Is it possible to clean the coolant reservoir?

[ChevMali99]

Yes it is.


Through my years of owning a 99 Malibu 3.1 the yearly ritual to pass NYS inspection has been a thing of constant experiment. As a result, I learned that clearing the PCM, disconnecting the battery before reconnecting a cleaned up EGR , filling up with premium gas & fuel injector cleaner, will remove all pesky emission codes 99% of the times. Today, because I was not able to see the coolant in the reservoir and the light indicating coolant shortage remained on I decided to try my hand in cleaning it.



As you can imagine, coolant gunk was plastered inside. After removing reservoir and safely collecting all the antifreeze (yes a mixture of Dexcool and Prestone all makes, all models , all colors), I filled it with hot water first to remove whatever could easily be removed. Then, after trying different base solvents, I noticed that the combination of WD-40 & Oxyclean detergent worked like a charm! It was incredible! I mixed about a half of cup of the concoction, poured it into the reservoir and shook it as if I was a bartender, I repeated this for about 5 times. I could’ve stopped after the 3rd time but I wanted to see how much more gunk I could’ve gotten out. The gunk turns into that milky oily liquid people cite when the antifreeze is leaking or mixing with oil. DO NOT LET THAT STUFF GO DOWN THE DRAIN!!! Make sure you have a bucket to collect the waste.



At any rate, after the 5th time I had enough and went onto rinse the whole thing with vinegar & water then water alone; to neutralize the WD-40 and get the smell out. I sat it there for a while and installed it. Done – the coolant is back and I’m able to see it through.


The coolant is low indicator light is still on… it comes and goes, but all in all it was a good day of cleaning and seeing clearly now.

[Tech II]

If the coolant sensor is in the reservoir, with the coolant full, give the sensor a couple of love taps with the handle of a screw driver to get that light out......