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Old 10-02-2015, 05:53 AM   #1
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Lightbulb Coolant

Just bought a 2003 Newmar Dutch Star with a Cummings ISC 350hp. I owned a gasser before this. I noticed there is no sign of coolant in the overflow reservoir when the engine is cold. Should I add coolant and what type?
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Old 10-02-2015, 07:15 AM   #2
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I would recommend using HD Diesel Coolant which is low silicate. Finial Charge is one make. Should check the DCA level which is important with wet sleeve engine which your ISC is. There are test strips you can purchase at Cummins or other diesel parts stores. Since this Newmar is knew to you should get additional information on this important information on HD diesel ownership.
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Old 10-02-2015, 08:35 AM   #3
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I agree with Tom's input. If you do not know by the previous owners documentation when the coolant was last changed. A good investment to have the system flushed, and a complete change over to Final Charge (or similar, we use Final Charge as we can usually always find it in larger truck stops stores). Have the thermostat, and radiator cap changed at the same time. The shop should change your coolant filter over to a dummy filter, one without SCA involved, at this service. And, if the radiator shows any signs of crud, a good cleaning will keep everything cooling easier.

To keep things simple, we also had our generator coolant changed to Final Charge. And only carry one gallon of the 50/50 mix to use if needed for topping off of both engine and generator coolant.

Enjoy the ride. Oh, and yes, that coolant tank should have coolant in it. Many coaches have several gallons of coolant in a tank, and when low, will send a warning to the engines ECM. I know of some whose ECM's have gone into protection/limp mode, due to low coolant levels. (May not apply to your coach.)

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Old 10-02-2015, 08:57 AM   #4
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Mine uses Chevron Delo ELC red coolant as recommended by the cummins shop in my area. There have to be coolant in the reservoir when cold and there should be a light.
Monaco Cayman 34 PDD 2003 Cummins ISB 300 HP on a roadmaster, 5 speed Allison.
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Old 10-02-2015, 05:25 PM   #5
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Do you have any maintenance history on this coach. Has the coolant filter been changed on a regular basis (~1 time per year).

If not I would consider taking a coolant sample and sending it in for analysis. I used this company for mine
Buy an Engine Oil Analysis Kit Today | Engine Oil Analysis Service

Took about 4 days after I sent the sample in. The results will tell you the quality of the coolant you have in your system. In particular it is important to watch PH, SCA levels, freeze temp and also look for any contamination.

If the coolant is good add a compatible coolant, if it isn't change it.
Jim J
2002 Monaco Windsor 38 PKD Cummins ISC 350 8.3L
2005 Jeep Grand Cherokee w/5.7 Hemi
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Old 10-02-2015, 11:29 PM   #6
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Cummins just rebuilt our ISX and used ES Complete OAT coolant so no more messing with DCA.
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Old 10-03-2015, 07:13 AM   #7
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If by "overflow reservoir" you mean the tank w/pressure cap/standard radiator cap there should be coolant in it. Mine is metal w/a sight glass for minimum level. If you mean a plastic bottle like cars have with a non-pressure pop off cap then the pressurized tank should be full and the non-pressurized bottle should be at 1/3 to 1/2. The presurized tank is the surge tank, and the non-pressurized tank is the recovrry/overflow tank.
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Old 10-04-2015, 05:39 AM   #8
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Thanks for all the comments. The plastic overflow is bone dry, the pressurized tank is full. Since a don't have good records, other than proof of oil changes and filter changes in both engine and generator probably best to find somewhere to get it serviced. At least I have the cold Ohio winter to learn about diesels.
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