I have a 2000 civic and I did a radiator flush, but my radiator and the entire cooling system is still covered in a brown goop.

What do I do to get the system entirely clean?

 

And you sure you don't have a blown head gasket??

 

How would I know if I had one?

There's no knocking and it runs fine. Just gets hot.

It might of had one prior to my buying the car.

 

Your head gasket IS blown. Fix that and then replace the radiator and flush the system and heater core until that nasty gunk is gone.

 

My guess is that the previous owner had a blown head gasket replaced without checking the head or resurfacing it.

 

What should I do then?

I dont think the head gasket is still bad.

Do i replace the entire cooling system?

The car gets hot when I'm stopped but thats because of the cooling fan switch which I replaced today. Thats when I realized the brown mess was still in the system.

Its only on the walls of everything inside the cooling system....

 

you want to remove the thermostat first, but use a garden hose and flush the system with water for a bit. run it through the radiator cap and take the bottom drain plug completely out. if it's bad, remove the radiator hoses from the radiator and spray in there to get to the system better. keep your heater core shut for the first few minutes so your not sending more crap in there. just hope there not too big of a mess in there or you probably will have to replace some stuff if it runs hot again.

 

Let the car run for a few seconds then check your dip stick. If your dipstick has this gunk you talk about then your head gasket is ruined. If not, then follow brick_top's advice.

 

Use CLR it cleans the cooling system Very Well.

Warning CLR Will remove any stop leak or heavy oxide's that may be pluging any pin hole leaks

 

you say brown gunk? i'd say that some one was running mineral rich water in your cooling system with hardly any antifreeze (BIG NO NO!!!!!!). blown headgasket goop is a light brown like a mocha or tanish color.

pix?

 

I'll upload some pictures as soon as I can.

By dipstick do you mean the oil dipstick? That has never had any of the brown mess on it.
So I think my head gasket is fine.

I'll try the water thing and if that doesnt work, the clr thing.

But I'm gonna post pictures first to make sure thats the problem.

 

Well I never got around to taking pictures, but I figured out that the car had previously had a blown head gasket AND the guy was running hose water ONLY for fluid.

What can I put in the radiator to completely clean the walls of the entire cooling system?

 

Someone told me to put drain cleaner in, another said degreaser, another said white vinegar. Wont those damage the system?

 

they already told you how to do it. a hose, maybe some clr, and if all else fails replace it all.

 

what is clr?