Coolant change - can you explain the mystery?

[RedCorvette]

I just had my coolant drained and filled twice but something strange happened and I want to know what everyone thinks.

Firstly, it's a Ford on a 5 year / 100k interval.

I forgot the 5 year bit, and so the car had the first drain and fill done at 8 years / 70k.

Prior to it being done, the color in the reservoir was good, and there were no cooling issues. The heater blows hot very quickly. This has not changed.

For the first drain and fill, I gave 2 x gallon jugs of G-05 and distilled water to the shop. From what I got back and how it was explained to me, I can't tell exactly how much of each was used, nor could the manager, so we agreed to do it again. But my concern was based on the fact that they seem to have used a lot of coolant and not enough distilled water.

So 2 weeks later, they did it again, this time keeping track of the quantities. Out of a 10.6 quart capacity, they drained as much as they could and then filled up 6.5 quarts of 50/50 mix to get to the full line in the reservoir.

The strange thing that happened though is that when I was shown the bucket with the drained coolant, it came out a brown color. Not thick, just brown. This was strange because I saw some of it coming out (steaming) during the drain process, and it looked quite clear and thin at the time.

Any thoughts on what is going on? Everything else is mechanically absolutely fine. No oil leaks. The coolant has always looked nice and clear in the reservoir, before, during and after all this work.

Apart from the possibility that there was (and maybe still is) some gunk in the system / radiator and the second hot drain got it out, all I can think is that the bucket was already dirty.

If the system was dirty, why didn't I see it in the reservoir during the intervening 2 weeks?

 

[Donald]

First looking at a stream of coolant or oil is problematic. Getting some in a glass jar is a much better way. I think you have got to assume that who knows what was done the first time. Do you think the brown color was a layer floating on top or was it the real color? Maybe the second drain was done in a better way. Maybe they drained the block also rather than just the radiator.

Lastly the G-05 you brought them might be a different color than what was in the car. I think Zerex G-05 is a different color than Ford G-05. Zerex seems to be a very light color, almost no color.

 

[Corvette Owner]

I agree, coolant often takes on the color of the container it is drained into. I always use a coolant tester to see what the freezing point is and what the color is.

 

[RedCorvette]

Re the stream, understood. The stream was actually draining Zerex G-05 and looked clear. However, in the white bucket it was brown. It might have been a layer. It did have that quality about it ie it wasn't thick, just colored.

As you say, new Zerex is light in color, lighter than Ford G-05.

This second drain and fill was a simple one, nothing came out of the engine block, but air was used to push out as much as possible. Perhaps that was what caused a layer of brown to end up on top of the drained Zerex.

Both the used and new 50/50 G-05 / distilled water were in seperate white buckets next to each other so it was easy to tell the color difference ie the used was brown and the new was gold color.

 

[oilstudent24]

Would this dealer have used a BG or similar multi-use fluid. I know a Ford dealer that does this for ATF exchanges with a machine. is it possible that is the color of their new non-Ford Fluid?

 

[crazyoildude]

maybe the container was dirty?

 

[RedCorvette]

They used Zerex G-05 the first time and Ford Premium Gold the second. These were the first and only coolant services after factory fill, excepting any top ups.

For me the main question is whether this is explained by the fact that my factory 5 year / 100k coolant was first changed after 8 years / 70k? Could those extra 3 years have created gunk in the system that the first drain and refill with Zerex G-05 cleaned out in the two weeks it was in there?

Would a hot draining of coolant lead to more gunk coming out of the radiator?

But since the coolant in the reservoir never turned brown in two weeks, the idea that the Zerex did some cleaning seems unlikely to me.

So if these reasons don't seem likely, then I'm assuming it's a dirty container.

 

[antiqueshell]

I'd say dirty container or perhaps it could be residue from the rubber hoses. I wouldn't worry about it.

 

[mechtech2]

A small diameter stream will look clear.
A large concentration will be darker.