There is a brown sludge under my radiator cap and inside?

Question

There is a brown sludge under my radiator cap and inside, what could this be from? I flushed the radiator recently and it is back?

Answer 1

You have a blown head gasket. Get it replaced imediatly before you ruin the motor. Youll have to flush the cooling system again. If you dont you will be replacing allot of parts. Trust me on this. Dont listen to these morons.

Answer 2

The best results I've achieved in flushing the coolant system involves taking the thermostat out of the car. The install a flush kit which allows you to connect a garden hose to the radiator and a drain from a heater hose. I flush the whole the whole system with fresh water until it runs clear. At that point I pour in some coolant system cleaner which makes a caustic solution. With this in the car, I start the car and let it get as hot as it can get with no thermostat installed. About 15 minutes of running should be fine. The caustic solution will get all the scale and corrosion product of the sides of everything and clean the system really well.

After that, I start the flush with the garden hose again but this time with the engine running. Leaving the engine running will protect it from thermal shock from having the fresh water introduced and the water pump keeps things churning up well. I stop when the drain runs clear.

At this point you can turn off the engine but let the water continue until the engine has cooled a bit. Generally, only a couple of minutes are needed as the water is considerably colder than the engine.

Let the whole system drain... open up the radiator drain, the flush kit drain, take off the garden hose connection to the top of the radiator etc. Get as much water out as you can.

Install a new thermostat making sure the bleeder hole is at the very top. Close all the drains. Somewhere on the engine, you should find a bleeder screw. Most I've seen are near the thermostat housing. Open the bleeder screw.

Mix yourself a batch of fresh antifreeze coolant to a 50/50 ratio. Start filling the radiator with the fresh coolant until the coolant comes out of the bleeder screw hole. That bleeder should be at a high point in the engine and will ensure all the air has been removed. That's also why the bleeder hole in the thermostat must be in the top most position... to let air out as you are filling the system.

You will find the radiator cap and the bleeder screw hole to be at almost the same elevation so once the bleeder hole starts leaking antifreeze the radiator will almost be done filling or done.

tighten the bleeder screw and secure the radiator cap and your system is just about done. Make sure your overflow tank has been cleaned or it could introduce more junk. Fill it with the same antifreeze solution to the min level on the tank and you are done! The overflow tank serves two purposes... one: to collect coolant as it's temperature rises and the coolant expands and two: To provide coolant when the system cools and contracts.

My system has been running clean ever since. Getting the air out certainly helps keep it clean but there is no hope of keeping it clean if you are getting combustion gases into the coolant through a leaking/blown head gasket.

Good luck!

Answer 3

Not enough info, dude. If you are not losing coolant when driving then head gasket damage is unlikely. If you are driving a GM or other vehicle that was originally equipped with the yellow/Dex-cool antifreeze this could be your problem. Dex-cool, in spite of the many benifits claimed by the manufactuers, has a habit of sludging the cooling system when the chemical properties break-down. I experienced this very condion on my 1996 Astro 4.3. Using an off the shelf cooling system flush (twice, making sure I ran the heater long enough to fill the system) I was able to clear the system and replace coolant with the standard 'green' antifreeze/coolant. DON'T PANIC. Replacement of the Dex-cool with green should cause NO problems whatsoever -- just be sure vehicle warranty has expired first or you could face possible denial of covered repairs by dealer. I have spoken with several radiator specialists and they all concur that Dex will cause major sludging conditions if not checked and changed on a regular basis. Hint -- take cap off radiator and fill to rim with water. Start engine and watch water for a (very) short time. Sometimes bubbling will occur if headgasket(s) have ruptured. Try not to scald yourself in the process!

Answer 4

Head gasket!
What kind of car?
I'd go with bill on the Dex cool but if you have had it done recently as in 2 years or less then it could not be the Dex cool.
You have not had any sealer put in the system at any time have you?
If you go to an auto parts store that sells Wix filters, you can get little Ph testing strips to see if you have the correct balance in your cooling system.
One thing you need to know is you need to drain and fill your cooling system every two years. The cooling system creates electrolysis as it flows. This degrades your hoses, gaskets, metals, especially if you have a Bimetal system, (Aluminum heads and Iron block) Your engine is slowly digesting its self via the cooling system.
Maintaining the Ph balance is crucial.
If you have Dex cool in your system GM had a voluntary recall on Dex cool and said you should replace it with the green stuff, not everybody knows, knew of this but it is in effect.
I use Global in my cooling system; it too is a long life coolant and I have it in many types cooling systems and it works well.

Answer 5

It sounds like the water jackets in the engine block have developed sludge. Suggest that the block be flushed as well.

Answer 6

I would suggest a complete system back flush and new coolant.

Answer 7

flush water system very good

Answer 8

cowboybill said what I was thinking (if you do have a dex-cool system)