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ROYBUCK's avatar
ROYBUCK
Explorer
Sep 26, 2013

Coolant Change

I am in the process trying to decide what type of coolant to put in my Cummins ISC. I currant have the ES compleat Glycol Extended Service I know how to flush if going back to the same type of coolant, what type of flush if I go to the ES Compleat Oat.

Thanks
Roy

7 Replies

  • Moisheh, Just curious as to what OAT did you switch to? Do have a CAT or Cummins? My local Cummins dealer has the CAT coolant EC-1 (ELC) that is shown in this chart:

    http://www.boyerpetroleum.com/documents/peak-af.pdf

    I think that I am going to change over to the EC-1 rather than deal with the SCA's and having to check the levels with the test strips. Thanks.
  • Don: Truckers mostly use that coolant because it is cheap and they lose many gallons of coolant every year. BUT for Rv'rs I think the OAT is the way to go. Once you switch over there is no need for SCA and test strips. The price of OAT has dropped an it is good for about 5 years before you have to add the extender. Then you are good to go for 5 more years. Many of us on the IRV Monaco forum have switched and are quite happy. The test strips for the regular diesel coolant age after about 4 months and even then some that are supposed to be fresh do not work properly. A real pain.

    Moisheh
  • You can buy Alliance anti-freeze (DCA2?) at Freightliner for about $11/gallon for the full strength stuff, that must be mixed. From the size of the stack of cases on display I would imagine this item is Freightliner's biggest seller.

    I once studied the coolant issue, at some depth, for my 1995 8.3 Cummins powered Monaco. I assembled a large amount of documentation for my evolving point of view but my old computer blew up and I lost all that data.

    The big picture is that coolant has evolved primarily because engine manufacturers tried to keep this category from being a non-patent protected, low priced, commodity business that they couldn't make big margins on.

    I specifically remember reading a Cummins tech bulletin that stated, in the small print, that DCA2 was unsurpassed in terms of cavitation (pitting) protection. Everything else (Molybdenum - OAT)has been added as an inducement for you to pay multiples of what a gallon of DCA2 retails for.

    If you got to Freightliner and see what they sell the most of, you come to realize that the over the road truckers use mostly DCA2. The reason is simple: the protection is the nitrite and the nitrite is measurable and adjustable.

    When you move up to the DCA4 or OAT stuff you end up with a lot of stuff that is not adjustable (cannot be measured and added as needed).

    I am not any kind of expert but the engine manufacturers' desire to steer people away from simple, cheap, commodity anti-freeze is certainly understandable. Couple that with what the truckers really use (DCA2) and you have the basis for a more informed point of view.
  • This site is a wealth of information. I've been reading a lot of posts about cooling system anti-freeze. I have a 2007 Fleetwood with a C-7 300 Cat Motor. I Came back from Boulder City on Monday and 1 mile from my house my low coolant light came on, then check engine light, then the MH went into "protective mode"...little power, could only go about 15 mph. I made it to the house while checking the engine temp...never got above 200 deg. Coolant was flowing out when I parked. My overflow tank hose came loose from the bracket mount and a section of it was cut by the fan blades. I bought a new section of 3/8" hose (actually fuel hose) and will try and find a new way of mounting a bracket or clamp so that this does not happen again.

    Here is my dilemma...there is a sticker on the radiator that indicates that the system is filled with Alliance Fully Formulated Heavy Duty Coolant (Pre-Charged with SCAs). I am not sure how much fluid was lost (probably a lot). Since my MH is 6 years old and has 16k miles on it, it probably is due for a coolant change anyway. Should I refill with the Fleet Charge (with SCAs) or flush and switch to the Cat EC-1 (ELC) with embitterment? From what I read above, flushing and changing over will be somewhat of a task...is it worth it?
  • Dennis,

    Actually most coach owners, even with just basic shade tree mechanical skills will do a BETTER job than most dealers.

    Most of the difference is in the time just waiting for the engine to warm up and cool down.

    I have posted this before, but here is the process-- you will see there is a lot of waiting involved-- unlikely to be done at a dealership. And, as far as recycling the old coolant, I would call your city's vehicle maintenance department to see if they will accept your old coolant. If not, I suspect they can recommend a facility that will accept it.


    Cooling System 101

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

    To my knowledge all RV manufacturers use a “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. When either the time lapses (time starts when coolant is 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 an Extended Life Coolant 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.

    First step is to determine your total cooling system capacity. Your chassis maker or coach maker, not your engine manufacturer is the proper source. Then buy enough coolant (concentrate, not pre-dilute) to make up 50% of that volume. If going back with a coolant that requires additional SCA, purchase that as well. Also purchase 1.5 times system capacity of distilled water for a final flush plus final fill (50%). Also a good idea to change the engine thermostat and thermostat gasket as these are a wearing component and it involves very little more work while you are there. I know Caterpillar recommends thermostat (they call them regulators) every 3 years.

    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 cock. On others, pull the lower radiator hose. Two Rubbermade 10 gallon storage bin lined with black trash sacks so they don’t get dirty work well. 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 effluent 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 rinse”. For older systems or when switching types of coolant, add a Cooling System Cleaner. Follow the 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 it comes out 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. So for a cooling system with 20 gallons capacity, add 10 gallons of Coolant CONCENTRATE (plus 1/2 overflow container capacity). Top off with distilled water to achieve your 50/50 mixture—it doesn’t matter if you only have to add 1 gallon or 10 of distilled water, you KNOW you have the proper 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.
  • Personally, from simply an economic perspective, I would have my local Cummins dealer do it. Then you know it's done correctly. The OAT is supposed to be the last flush you'll ever do, so it's a one time shot. If not done correctly, the end result won't be pretty....just sayin....Dennis
  • Roy,

    Check with Fleetguard. I know that Caterpillar has a specific flush that must be used when switching from "regular diesel coolant" to their OAT-based coolant.

    Suspect Fleetguard/Cummins has one as well.