Funny thing is a pressure test was done at a local independent shop and by the dealer. I don't understand why they couldn't find a leak. However, I will say that when I first noticed that I was loosing coolant, it would take a couple of months before having to add more. In the end, I guess it was much easier to detect the leak.

 

Sometimes the leak will only show up at a certain temp...When I had cooling problems and couldnt pinpoint it, would block off the rad and get it heated up, then check it..had one motor where it had a horz crack in #8 cylinder that wouldnt cause problems until it got over 180 deg....heads, gaskets, intakes and such all expand and move around as they heat up..so normal idle temps may not show anything

 

Had mine in at the dealer for free oil change tire rotation etc.
Has them check everything that I could think of about the temperature moving around mainly in cold mornings.
Of course it would not ho over 205 fir the tech but no hidden codes etc.

 

Could that black stuff been part of the rubber that is part in thermostat

 

The black stuff I had in my radiator I doubt was from the thermostat. There was way too much of it. There was hundreds and hundreds of pieces of it that I saw.

 

Was DexCool in it? That sounds like nasty corrosion caused by the "green/yellow stuff". When DexCool over heats it gets chunky, but still the same color.
If there was that much in there I would be running clear water for a couple of days then flush again, repeat until no black chunks, then fill with 50/50 DexCool. Because the flushing obviously loosened stuff up, might be more almost loose enough.

You don't want to hear my other thoughts; head gasket or exhaust valve.

 

Just a quick update on my coolant situation which may help someone searching for an answer in the future or help even me if I forget where my notes are on this.
After I received mine back from the dealer the coolant level was about 1-2 inches higher and seemed to stay that way for a few days.
I finally did a block test which tests for any sign of exhaust gases since i was getting small air bubbles especially in the morning.
I had to remove the radiator cap and take out a little less than a pint for the test. I had it running for a while this way. No exhaust gases present when Hot or cold or even when it was cold in the morning and I had bubbles coming in to the overflow.
Seems somehow there was still air in the system or even possibly that the dealer introduced air during there testing since after I did my test I added the fluid back filled the radiator then the coolant recovery know the level has dropped about an inch during and shortly after the cool down from the test.
now the cars level is very consistent and the coolant temperature is not fluctuating nearly as much as it was.
It will go up to 205 in the morning as long as its above say 55 and then settle back to around 199 most times.

 

So why is griffis99 still on here?

 

I doubt it was bad coolant. Car only had 20,000 miles. And the only coolant ever used was dex cool. As for having bad head gasket, I doubt it. The car does not use oil or coolant. Has good power and good gas mileage. It get 30 miles per gallon on freeway going 70 to 75. That is true 30 I check manually, don't use the gauge even though it fairly accurate. I have a feeling black stuff was in radiator from factory. Prior owner said car always ran hot, that is untill I had it flushed.

 

The way i understood it..from the factory they drop in a tablet of sealer "just in case" on the way out the door. Machine shop I used to deal with got ahold of this stuff and it really works..watched a volvo diesel box truck that was pissing a steady stream water off the head ( head job by owner, self cleaned and gouged the head in the rear)..run at idle for 30 min with this stuff and it sealed it up dry! You may have gotten an overdose of this stuff by accident ( or they had a problem) and it got all caught up in the system. Normal dose would have no effect. Same color, similar to pepper.