I have recently acquired a 87 C20 with a TBI350. Giving it the first once over I discovered that the coolant looked like it was river water. All red sediment. The bucket I drained the coolant into needed to have the bottom hosed out.
So far I have given it the initial drain, fill with water, brought to temp, drained again. Filled again with 'Prestone Super Flush', driven for a week, drained (looked the same as the first time), filled brought to temp drained again. It is still the same. I need to add coolant to it soon as I have to head up the mountain to work.
Is there anything to do about this? Just keep running it and change it often? Forget about it?
In reply to former520:
Good chance it is old anti freeze. It turns into a muddy looking sediment when it isnt changed periodicly
If you're worried about deposits I've heard about using white vinegar to clean the cooling system.
I haven't tried it yet but here's what I found online..
In The Car
1
Drain the car's entire cooling system. If you have antifreeze in it, dispose of the fluid properly. Refill the radiator about half way full. Pour in a gallon of white distilled vinegar. Fill the radiator the rest of the way up.
2
Close the system with the radiator cap. Start the car and let it run until the engine reaches it's normal temperature. Shut the car engine off. Let the car sit for several hours or overnight.
3
Drain the water system by removing the bottom hose or by opening the drain valve on the car's radiator. Flush the radiator out with a water hose as it drains. The vinegar is environmentally safe so you don't have to be too cautious, but you might want to catch the deposits and build up of minerals and lime that will be flowing out.
had to deal with this in my truck this summer- 87 GMC body on 79 Chevy 3/4 ton 4X4 chassis with a 307 from a 71 Nova in it, as if any of that matters here..
anyways, i went all out and removed the radiator from the truck and used the hot water faucet in my basement to back flush it with hot water.. then i ran the hose out to the driveway and ran it thru the engine thru the thermostat housing.. it never came out clean, so i removed the drain plugs on each side of the block down by the oil pan and dug out all the crap out of the bottom of the block that i could get to and began flushing it with the hose again. i couldn't believe how much orange/brown chunky crap came out. after about 1/2 hour of that, i put the drain plugs back in, reinstalled the radiator, and filled it up with straight water with some Prestone radiator flush for a couple of days. then i drained it by pulling the drain plugs, flushed a few more gallons of hot water thru it, and refilled it with the customary 50/50 antifreeze mix. it looks kinda cruddy again, so i might have to go thru the whole procedure again.
I've seen this a few times. Best thing to do to start with: remove the radiator hoses and take the thermostat out. Now stick a garden hose in the t-stat hole and turn it on full blast. You should see all kinds of nasty crap come out. Then stick the hose in the water pump opening and do it again. Repeat a few times, alternating top to bottom. If you see removeable plugs like nova derrik mentions, do that as well. You might even consider removing a few freeze plugs, flushing through the resulting opening and then putting in new plugs.
Then do the same thing to the radiator, reassemble with straight water and flush chemical and drive a couple hundred miles, flush again with straight water and then add 50/50 antifreeze.
Don't forget to flush the heater core while doing all this. I have seen them so clogged with rust there was no heat.
I'm working on this same issue with my Jeep. It would be easier to clear up if I drove it.
I have been doing back flushes and it's been helping out a ton. It's still not perfect, but internet research has led me to believe that after you have it as clean as you can get it, you have to keep an eye on the coolant until it's all nicely flushed and you have a decent layer of protection built up.
Last POS i had that was this bad i used a bottle of CLR in it and ran it a week or so. Be careful as CLR is a nasty acid be sure to chase it with a box of baking soda and hot water twice before filling with anti-frezze.
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Also be preped for casting plugs to fail after cleaning
