About eight months ago, prior to reading all the scary negative stuff about the horrors of DexCool, I flushed the cooling system on my '87 5.7 and put in DexCool.

Right away, I noticed the engine ran about 10-degrees cooler than with the green stuff. Since then I've had no problems, but have noticed the overflow tank now has a brown stain, apparently caused by DexCool exposure to air.

Is it possible to convert the vented cooling system on 3rd Gens to a closed system more compatible with cooling solutions requiring such an environment?

 

Theres really no such thing as a non vented system. The coolant needs somewhere to go when it gets hot and expands. There are systems that have a pressurized overflow instead of a non pressurized one but they still contain air so that wouldnt aleaviate your problem with air in the system.

 

When I was following the DexCool threads, mention was made of "non-vented" cooling systems in which outside air was excluded. Apparently, these types of cooling systems were developed around 1996. Unfortunately, since my cars are all older, I have no idea how the new cooling systems work.

If they cool better, it would be of value to our ThirdGens, which tend to overheat easily.

Anyone have experience with this technology?

 

The best coolant that you can use is a 100% mix of water with an additive that will both lubricate and prevent rust. Seeing you live in hawii it may be a viable option to run that all year round.

 

I think you could convert that system to non vent fairly easy, you need to first remove the pressure spring and large washer with the rubber seal on it on your radiator cap, now all of the air/coolant mix can route to a sealed tank though the overflow tube that is there now. that tank can be had off just about any late model gm product...most even have a coolant sensor for low conditions which could be utilized too. Early dex cool systems did poor in many respects, non vented systems seem to have "fixed" most problems that the stuff creates...corrosion is still a problem, seeps form crusty deposits, Most cooling systems are really in poor shape when that magical 100,000 miles finally rolls around..I know I deal with them every day I change an intake gasket on a gm product at least twice a week...personally I wouldn`t touch the stuff with a ten foot pole..I did try it for a while and it started leaving stains on anything it touched..really no reason to use it IMO. Nearly all of the manufactures have got away from it too.

 

Thanks for the input ... well, I don't want to be the first to mod my cooling system into a sealed configuration and possibly screw it up, heh. I wonder if any of the 30,000 members here have changed to a sealed cooling system ... anyone?

On the topic of DexCool -- whether it's the evil acid or not, I was under the understanding that it has been installed in just about all new vehicles since 1996. If this isn't true, what coolent are manufactures shipping new vehicles with?

Another question would be: why are some people having DexCool problems and other's aren't?

 

What additive would you suggest?

There's no freezing conditions here, but an additive with those qualities AND increased thermal transfer would be most welcome in this tropical environment!

 

Cooling Thirdgens is a major problem and nobody here has converted the stock open cooling system to a closed, non-vented one?

Please, anyone that has done this mod, would appreciate knowing if it's worthwhile or not...

 

I have a done a bunch of online reading on Dex Cool and there is no definite answer. Some people have had no trouble while others have horror stories.