Chevy & GMC Vans

I have run it (Dexcool) in our 2000 Astro 2wd since new.
Only recently did I decide to do a flush after I found what appeared to an almost gelatinous substance hanging from my radiator cap when I removed it after seeing some coolant on the garage floor. This leak was intermittent and only after sitting in the garage and appeared only after the engine had cooled down and had been sitting in the garage say overnight. The leak only began after my wife was using the van for short trips rather than when I used it for to a from work when it would always reach 'normal' operating temperature.
I had used Rislone (Barsleak in Canada) with the small particles to stop small leaks in the past with good success and it has been in the system for quite some time guesstimating more than a year.
I called the Rislone help line and they suggested that I do a complete flush of the system as per this link: http://www.ehow.com/video_2328126_insta ... h-kit.html
I see that a lot of people don't agree with this method.
I actually ended up doing the flushing using the Prestone Super Cleaner: http://www.prestone.com/products/coolin ... tments.php i.e. just drain, treat, drain, flush, drain, fill rather than tapping into the heater inlet hose per the link above.
After using the cleaner, the leak appears to have stopped, at least for now, and I am now just running with the water. That is not quite true. I am a little worried that I might have a small leak in the engine oil cooler portion of the radiator so I have put in some Barsleak again. I say 'might' because I see what might be a very small amount of oil in the water in the radiator and the overflow container but there is no water in either the motor oil(as seen on the dip stick) nor in the tranny fluid. What is a mystery is that it doesn't really appear to be engine oil because it is not dark/dirty like motor oil would be.
I have purchased a couple containers of Dexcool from Canadian Tire but was not going to put it into the van until I am sure that I have solved any small leak(s). No use to waste money on Dexcool if I need a new rad and would just throw away the coolant....
I have not heard of this beef about Dexcool before. I see the GM service bulletin refers to vehicles which have had the coolant level drop too low i.e. not a general problem...
If you don't use Dexcool, what antifreeze do you use and why?

The problem with dexcool originally was that ( if memory serves me right ) was that when air was introduced to the system it would re-act with the dexcool and then start eating away at the intake gaskets, once this happened it was only a matter of time before the coolant got into the engine oil ( i'm assuming by dripping into the lifter valley, but i could be wrong ) and caused big time problems.

I use standard ethylene glycol in a 70/30 mix (it gets COLD here in Montana). Prestone or Peak seems to work just peachy. My experience with Dexcool is not good (Freightliner). Of course, that could be coupled with that lame engine, the Caterpillar C12.

astrozam wrote:The problem with dexcool originally was that ( if memory serves me right ) was that when air was introduced to the system it would re-act with the dexcool and then start eating away at the intake gaskets, once this happened it was only a matter of time before the coolant got into the engine oil ( i'm assuming by dripping into the lifter valley, but i could be wrong ) and caused big time problems.

pretty much it right there. It also likes to break down into some serious cooling system clogging gunk. I flushed the dexcool out of mine and was amazed at the amount of brown crap that came out of the block.

Also the intake gasket problem was exasperated by the filler neck on the rad having a rough surface causing the cap to stick and not work properly, allowing alot of air to exchange into the system by coolant draining out into the overflow container even when the coolant wasn't hot enough to need this. There was a TSB regarding this way back. The solution was .................. Sandpaper lol.

I'd park it and walk before I ran Dexcool.

I like the regular green stuff, but end up running the "Mixes with all" type since you can't ever really totally flush all of the old out. It isn't a good idea to mix the different types.

The 'Super Flush' won't touch the Dexcool sludge. Look here: viewtopic.php?f=6&t=5199
for the proper way to flush it out. Even after this, and with the coolant looking good, I found this:






and when I pulled my radiator for replacement, it weighs 2-3 times what the new one does. I started with just a little rust colored sludge on the radiator cap.

Once the dexcool starts this process, I don't know if it can ever really be stopped. I flushed it every 6 months for 4 years with the same "Super Flush" with no sucess, the sludge came back each time, and I went through 3 water pumps (I love lifetime warranty), and on the third pump I did the acid flush, then the intake gaskets, and then the bottom end failed in the engine, prolly due to antifreeze getting into the lifter valley. ](*,)

Bars leak, etc, is a bad idea in my opinion, plugs your heater, radiator, other small passages, etc. Find the leak and fix it, you'll be glad you did. My money is on your intake gaskets being the leak, or the weep hole in the pump.