brians96Z

Ok, I completely flushed out my cooling system today on my 96 Z28. It was pretty corroded, so I figure it still had the factory coolant in it. Anyways....I was told to use the standard *green* antifreeze instead of the recommended DEXCOOL. So, that is what I done. I now have straight green antifreeze in it, now I am kinda worried because I have been doing some reading and found that green can damage aluminum, and cause premature corrosion, and also that I should have mixed it with water. (50/50 mix) What should I do, will it be ok the way it is? Should I just drain some of the coolant out, and add some water? Or should I just start all over again and use DEXCOOL? Also, what temp does everyone else's LT1's run with the stock thermostat? Mine is running 210-220 on the highway. It was running that temp before the coolant flush, and is now too. Please help me out here. Thanks in advance!

Birdman7389

I dont know one way or the other about what KIND of coolant, I'm probably going to stick with what the factory put in it.

You do need to at least drain half of that antifreeze (dont let your cat/dog lick it ) and refill with distilled water....that could be your running a little bit warm problem right there.

teke184

coolant is not designed to be run full strenght. it probably won't cool anywhere close to as well as proper 1:1 mix.

drain half and add water, then bleed the system properly (search).

mebanditws6

Start over and use Dexcool. The water pump seals will wear out real fast with the green stuff. At least that's what my friend's 97 Z he used to have did. ALWAYS use a 50/50 mix. I'm surprised you're not overheating as it is right now with no water mixed in.

Jason

Z28barnett

I would suggest the following.

Get a prestone flush kit at walmarts.

Buy two gallons of prestone Dexcool 5/150,000 undiluted coolant. Buy two gallons of distilled water. If you want some extra buy three of each.

Drain everything out of the radiator.

Drain the overflow tank by putting a hose wrapped with a rag into the top and blowing. The coolant trapped there will flow into the radiator neck and you can drain it at the bottom.

Cut the heater hose below the black plastic flow valve in a handy spot.

Splice in the flush connection.

Connect a garden hose and flush all of the coolant into a bucket for save disposal.

Repeat with the engine running per instuctions.

Let the engine cool and drain the water. Remove the plug near the oil filter and the Knock sensor to drain the block.

In a clean two gallon or larger bucket, mix one jug of water with one jug of prestone.

Buy "Barsleak" pellets and add two to the radiator. Per GM instuctions.

Close all valves air bleeds, replace block screw in drain plug and knock sensor.

Check the refill instuctions in your shop manual, follow them to the letter.

Refill the system.


Half assed approach,

You could still run green, but you can't run it straight. You need to thin it down to 50%. Check with a coolant hydrometer, $3-4.00 at walmarts. Just suck up some fluid with it and see what % it says your mix is. There is pre-mixed antifreeze available that has water added. If you got that you are ok and can stop messing with it.

Pure antifreeze doesn't transfer heat as well as 50 % mix. No advantage to running 100% unless you are in artic conditions.

Best of luck, just did this on my 95 with dex cool, it came with green. I changed hoses also, major pain.

Birdman7389

Ok, so do everything but this. If you have no leaks there is no reason for it, and if you do have leaks, fix them PROPERLY, dont use a band-aid that will make your cars cooling system operate worse. "Stopleak" and its variations will clog up your radiator, and leave deposits in the rest of your cooling system.

brians96Z

Ok, I just completely drained my ratiator, and replaced the straight antifreeze with around a 70 water/30 antifreeze mix. I figured by the time all the rest of the straight antifreeze from the hoses and the heater core, and anywhere else, that it would end up being around a 50/50 mix. The antifreeze I used says on the container that it protects all cooling system metal, including aluminum. So, that makes me feel better, having the LT1 aluminum heads. What is all your guy's LT1's running at highway speeds? Mine stays right at 200-220 degrees at all times. Is this normal?

Bryan Smith

Mine with the stock thermo would run around 190-210. Now with the 160 thermo I never reach the 1/4 mark during highway cruising. Sitting at idle, well stock fan programming forces me to run around the city at 200+

brians96Z

Bryan, do you have any heat in the winter with the 160 thermo? That is my only concern with buying one, because we have some cold winters here in Ohio.

'94 Bad A Z28

Use the green unless you want to waste money.... They didn't start using the orange stuff untill '97.

'94 Bad A Z28

My car with the stock thermo and fan programming would always run at a little below the half way mark, and with my fans reprogrammed my car never gets above the 1/4 mark sitting in traffic, and only about half that when driving.

Bryan Smith

Yup

brians96Z

Thanks Bryan. You probably seen a pretty big power increase right?

Z28barnett

In the 95 and I assume later cars with aluminum / plastic radiators. Gm specifies the use of two addtive pellets. Gm has their own part number, but it is clear if you use them that it is repackaged barsleak.

It helps the water pump seals, and is required by GM when changing the coolant. I have 90k on my orginal radiator and water pump. No clogging or leaks.

Your suggestion about fixing radiators right is good, but in this case wrong.

If you get an actual shop manual and read the coolant procedure you will find that I am right. Add two pellets, no mistake, GM designed it this way.

chrism400

Running hot on the highway is usually caused by a missing air dam. Is your air dam installed?