Things to look out for in DexCool coolant?

[OpenClose]

I'm driving a 1999 Buick Regal GS with the supercharger. I got it at 113k a couple years back, and have since done all kinds of maintenance and repairs to keep it in top shape.

However, I have done about 3 or 4 coolant changes since I got it, because the first time I did a coolant change, it came out with a lot of brownish-orange chunks. So I did a replacement the first time. Then the second time, I went a little more in-depth:

- Drain old coolant
- Run car with heat on max and engine up to temp, running a hose into the radiator to flush the engine and heater core
- Drain remaining water
- Replace with distilled water and prestone cooling system flush.
- Run car like this for a while
- Drain yet again
- Replace with 50 50 mix of Dex and Distilled Water.

By the end, everything was draining clear. But there still seems to be a bit of sludge built up on parts, especially the reservoir.

But not only that, there are black dots in the coolant that show up on things like funnels when inserted into the coolant. There is no oily or rainbow film on the surface of the coolant, so it doesn't appear to be oil. I was thinking it could be bits from hoses, or old, thickened coolant that was stuck inside parts (like from stop leak?).

Anyway, what are some things to look out for in Dex-Cool or any other coolant? What are they symptoms of? Things like rustiness (hard to see in orange dex cool), cloudiness, black dots, oil films, sludge, and anything else. (I also heard one about coolant voltage)

I would like to be able to diagnose and troubleshoot issues on my own in the future.

 

[69GTX]

The only thing I watch out for are air leaks, change the Dex-Cool periodically as required, and ensuring it doesn't get mixed with the regular green stuff. Fwiw, when I bought my '99 5.7L with 12K miles 3 years ago I was pretty sure the original owner never changed the coolant. After all, it was rated for 100K miles. I checked voltage on it and came out bad. The coolant itself was a murky-looking brownish orange. Mostly brown though.

Upon doing a flush it was amazed that the radiator and everything else I could see was clean as a whistle. No brown chunks, white crud, sludge or other signs of problems. That was possibly 13 year old coolant. Since the system had no air leaks that would have been a big plus. I have stayed with the Dex-Cool. Will be doing drain/fills or flushes every 3-5 years.

 

[ls1mike]

I think you might want to get a UOA done. You need to verify that the intake gasket is not leaking. You can pull the reservoir and clean it not a big deal.

Can you see if you have the metal intake gaskets? You can look between the intake and head. The gasket should look silver.
If it black those are the plastic ones and should be replaced.

 

[OpenClose]

"Can you see if you have the metal intake gaskets? You can look between the intake and head."

Is this something I can check without taking off the supercharger and manifold?

 

[ls1mike]

Yes you might have to take the engine cover off. Just look at where the intake meats the head.

 

[901Memphis]

I gave up on cleaning my reservoir and just replaced it. The regal doesn't have a pressurized reservoir so I'd switch to something else like I did on my Buick, switched to G05

 

[KrisZ]

Could also be the residue from the stop leak goo. People use this stuff quite often.

 

[OpenClose]

"Could also be the residue from the stop leak goo. People use this stuff quite often."

And that's the thing. The sludge hasn't come back TOO bad. The coolant comes out rather clear as of Monday when I changed my thermostat. The black dots never increased. They actually disappeared after a while.

So I feel like this is a good possibility. But the existence of sludge at all shows there may be extra air in the system, and could point to intake manifold gasket failure. Though I'm not sure how UOA would help, here, because I wouldn't think it would leak into the oil system.

 

[ls1mike]

It was how I caught it in my 1998 Regal GS. The gasket from the head to the intake will leak coolant into the lifter valley. The lifter valley is full of oil which drains back to pan. It is important to have it done as left unchecked you will spin/ruin a bearing.

 

[Blinker]

Ive have those black dots in my overflow tank as well. Its been like that since new and they dont float, they stick to the sides of everything and are impossible to get off. Possibly the guy plunking coolant sealing tabs on the assembly line put one too many in it? There are other forums ive read with ppl talking about this as well, it happens to every manufacturer and seems to happen to a smaller percentage of vwhicles.

 

[artificialist]

I would sometimes see them in the reservoir on my 2003 Saturn ION.

I always thoughts they were tiny bits of radiator hose, but I never knew for sure what they were.