I have an 87 that I have had for 2 years and recently the low coolant light has come on so I decided to do a flush.
I could not find the petcock so I removed the lower and upper hoses and the overflow reservoir. Yesterday when I drained I was surprised to see orange fluid. I thought from everything I read you should be using green Ethylene Glycol based? I googled 87 C4 Corvette antifreeze and I'm getting Prestone Dex-Cool antifreeze Orange GM Vehicles listed on the AutoZone site. It says we have "15 coolants for your 1987 Corvette Engine Coolant and Antifreeze" and the Prestone Orange Dex-Cool is also listed. (Please see link). I went to the store and on the back of the bottle, it says GM Vehicles 1995 and above. So now I'm really confused. https://shop.advanceautoparts.com/fi...tifreeze.c6301
1. What coolant should I use?
2. Can I even go back to green if the previous owner had orange?
3. Can I use this Prestone Dex-Cool product in my 87?
4. Also I've read that is you're doing a flush you should not buy the premix and buy the concentrate and mix it yourself?
5. Where exactly is the air bleed screw?
6. Any Expertise help here LOL

Also I currently have the system filled with distilled water but the "Low Coolant" light is on, as far as I know, the system is full why would that light be on?


Thank you
Update: I found the petcock I knew whatever I read about 87's not having one had to be bullshit.

 

One thing I’d suggest is to mix your coolant, if not already premixed, with distilled water. There are no minerals in it that promote rust.

 

Yes, thank you I already have gallon jugs of distilled water. Thanks for the help.

 

The Green is had to find in a lot of stores anymore. I just did my flush last month on my 93. It also called for the Green. You can get it at NAPA, their brand is about 12/gal and Prestone is 16/gal. I'm sure it the same stuff as there are only 3 manufacturers that make anti-freeze. To drain your block you need to remove your knock sensors, one on each side, and then flush.

 

Orange can just be nasty/rusty coolant too… just flush it really well, including the heater core and fill with fluid of choosing.

 

I would not use Dex-Cool in a pre 96 car.. GM went to Dex-Cool in 1996 and used the green from day one to 1995. If you had Dex-Cool it must be completely flushed out. You can't mix the Dex -Cool and green. But as another poster stated, if your coolant is very old, it could just appear orange due to some rust.

 

Nixonplumber - OK - First off - it's in your best interest to do a thorough flush of the cooling system. That involves pulling the two block drain plugs (which sometimes have knock sensors threaded into them), and disconnecting the heater core hoses, and flushing the heater core out with a garden hose.

Once you get as much of the old coolant out as humanly possible - you flush with water till you see no trace of color in what's draining out.... Then drain out everything you can, reconnect hoses - reinstall block drains and fill with two gallons of coolant concentrate and approx. 2 gallons of distilled water.

There are a number of coolants out there - and they all have their pros / cons. Rule 1 - Color is pretty much irrelevant. There are different coolants that are green, and there are different coolants that are red - so DO NOT trust color alone !

To me - it makes NO SENSE to not run a long life coolant. The fact is that while the ethylene glycol will never lose it's ability to keep the freezing point down - there are corrosion inhibitors in the coolant, and to make a long story short - think of them as sacrificial, so plan on them eventually "wearing out". The corrosion inhibitors in the long life coolants last longer, and do a good job - so why not use them... There are some people that absolutely hate Dex-Cool and there are others that don't. As far as I'm concerned - most of the real negatives about Dex-Cool involve it being mixed with the older Silicate based "green" coolants. If you have thoroughly flushed out your cooling system - it really doesn't matter what type of New coolant you choose to use. I'd either go with Dex Cool or the HOAT Coolants, but that's me. Just make a note of what coolant you used and mark the overflow tank so in a couple of years - you don't have to trust your memory.

 

Nixonplumber, IMO flushing the system isn't needed unless an overheating condition exists. This is what works for my 89. I drain the radiator and refill it every 6 months with new coolant. While not a complete replacement of coolant it still has the ability to keep it's intended properties at a high level. The last thing you want is to tackle the job of replacing the heater core if it corrodes through.

 

I agree with what others say about NOT mixing Dex cool orange with green. It will cause sludge in the cooling system and clog things up. A thorough flush is needed if you change to green. Or just keep using Dex cool. Dex works just fine and got it's bad name from people mixing it with green and dealing with a negative chemical reaction in the cooling system. It's hard to tell if it is actually Dex cool and not some other random coolant though. So to be safe a flush would be safer. Dex was designed to be more compatible with engines using multiple metals like aluminum heads and cast iron blocks. So it's just fine to use in an 87.

 

Ok that you for the detailed advice. This afternoon I flushed the heater core with the garden hose. Now I know you're not supposed to have non distilled water in your system so do I need to get that water out of the heater core once flushed? I have a hand pump but that is not working. Now I need to find the knock sensors which I will probably do tomorrow. I plan on using the dex cool once I fill it. Thanks again.

Update:

Never mind I hooked a funnel up to my clear hoses and poured a gallon of distilled water in and flushed the garden hose water into a tray.

 

Cool !!!! The block drains are about half of the way down each side of the block - maybe 1" above the oil pan. (needless to say - you get to them from underneath the car). I believe it's a 1/4" NPT thread. IF you unscrew one, and nothing comes out - it's likely that there is so much "crud" in there that it's blocking anything from flowing out, If that happens - try "gently" tapping through the crud with a small dia. punch or drill bit - or try pushing some 12 ga. solid wire into the threaded hole in the block.

It's going to be messy - so expect to get old coolant all over (including on you), But - many of us have seen some real "crap" come out of the block drains. On my used 92 - when I first did the full cooling system drain - some of the liquid that came out from the block drains was black !!!

While doing the full cooling system flush is a PITA, you will feel pretty good about reassembling with fresh coolant. You'll know the system is as clean as it can reasonably be. Now - you can probably just do radiator drain and refills every 2 - 3 years.


GOOD LUCK !!!

 

Hey, I flushed everything and I'm leaking coolant between the radiator and engine above the belt. I'm now running pretty hot around 230 before I shut it off and I have a hissing sound. Is this a bad water pump? I attached a video with audio of the hissing.
ve

 

OK - when you did the system refill, did you open the little brass air bleed by the thermostat ?? If so - that might be leaking. Did you pull either the upper or lower radiator hoses off ??? Again - they might be leaking. Try to identify the leak by feeling around with a paper towel, and see when it gets wet.

I would not bet that the water pump went bad all of a sudden, sure it's possible, but I'd suspect a leak at one of the cooling system connections first.

So - what did the coolant that came out look like when you opened the block drains ???