boonie

While in the process of replacing both my thermostat + leaking radiator i notice that my coolant came out muddy brown instead of green, what can i do to remove the remaining dirty coolant without having to remove the anti knock sensor so that i can put fresh coolant in that won't get contaminated with the old coolant?
your opinions will be very appreciated.
thanks boonie

engle1147

Sounds like it has already been contaminated if you have brown sludge. I'd drain and flush the entire system with water and then refill with whatever your new coolant choice might be.

Pwnage1337

You beat me to it.

383vett

It will be better if you drain out the whole system by taking out the knock sensor and plug on the driver's side. Refill, get it up to operating temperature, drain again and fill with distilled water and antifreeze. The brown stuff is either rust or someone mixed orange with green.

PLRX

Here is a picture on "how-to-do-it"



Take one knock sensor to home depot, buy 2 male fittings a T connector and plastic hose. You will see lots of junk coming down and you'll be glad you took the KS out.

383vett

What's that magnetic doohicky on your oil pan? You've got the cleanest pan and clearest coolant I have ever seen.

1989vette

It looks like a magnet holding a work light. To me atleast.

theadmiral94

One other school of thought is that by using a shop vac and after draining the radiator, blowing into the black surge (pressure) tank, it will push out the rest of the 'junk' and bad coolant.

You will likely have to do this a few times -- and depending on what type of water you have at home (i.e. well or high mineral content), you can instead use distilled water (12+ gallons) to add/run/drain/blow-out/add/run/drain/blow-out.... till clear..... remove/replace thermostat.... add pure anti-freeze (1/2 system capacity), top off with ONLY distilled-water... run... top-off and cap-off within 2 minutes -- cycle rpm 3k to idle in 30 second intervals, watch temps... lastly don't drive hard until 3 full warm-up/cool down cycles (so that water/anti-freeze is completely mixed). Don't forget to clean/flush the overflow bottle (by the bumper).

garychurchill

when I did my 86, i replaced the thermo (as everyone would), while I was at it I blasted the system out with a hose right from the thermo until I was getting clear water out from one of the bottom hoses. Then I let it all drain out, reconnect and then on with the rad fluid.

flynn508

Dont forget to address the reason that your coolant is brown sludge to begin with; put a new radiator cap on !!! I had this issue with another Chevy. The bad cap allows air into the radiator, which somehow accelerates corrosion inside the radiator. Mine was filled with so much sludge that my mechanic flushed it about 5 times and was still getting buckets of crap out, so we just put in a new radiator. He said that it is a common Chevy issue with crappy caps, and the type of coolant.

tim32920

How about take the thermostat out, drain it and refill with clean water and some TIDE. Let that run through the system than drain it than rinse it than refill with coolant. Worked for mine when I replaced my radiator.

GREGGPENN

Isn't brown coolant also an possible indication of a failing intake gasket? Though it might not be significantly compromised at this point, I'm thinking small amounts of oil crossing a gasket could result in a color change.

Several yrs ago, when I first checked mine, there was a glop of brown sludge sitting under the cap. Wasn't sure it was rust either.

This incident -- combined with the reputation of the SBC intake gasket -- led me to feel compelled to swap intake gaskets...then intakes...then headers....then heads.... LOL!!!

TravisD

The brown sludge is probably from the clay-based "sealant" tabs that GM likes to use.

You might consider going with plain water and Redline water-wetter for the summer -- use your normal drive-time to thoroughly flush the system. The Water-wetter will provide the necessary lubrication and anti-corrosion. Flush/fill a couple of times after putting some miles on it, then before winter switch back to a 50-50 antifreeze mix.

383vett

Water wetter is good stuff. I've been using it for years. OP lives in Sacramento. Mild winters, no snow. He'll be fine going w/o antifreeze. I always run about 10-20% antifreeze just because...

dreamer2468

Laura

engle1147

water wetter is great stuff. Running a % of antifreeze also keeps the internal rust level down.

pcolt94

Man that engine is clean. Guess they have clean streets in California, kinda like Pleasantville.

94ZR1

I would also recommend that the coolant be changed more than once every 10-15 years

frenchyoliver

You should first consider running high flow water in the radiator, reverse way to allow all the rust to come out. Then the KS technic.

Never ever use water in a coolant system. If you have an air leack it will be back brown within 1 day.

Use only full synthetic glycol based coolant. No rust, stay clean, stay cool.

flynn508