49k on it. just took it in for an oil change and the antifreeze was approx 1/4 gallon low plus there is black sludge in the overflow bottle WTF....What could cause this ???

2006 Monte Carlo SS w/ 5.3 V8

 

I think I may have had a similar problem.

Check the water pump maybe? Mine went out cause apparenlty my coolant turned to jelly at 50k.

 

Wow, sludge in the overflow bottle. It must be junk!!!!

 

Not really a big deal and absolutely not enough to warrant calling something junk- LOL. Were they still using Dex-Cool on 2006s? It's probably just gunked up Dex-Cool.

If the engine went (bearing/big gasket/piston/waddever) at 49K- OK, maybe junk
If the transmission went- OK, maybe junk
If something major fell off the car (like a door or bumper)- maybe junk
Some dirt in the overflow tank- not really junk

I would recommend moving the sludge from the overflow tank to the trunk. It's better to have junk in the trunk then junk in the overflow bottle. My opinion only.

 

The sludge is def Dex Cool or as I call it Death Cool, it is designed for a sealed system, the overflow tank on our systems is not sealed.
What I have done with both Trans ams and my Monte is to flush the system and switch to traditional green coolant. Flush again relatively soon, and then flush again relatively soon. Make sure all the death cool is out. In one car I did it in the spring/summer so I ran mostly water between the 3 or 4 flushes. I kept doing it until I could not see any traces of Death Cool.

If you want do a google search on dex cool read about the lawsuits and how dex cool should be in a sealed system.

 

x2

Improper maintenance on the coolant = sludge and stuff going out on you.

I'm usually recommending people flush their coolant 30k miles or every other year. Did you own this car since new? Buy it used? Perhaps someone topped it off with the wrong fluid, maybe a thermostat was stuck and when it was replaced topped off with something wrong?

 

Something I still have to do pre-winter.

Would switching to a different coolant void my warranty?

 

Warranty, what is that, no just kidding.

You could check, but I would not think it would effect warranty at all, but that is just my guess.

Have you seen what death cool does http://www.consumeraffairs.com/autom...m_dexcool.html not sure how much warranty you have left, but it would not matter to me, that crap has to come out. I am a GM guy, but Dexcool was a big mistake by my boys.

 

Hi `Mike, did you buy it new or used ? Do you know how it was serviced ?

I believe that any vehicle that is not maintained can turn into problems, or junk...
I believe if a vehicle was treated like `junk it will be `JUNK
Do you know how your Monte Carlo was maintained/treated ?
Let us know `ok...Hope that you can resolve your issues with your `Monte and that your problems can be repaired/fixed/corrected...Please keep us updated `Ok....Thanks
Good Luck

p.s. Every Manufacturer's has a few lemon's : (
It's sad, but true : (

 

...Hi `Mike, I just read all your 24 posts and I can tell that you are unhappy with your 06 Monte, but I was happy to read that you are still looking for another year Monte Carlo...

I think you may have got one of the very few bad ones
I don't think your State Lemon Law applies with the miles that are on it now, but it's worth a search to check and see.

I do hope you can resolve your issues, or try to trade it.
Wish you better luck, and let us know what you decide...