners Club Newsletter

Cooling System 101

I just changed out my coolant to Caterpillar ELC and replaced all water hoses and belts. Thought I would share the experience.

To my knowledge no chassis/coach maker is using ELC—so all are “low silicate coolant for diesels†with included or added SCA. Coolant needs to be changed per manufacturer’s instructions (usually every 3 years). Additionally the SCA, pH and freeze point need to be checked on regular intervals using SCA test strips and SCA added as needed. The test strips are inexpensive and easy to use (we check the SCA concentration in all coaches at Cat RV Club Rallies). When either the time lapses (time starts when coolant installed in cooling system, NOT when purchased) or testing reveals an out-of-line conditions like pH or freeze point, it is time to change it. You can avoid all the testing and SCA adding, and go to 6 year change intervals by going to Caterpillar ELC and get better cooling system protection as well. Whichever coolant you choose, most of the steps are the same. The job is reasonably time consuming TO DO RIGHT, but low-tech.

Turn dash heater to full hot for the rest of the procedure—fan off. With the engine cold or at least cool, drain coolant. On some, there is a drain ****. On others, pull the lower radiator hose. I catch it in 2 Rubbermade 10 gallon storage bin lined with black trash sacks so I do not even get them dirty. At the end of the whole process, use a coffee can and funnel to pour old coolant into new coolant/water containers for recycling. Our city maintenance shop recycles coolant for free.

Refill cooling system with tap water. IMPORTANT: Be sure to remove any air lock from the thermostat housing. Some systems have a hose set up for this—on ours I just loosen the coolant line to the air pump and bleed the air out. Allow engine to warm up (using the cruise control to select idle speed of 1,000-1,100 speeds this up). Run for about 10 minutes at regular temp. If the temp gauge does not rise as normal, you likely have an air block and need to bleed the thermostat housing. Allow engine to cool 20-30 minutes and drain again. Repeat until the color is clear.

At this point, if this is the first coolant change on a 2-3 year old coach and you are not changing coolant brands/types, skip right to “Last rinseâ€. For older systems or for switching types of coolant, add a Cooling System Cleaner such as Cat Fast Acting Cooling System Cleaner 4C4611. Follow directions. Run, allow engine to cool, drain and again flush until effluent is clear. The flushing is markedly sped up by pulling off the heater hose (usually 5/8 to ¾†lines going to dash heater/motor-aid water heater, etc from the water pump. Put a hose nozzle in the hose and let it run until what comes out is clear. Run the engine to temperature at least once with tap water.

If your hoses are over 3-4 years old, this is a good time to change them as well (before last rinse). Same for thermostat(s).

Last Rinse is with distilled water. At $.62/gal at Walmart, it is silly to skip this step and leave your system full of high-mineral content water (there will be several gallons of residual water that you can not easily remove). Run engine for 10 minutes after getting to operating temperature. Cool and drain. Also drain and flush your coolant overflow container and refill with new coolant/distilled water.

Add the proper amount of Coolant CONCENTRATE (NOT PRE-DILUTE) to make 50% of cooling system capacity. My cooling system is 18 gallons, so I added 9 gallons of Caterpillar ELC CONCENTRATE (119-5150) (plus one for overflow container). Top off with distilled water to achieve your 50/50 mixture.

This is also a good time to clean the OUTSIDE of the radiator/after-cooler whether you have rear or side radiator. On rear radiator, most if the debris will be on the FRONT of the after-cooler (accessed from under the bed). On side radiators, most debris is on the outside of the after-cooler (side of coach). If it is just dirt, a hose and regular nozzle is all you need. If greasy or oily, use Joy liquid (dish washing detergent) in a spray bottle. Be SURE to rinse it off completely. You need to insure that the perimeter is as clean as the center. Ya, I know it is easier to see the center, but the fan blades "sling" the dirt to the perimeter.

Check belts while you are in there.

And Caterpillar recommends changing the TWO thermostats (they are in one housing) every three years:

Caterpillar Maintenance Recommendations

Brett Wolfe

[svkatahdin@yahoo.com]

Thanks a lot, that's just the information I needed.