Click the image below to go to our message boards

RV Forum Commuinity

Our sponsors

Sponsored by Fridge Defend

 Sponsored by Winnebago Industries

Sponsored by Shattersafe

Sponsored by FMCA

 Sponsored by RV Life Magazine

 Sponsored by RV Park Reviews

 Sponsored by RV RV Trip Wizard

Sponsored by RV Upgrades

Sponsored by Composet Products

Cummins antifreeze maintenance

by Steve Pally

Description of antifreeze changeover for a Cummins engine as well as DCA maintenance.

I changed the coolant as prescribed, after two years, in our American Dream, which is powered by a Cummins C8.3.

The info in the cummins manual was sparse and the details of location of petcocks did not correspond to the way Spartan built my engine setup.

There are TWO draining petcocks: one at the aft bottom of the radiator and the second on the lower engine block. From under the coach if you look to the rear of the oil filter, toward the pulleys the petcock is there.

After draining about 7.5 gallons, I disconnected the hose at the bottom of the overflow tank. I noticed additional draining. I started up my prtable compressor and blew air into the hose and recovered another gallon for a total capacity of 8.5 gallons.

As there is no air vent petcock in my set up (contrary to the cummins manual but confirmed by Spartan) the tech recommended I disconnect the 1/4 ich pipe leading to the top of the rad for air venting while filling. This takes a 9/16 wrench.

I decided to use Fleetguard Compleat Antifreeze since the cost difference between untreated antifreeze and Compleat after factoring in the cost of the DCA concentrate or the treated filter was marginal.

In addition Compleat indicates it is "low Silicate" which I am told is important for our engines.

There was a service bulletin issued by Cummins recently that advises against using Caterpillar (Texaco) long life antifreeze as it is incompatible with DCA.

There is contraversy over whether or not this is true, but as my engine is not an experimental engine, I decided to go with the OEM product.

By using Compleat which is pre-charged with DCA, I installed a new 0 unit DCA coolant filter. I prefer to test my DCA level and adjust using a separate bottle of concentrate. The option is to use pre-charged filters containing 2, 4, 6, 8 or 12 units of DCA per gallon of antifreeze.

It should be mentioned, as there is no mention in any Cummins or Fleetguard literature that DCA levels are calculated in units per gallon. You must know the capacity of your particular cooling system to correctly calculate the amount of DCA to add to keep the level between the recommended 1.5 and 3.0 units per gallon.

I filled the system, and as soon as the coolant leaked from the tube I disconnected from the top of the rad, I reconnected it.

Contrary to reports the blue Compleat is not visible through the accumulator tank sight glass I found the blue color to show very clearly.

While the system is empty, it would be a good time to remove the sight glass and clean it as it tends to accumulate some sludge with time. If the sight glass is beyond salvation, a replacement is easily available at truck parts stores or Cummins Dealers.

When removing the coolant filter, check to see if the shut off valve which supplies the filter, at the top of the structure the filter screws into, can be turned.

For a time, Cummins was installing plastic valves which tend to get stuck and break. Cummins will replace the plastic valve with a stainless steel valve at no charge in about an hour. You need an appointment and tell them you want the new stainless steel valve.

As a preventative measure, it's a good idea to spray a bit of WD-40 on the top of the valve and turn it back and forth whenever you check your oil to keep it moving freely.

The air locks dont get out until the thermostat opens, when it gets hot, so the engine should be run with the red cap off for several minutes to allow the antifreeze to circulate and get the air out.

Once the cap is back on, the system should be checked for leaks. It's also a good time to clean the debris out of the side mounted rad.

Some earlier (circa 97- 98) American Coaches were built with large openings in the rubber surrounding the radiator. This will be corrected at the factory by closing these openings with additional rubber to improve cooling efficiency.

Also some early ISC engines were recalled to upgrade the cooling system where the entire radiator configuration is modified to improve cooling efficincy.

Hope my experience can be useful, and I would welcome comments or suggestions on how the job could be done differently.

It took me the better part of the morning to do the job, as I had never done it before. Now that I know where everything is located I would think it would be a two and a half to three hour job.