Coolant Overflow keeps getting dirty

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Last month my coolant overflow tank was dirty with brown stuff and i flushed it really clean now its starting to look dirty again but not really with browing why can this be? My oil is always full and so are my other fluids?

19995 BUICK CENTURY 3.1 V6
 
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There's a bunch of sludge and grime deep in your engine block that slowly floats to the surface and finds its way to your bottle.

A good system flush will get a bunch of it. If you have an iron block though it'll be shedding little rust flakes for a while.

If your coolant chemistry got off sometime in the car's life its corrosion inhibitors could have worn out causing the rust to start. Not a huge deal. Could even have casting sand if it's never been changed.
 
What type of vehicle? Is it one that is known for cooling system corrosion?

Depending on the cooling system type (open/closed), when the engine gets hot, it is going to have excess coolant go into the tank. Then, when the engine cools down, vacuum is going to suck it back into the engine.

If there's a corroded cooling system with junk floating around in it, it's going to come out with the coolant from the radiator and be dumped in the bottle. Since it's a bit heavier than the water, the vacuum that draws it back into the radiator isn't going to suck it out of the tank.

You have a corroded cooling system. Do a flush and look at all the of the cruddy coolant that comes out.
 
That i dont know i was gonna get a flush but was worried when i heard a flush done by those shops will only make things worse?
 
It can only make things better. Do the flush asap because old coolant loses it's ability to resist freezing. Some cold nights are coming soon!
 
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How long have you had the car? Something with such low mileage probably has the original coolant. I bet there isn't much left of the water pump impeller and the heater core.
 
but is it ok to do the flush when the car is hot since i will be driving it into the shop and they will do it for me?
 
Originally Posted By: boostedtsiawd

19995 BUICK CENTURY 3.1 V6


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Originally Posted By: Miller88
How long have you had the car? Something with such low mileage probably has the original coolant. I bet there isn't much left of the water pump impeller and the heater core.


+1.

I switched out the coolant on the infamous Volvo. We also strongly suspect original coolant.. well, mixed indicators, actually, but still, it looked brown, and like a toilet. I changed out the coolant, and the coolant looks more the original color now, less brown.

Will clean it again, as well.

If you can do it properly, the water run through the radiator will be dirty for MINUTES, if you have the chance to flush the system in this manner.
 
Originally Posted By: boostedtsiawd
That i dont know i was gonna get a flush but was worried when i heard a flush done by those shops will only make things worse?


You are probably refering to transmission flushes which sometimes make the transmission worse because the flushing procedure knocks loose varnish and grime that doesnt always get flushed out and makes the valves in the transmission stick etc. A radiator/coolant flush is always a good idea.
 
Originally Posted By: boostedtsiawd
Do i have to drain the engine block to when changing the coolant or its fine to do the flush without?


There are a few ways... Some maybe sound "better" to some.

The "OFFICIAL" way:

1. Remove the radiator "drain petcock." It is a bolt..
2. Fill up with water, and flushing solution.
3. Let it run through for either 20-30 minutes, or, weather permitting, drive around with it like that for a day or so. *You can only see what comes out of the radiator, but this "flushes the block," as you say. Yes, that is important.. it is all in the method, as the coolant circulates through the block, ..like I said, there are a few methods to achieve the same result. Some may be more "thorough." To me, it is all about when the drained water looks clear.
4. Repeat, until water runs clear.
5. Refill, 50/50.

Now.. an alternate, something we Shadetrees would do.. Got access to a garden hose?

1. Remove the LOWER hose, from where it attaches to the BLOCK/water pump.
2. Take off the UPPER hose, at the other end.
3. Let the garden hose run THROUGH the radiator. (On a car I had, the water was dirty for a few MINUTES before it ran through clear, and not brownish-dirty.)
4. Now.. Is the engine COLD? If so.. Remove the Thermostat, and let that garden hose flush through the engine, coming out the OTHER side of the lower hose, going in through the other side of the upper. Same way, with the dirty. (Some may not approve of that, but you are flushing the "block" that way...")
5. Maybe refill with water/flushing solution.. maybe not..
6. Drain, refill 50/50.

Posters are correct, no harm will come from flushing a COOLING system! It is some applications of an (automatic) transmission "flush" that CAN, and have in more instances than some would care to admit, bongle an otherwise working AT into either 1. Not working right, or 2. No Pull.

I am also not familiar with how to use a flushing "T," and I have never flushed a cooling system by using the drain petcock. Always took hoses off, and left the petcock alone.
 
GT is the LAST person to be giving advice on how to properly maintain a car. The only way the OP is going to have an uncontaminated cooling system is to take his car to a shop that can do a complete flush using a machine. Otherwise, there is always going to be [censored] lurking in the heater core and block. I'd recommend they flush with water until it's running clear and then start the 50/50 coolant mix to refill.
 
Originally Posted By: G-MAN
GT is the LAST person to be giving advice on how to properly maintain a car. The only way the OP is going to have an uncontaminated cooling system is to take his car to a shop that can do a complete flush using a machine. Otherwise, there is always going to be [censored] lurking in the heater core and block. I'd recommend they flush with water until it's running clear and then start the 50/50 coolant mix to refill.


That is more or less what I recommended. Any funny pictures to accompany your advice, that was the same as mine? Quit thinking I haven't flushed cooling systems, some kind of way.
 
Originally Posted By: GearheadTool
Originally Posted By: G-MAN
GT is the LAST person to be giving advice on how to properly maintain a car. The only way the OP is going to have an uncontaminated cooling system is to take his car to a shop that can do a complete flush using a machine. Otherwise, there is always going to be [censored] lurking in the heater core and block. I'd recommend they flush with water until it's running clear and then start the 50/50 coolant mix to refill.


That is more or less what I recommended. Any funny pictures to accompany your advice, that was the same as mine? Quit thinking I haven't flushed cooling systems, some kind of way.


Originally Posted By: GearheadTool
Now.. an alternate, something we Shadetrees would do.. Got access to a garden hose?


I rest my case.
 
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