I have had this ever since I bought the car. My coolant in the resovoir with the dipstick is black and looks almost like oil. It has a little bit of a burnt smell to it. I was thinking it might be a stop leak though... My actual coolant when I open the radiator cap is a perfect I plan on green antifreeze. It looks just like it should. Im putting a 160* stat and a tb bypass all in one day. I am really worried about leaking on the opti and on shoebox's site it says it is safe to drain some coolant. My question is when I drain, say a gallon, from the radiator, will the black stuff in the resvoir dump into my good green coolant?

 

A basic question.... why not just clean the crap out of the reservoir and avoid the possibility of any of it getting into the radiator?

To change the t'stat, its a good idea to drain the radiator enough to get the coolant level below the t'stat. When you put it back together, put the coolant you dranied out of the radiator back into the radiator. Let it heat up, do the air bleed procedure, and continue to add what you drained out. There's no reason the radiator will pull any significant amount of coolant out of the reservoir unless the radiator is not filled correctly.

But since its normal for the radiator to spit a little coolant into the reservoir as it heats up, and then pull a little back into the radiator as it cools down, just clean the gunk out of the reservoir.

 

Heres a dumb question for ya. How do you clean that gunk out of the resvoir? Also I am scared that if it a stop leak (I really dont know what it is) that the car will develop leaks...

 

Can't tell you what you should do.... I personally wouldn't rely on a reservoir full of (maybe) stop-leak to keep my cooling system intact.

 

I have some gunk in my reservoir tank also. Could it be that the coolant is slowly eating away at the plastic tank, causeing this stuff, or does this just happen after 10+ years of use, cause im pretty sure my coolant is the original stuff. I plan on flushing everything out in a couple of weeks.

 

If it's black, there's a good chance it's Bars-Leak, which is actually pretty good stuff and even contains lube for your water pump. It was common for many years to put it into your system as a prophylactic; but that's kind of fallen by the wayside as systems became both more closed off and more reliable.


To get the gunk out, you can either siphon the water/gunk mixture out, or remove the overflow tank completely and drain it like that. If you go that route, you might want to consider a new tank. Not because you need one, but because a brand new tank does a lot for the engine compartment's looks.

 

But its not even visible from above, other than th cap????

(Courtesy of Shoebox)