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smlranger's avatar
smlranger
Explorer
May 30, 2014

Engine Coolant Color Change

I had my original coolant drained, system flushed and refilled with Fleetguard ES Compleat OAT coolant. This was done at my local Cummins
Coach Care center. I've had work done there and have no issue with the quality of their work and no reason to mistrust them. This was done one month ago.

ES Compleat OAT is a deep pink/light red color. I have driven the coach about 500 miles since the change and the coolant in the sight glass on my expansion tank is now light amber in color. I thought this was odd and called the Coach Care center and they are at a loss to explain this. I took a sample of the coolant to them today and they tested it with a refractometer and the test strips and it tested fine. Freeze point was -32F and the test strip showed all other measures fine (this was done in my presence). At this point they think the coolant is fine but say they have never seen this happen.

I have placed a call to Cummins Filtration and hope to get a call back from one of their tech folks. I have no reason to question that the coolant tests fine but am more than curious why this dramatic color change in this short time period.

I am curious if anyone here has heard of this.
Class A

7 Replies

  • wolfe10's avatar
    wolfe10
    Explorer
    May 31, 2014
    Thanks for the update-- never heard of that one-- good to know.

    Glad it was not "the usual suspect".
  • smlranger's avatar
    smlranger
    Explorer
    May 31, 2014
    OK, I had a long discussion with one of Fleetguard's Filtration tech folks this afternoon. He advised this was not an uncommon call for them in recent months due to some weak/bad dye they received. He advised if I got one of the batches of OAT with the dye problem, the coolant will change to a yellow or amber color. This can occur quickly or over a longer period. He said this affected coolant color only and had no impact on the chemical makeup or the effectiveness of the coolant. He assured me if the coolant was tested with their OAT test strips (they were, I witnessed that) and tested well, I had absolutely no issue. He advised me to test again in 6 months.
  • moisheh's avatar
    moisheh
    Explorer
    May 30, 2014
    I didn't know there were any test strips for OAT coolant???

    Moisheh
  • wolfe10's avatar
    wolfe10
    Explorer
    May 30, 2014
    Because of the residual water in those long heater lines and heater core, if you want a 50/50 mix, you HAVE to use coolant concentrate, not pre-dilute.

    So, after the final rinse (I use distilled water for final rinse) add 13 gallons of concentrate. Top off with distilled water-- you do not really care how many gallons it takes/how many gallons of residual water were in the system.

    The only way to properly use pre-dilute is to take off one of the heater hoses and use compressed air to blow out all the water in the lines and heater core. But, that leaves you with a LOT of air to purge from the heater circuit.
  • smlranger's avatar
    smlranger
    Explorer
    May 30, 2014
    wolfe10 wrote:
    The "usual suspect" when color is off is that they did not flush out all the old coolant, so you have some old and some new. Not a big deal if staying with the same coolant, but it IS a big deal of one is "regular low silicate for diesel" coolant and the other is an OAT-based coolant.

    I had this when we bought our current coach. Previous owner paid to have system flushed and change from regular to OAT (Cat ELC). Me, being a (not so) trusting soul, I pulled a sample-- color was not strawberry as it should have been, but strawberry with a green sheen! So, I flushed it myself and went back with ELC.

    For techs working on trucks, having this problem on a motorhome is not uncommon. Instead of 6' of heater hose, your motorhome has 50+'-- much harder to flush.


    I considered doing the work myself but I just did not have time before we leave on our first long post retirement trip. I discussed their flushing process with their service manager and he understood the challenges with getting a good flush with a class A motorhome (they work on a lot of motorhome). He even cautioned me that the labor would be pretty extensive due to need to do repeated flushing.

    My system is 26 gallons capacity total and they put 23 gallons of coolant in it. If they flushed adequately, the remaining 3 gallons (assuming CC's volume spec is mostly correct) should have been clear water. Considering what I paid to have this done, I would certainly expect them to re-do it if that is what is necessary. I will wait until I hear from Cummins Filtration. Perhaps they will pay for a chemical analysis of the coolant and, if it proves to be a mix of old and new, will support a re-do at no expense to me.
  • Ranger_Smith's avatar
    Ranger_Smith
    Explorer
    May 30, 2014
    I have never heard of that. I have the same antifreeze and mine is still reddish in color. Only,thing I can think of is they didn't get it completely flushed
  • wolfe10's avatar
    wolfe10
    Explorer
    May 30, 2014
    The "usual suspect" when color is off is that they did not flush out all the old coolant, so you have some old and some new. Not a big deal if staying with the same coolant, but it IS a big deal of one is "regular low silicate for diesel" coolant and the other is an OAT-based coolant.

    I had this when we bought our current coach. Previous owner paid to have system flushed and change from regular to OAT (Cat ELC). Me, being a (not so) trusting soul, I pulled a sample-- color was not strawberry as it should have been, but strawberry with a green sheen! So, I flushed it myself and went back with ELC.

    For techs working on trucks, having this problem on a motorhome is not uncommon. Instead of 6' of heater hose, your motorhome has 50+'-- much harder to flush.

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