I have always maintained all of my vehicles religiously & thus I keep them for a very long time. I cannot afford to do otherwise. In years past I did most everything myself. With the newer vehicles that has become more & more difficult it seems. Currently we own a 99 Blazer, 96 Silverado, & an 85 Jeep Cherokee. The radiator fluid was the nice clear Orange on both the Silverado & the Blazer until last year on the Blazer only. I had to take it to a chain operation to have the regular radiator flush & new Dexron. After they finished I observed a mass of Black oil like Gook in the radiator reservoir. I asked them to clean it as it seems it should have been part of the flush that I get a clean reservoir & radiator back. They would claim to clean it, but did not seem to & then claimed it could not be cleaned. So I cleaned it myself. Then later we had another radiator/drip/smell issue & I took it to the folks we take things to if I have some real mechanical issues that I am unable to address either at the time or for whatever reason. They are supposed in be the best in town. We went through several issues with them this time as well & are still working on an unsolvable issue regarding the radiator smell that they again checked out yesterday with pressure & visual & said they could find nothing, but advised me to get a new radiator cap, which I did. To make the long story short along the way of their replacement of the intake manifold gasket, water pump, etc. I observed the oil like gook in the radiator itself (no problem with crank case oil. I checked & they checked) I asked about it & they just said "that is a real problem with these vehicles". I want to know how I can get that stuff out of my radiator & coolant system for good in the Blazer. I cannot believe that is just a problem in those vehicles as I kept it looking good for years until the chain operation worked on it & my truck is older than the Blazer & it still looks good. Something is going on & I have maintained it religiously. Can anyone tell me what is going on & what I can do to get the system back to the way it was & get rid of that stuff for good. It seems neither the requested flush, my subsequent cleaning of the reservoir after all, the replacement of fluids shortly thereafter to address the leakage issue (intake & water pump & apparent ongoing) that you would think would have made that a big part of the operation has been successful in getting it back to the way it was. Thanks.

 

They put green coolant in with your DexCool. Thus set up the science experiment. Of course they denied it what do you expect.

 

That I actually caught both of them doing. The deal now is, how do I get rid of the stuff, permanently, once & for all, & get it back to the way I had it as there doesn't seem much real value unfortunately or ability in pursuing it further than moving forward.

 

First have them remove the radiator and heater hoses and replace them. Make the thermostat stick on the open position and run with water til the check engine light comes on the code will be too long before operating temp. Drain that water, fill and have them doit again, and again. And again. Have them install new upper and lower rad hoses and heater hoses and the correct DexCool. Run that combo for about 150 mi. Then have them drain and discard the coolant and replacewith new. Have them read the label aloud in front of you.

 

Ok, I have been back to the mechanic again twice. The are supposed to be the best in this town, better than dealer allegedly for GMC products especially. The have pressure tested over time twice, no issue found with core. They have looked for the normal evidence areas for evidence of heater core failure, etc. etc. Leakage has indeed slowed considerably (since weather warming), but it is still leaking ever so slightly. Replaced radiator cap at their advice. Smell is still there, but considerable less & fog is not near as bad with just air running now rather than heated air. Still they cannot find the leak after testing multiple times, replacing intake gasket, water pump, etc. as previously noted. Replacement of heater core is serious (relative to labor costs or my time costs if I were to attempt it on this modern vehicle. Any ideas, suggestions, thoughts, methods to test core with complete & all certainty? Also the driver's side heated mirror now has turned amber for half of it & cannot be seen through as it was before after they worked on it. They say they did not do anything to cause it. Looks like I will have t replace that mirror. How difficult is to replace this sort of mirror in these modern vehicles? I used to be pretty handy & mechanically inclined as noted & could perform any major task. However, on these modern cars I cannot seem to do much of anything & everything just about is a fog. Thanks a billion. 99 Chevrolet LS Blazer, 4 wheel drive, Heavy duty & winter package.