brown shit in coolant tank

[TaterWagon]

Got a "low coolant level" display last night. Checked the tank and it was nearly empty except for the muddy brown stuff in the bottom. I have 38k miles on the truck, and I'm going to go ahead and change the coolant. Question 1: Is that brown stuff going to be throughout the system, or does it float on top like in a septic tank? Question 2: If it is throughout the system, can it be flushed out? Question 3: I will go ahead and replace the t-stats while I'm at it; should I get them from the dealer, or will aftermarket be OK?

If this has already been covered, point me in the right direction because I didn't see it in my earlier search. Thanks!

[Tom S.]

Flush your system. If you have it in your reservoir, you have it in your system, most notably the heater core.

The leading cause of this is a improperly sealing radiator cap and/or reservoir cap. As for the thermostats, if they aren't broke, why 'fix' them? I'd leave them alone.

[TaterWagon]

Thanks for the response, Tom. Is that sludge difficult to flush out? I replaced my expansion tank cap a few months ago due to the upper radiator hose collapsing when cold. That took care of that issue.

Regarding the thermostats, I just figured it would be a good idea to change them with the Dex. If it isn't necessary, I won't mess with them.

Any further insight will be appreciated. Thanks.

[ST04]

refill with coolant that is made with distilled water. Sometimes tap water can leave deposites and corrode out your radiator.

[Tom S.]

I don't know on the D-max because I've not done one yet. On my S10, I used the Prestone stuff to flush the system, and then disconnected my heater hoses and used a garden hose to flush it both ways - forward and back. There was a lot of that 'stuff' in it.

As mentioned, use distilled water to get your 50-50 mix, or buy the ready mixed stuff.

[Mike Miller]

Firstly what is the base of this brown stuff ? Is it oil base or what? If it is oil base you have a larger problem because oil is entering the cooling system

[srjacob]

What is wrong with replacing the T-stats at the same time. It is just a matter of time when they go bad.

Just a question? If you you use distilled water or mineral free water, wouldn't the lack of minerals in the water pull minerals out of the cooling system it self?

[Tom S.]

Originally Posted by srjacob

What is wrong with replacing the T-stats at the same time. It is just a matter of time when they go bad.

Just a question? If you you use distilled water or mineral free water, wouldn't the lack of minerals in the water pull minerals out of the cooling system it self?

I have sold vehicles with close to 200,000 miles on them that still had the original thermostat. Why do you say it's just a matter of time before they go bad? In fact, on three vehicles I've had, the thermostats out lived the radiators. So using your logic, I guess he should replace the radiator too?

The idea of using distilled water, which goes back many many years is to keep people from using water with minerals in it that are harmful to the cooling system. You might be surprised what minerals can be found in our drinking water. As a friend of mine used to say "never drink water because fish pee in it". Of course this was only his excuse for drinking beer.

Also, additives in the antifreeze help keep corrosion from forming in the cooling system, and adding tap water can neutralize these additives.

[TaterWagon]

Thanks, guys. I already planned on using either distilled water or the premixed stuff. My water has a pretty high mineral content, and I don't want it in my cooling system.

Tom, is that brown stuff difficult to flush out? What is it, degraded Dexcool or something else?

Thanks.

[Tom S.]

Originally Posted by TaterWagon

Thanks, guys. I already planned on using either distilled water or the premixed stuff. My water has a pretty high mineral content, and I don't want it in my cooling system.

Tom, is that brown stuff difficult to flush out? What is it, degraded Dexcool or something else?

Thanks.

I don't know exactly what it is - I was told it's caused by dirt getting into the system, but I suspect it's not just the dirt, but possibly something in the antifreeze reacting to the dirt.

Anyway, the Prestone seemed to work for me - but I did do two flushes to make sure. That was four years ago, and the truck is still good, but time wise, I probably should change it again.