Cooling system Flush

[Bill B.]

My 65 coupe (327/300) has been about 2 1/2 years with the same coolant in the system. I'm trying to drain the block but the plugs on the engine won't come loose and I'm afraid of doing damage if I use too much force. Would an alternate method of pulling the radiator hose off the water pump and running the engine long enough to open the thermostat and let coolant draing that way be sufficient to get rid of enough old fluid and replenish with new anti freeze? Any suggestions would be appreciated. Thank you in advance.

Bill Bonnichsen #32446

[Duke W.]

Re: Cooling system Flush

Try a six point socket. If they come out, but the flats are bunged up, get new plugs and use pipe dope on the threads. Tighten them to only about 10-12 lb-ft. Often when the plugs are removed nothing comes out due to gunk settling to the bottom. Dig it out with a dental pick or equivalent tool.

If they won't budge. Remove the heater core inlet hose from the inlet manifold nipple. Rig up a garden hose to the nipple (you can buy valves with one threaded and one clamped hose connection at a hardware store) and open the radiator drain valve. Run water slowly through the system until the affluent is colorless and tasteless.

Shut off the water, close the valve and fill the system with water and run the engine until the thermostate opens. Drain and when cool, cold flush it again. When this is done and the system has drained as much as possible, close the radiator drain valve, add two gallons of Dexcool, and top off as required with distilled water.

Duke

[Chuck S.]

Duke, Duke, Duke...

Are you still using that Dexcool stuff? Give it up already. That stuff is liquid doo-doo, Man. I don't even know where you can buy it anymore; I suspect Texaco is the only outlet (their product), and it costs about $15-$20 a gallon compared to about $6-$7 for major brands of ethylene glycol coolant.

GM is up to their waistband is owner lawsuits for damaged engines and cooling systems. I tried it in my wife's Avalon, and over two years, it leaked from the thermostat housing, and from every block plug and hose connection. The trouble was that it was more like seepage or drips rather than leakage, and unless you looked closely, you were unaware you were losing coolant until the car suddenly overheated. I had a tiny little drip stain on my driveway that I thought was an oil pan leak. Further, when it's hot and hits air, it turns into a crusty, slimy mess on the outside. No more Dexcool for me!

[Terry M.]

[Duke W.]

Re: Duke, Duke, Duke...

I still use Dexcool in all my cars (since 1996) including my '88 190E 2.6 and '91 MR2 and have not had any major problems. I still believe Dexcool provides better cooling system protection, especially for aluminum. Yes, GM has had some problems, but they've built about 40 million cars and light trucks with Dexcool, and the frequency of problems is low. The squawking is far in excess or the seriousness of the problem.

I have noticed that Dexcool has more propensity to seep than green stuff - probaby because Dexcool has no salts than precipitate out and plug the leak path. In my case, it was just been a matter of snugging hose connections. When Dexcool leaks it leaves no white residue, which are the salts/silicates in conventional antifreeze. These salts slowly precipitate out in the cooling system and will eventually clog the radiator tubes. This will NOT happen with Dexcool. If the seepage persisted I was going to add a couple of Bar's Leak tablets, which are added at the plant, but I haven't had any seepage lately.

I no longer see the Havoline Extended Life Antifreeze, which is a Dexcool formulation in the parts store, but they carry a Prestone brand Dexcool, and it's eight or nine bucks a gallon.

Another alternative to consider is Zerex G-05. G-05 a "hybrid" with a corrosion inhibitor formulation that is basically organic, but has a small dose of silicates and maybe a small amount of other salts. Dexcool is has a purely organic inhibitor formulation and green stuff has purely inorganic inhibitors - salts including silicates. They plug the minor seepage paths, but also clog up the radiator tubes over time. The G-05 formulation is the coolant used for a long time by Daimler Benz it is now used in all new Daimler Chrysler products. Ford also picked it up in 2002, I believe.

I considered swapping the Merc back to G-05, but I prefer the silicate free formulation of Dexcool. Silicates are abrasive and tougher on the coolant pump seal.

Duke

P.S. Chuck, shame on you for letting your Avalon overheat. Don't you know you're supposed to check the coolant level once in a while. Don't know about the Avalon, but on most cars its just a matter of eyeballing the coolant level in the pressurized expansion tank or coolant recovery tank.

Toyota's antifreeze is also basically an organic formulation, very similar to Dexcool.

[Duke W.]

Re: Chuck, Chuck, Chuck...

Terry -

How do you determine if the antifreeze needs changing? Those litmus strips that test reserve alkalinity on conventional antifreeze (green stuff) aren't applicable to Dexcool.

I've also been changing the Dexcool on all the cars every two years. Being as how that's only a few thousand miles, I've been thinking of extending to three or four years.

Duke

[Chuck S.]

Yeah, Yeah, Yeah...

"Don't you know you're supposed to check the coolant level once in a while."

I know, but years of green stuff in newer, tight vehicles have spoiled me. The fact that coolant leaked out bad enough to overheat took me totally by surprise. I haven't had routine operation lead to overheating since I owned a 400ci 72 Impala. An early effort to solve the overheating problem on that vehicle was retrofitting a coolant recovery tank, but it was to no avail. After limited success at keeping it cool, I executed the final solution and sold it to some other poor schmuck.

Checking the level in that Impala's coolant recovery tank was futile...Fergettabout it...You could drive that thing around the block and the recovery tank would be empty. It was like...permanently empty...an empty way-station on the way to the ground.

Perhaps the fault is not the Dexcool formulation, but only the Havoline coolant version that I used. Locally, Pep Boys, Checker, and other auto parts stores that once sold the Havoline Dexcool don't sell it anymore (Hmmmm...strange). You can only get it at Texaco stations or convenience stores. BTW, you are right, I didn't get any gray salt precipitation...just some orangish crusty residue weeping slime...looked like a hot springs deposit in Yellowstone.

I went down to Toyota and ponied up the dough for their "red stuff"; so far rock steady temp gauge, no leaks, no runs, no overheats. I am glad to know that I am getting the benefits of organic additives, but if you have to walk for water, additives will seem a distant secondary priority.

[Doug Flaten]

Re: Duke, Duke, Duke...

I bought some Prestone a week ago at Autozone, and it was over $9 per gallon. I guess the oil & gas prices are having an effect on these products. Or maybe a plant went down like it did several years ago when glycol prices spiked.

[Lenn #40977]

Re: Duke, Duke, Duke...

What about Royal Purple and Water Wetter?

[Duke W.]

Re: Yeah, Yeah, Yeah...

I use Dexcool in the '91 MR2 - never a leak, but I did have some minor seepage at hose connections on the Merc and Cosworth Vega. The MR2 coolant reservoir is tough to check because it is at the bottom of the engine room. I have to crawl under the back and shine a bright flashlight at it to see the level - keeps me limber and flexible.

Dexcool is Dexcool regardless of the brand. It's the same patented, licensed formulation regardless of brand. Don't know why the auto parts stores don't carry the Havoline Dexcool product anymore - probably has to do with price and shelf space. These stores have so many products, nowadays it gets downright confusing.

Duke

[Duke W.]

Re: Duke, Duke, Duke...

Royal Purple? Don't know what it is.

Water Wetter is pointless, useless, a waste or money, and potentially chemically incompatible with some antifreeze formulations.

The only time to use Water Wetter is if you race you car with an organization that does not allow antifreeze - just straight water. This rule has been adopted by some sanctioning organizations because anti-freeze makes the track slippery if spilled and is tough to cleanup.

For highway vehicles you should run a 50/50 mix of antifreeze (I prefer Dexcool) and distilled water and NOTHING ELSE! Like a proper motor oil, modern ethylene glycol antifreeze products have everthing else you need - corrosion protection, coolant pump seal lubricant, etc, and there is absolutely no need to add supplemental additives to motor oil, antifreeze, or transmission oil. The one exeption to this is the friction modifier additive for conventional 80W-90 GL-5 gear oil that should be added to Positraction axles.

Duke

[Duke W.]

Re: Duke, Duke, Duke...

Ethylene glycol is a synthetic product that is produced from petrochemical feedstocks derived from crude oil, so the increasing price of crude oil is bound to show up in virtually everything including plastics.

Duke

[Chuck S.]

Actually...

"Don't know why the auto parts stores don't carry the Havoline Dexcool product anymore..."

Duke, auto stores here don't carry ANY Dexcool formulations anymore. Before I discovered the weeping fountains (and knew better), and was replacing coolant every week in the summer, I would have been happy to have a worthy substitute. Havoline was the only brand Dexcool they ever sold, and now it's gone.

Ah, it's probably just these backward Texas store managers trying to cover their backsides after reading all the gloom and doom in the trade magazines. But, then that pink, environmentally friendly stuff didn't go over too well here either...not too much green to kill around here anyway.

[Duke W.]

Re: Actually...

My local Pep Boys and Autozone stores carry Dexcool from Prestone - silver jug, orange cap.

Duke

[Terry M.]

Re: Chuck, Chuck, Chuck...

Duke,
I don't test....I change on a calendar basis.

The Gen II units are daily drivers, so the mileage is reasonable to change. On the Corvette I just figure it is the requisite good maintenance.

Although the Gen II cars were green from the factory, the previous owner (state of North Carolina) used Dexcool. I am continuing their practice. Every two years I clean the system with RMI 25 on those cars. Unfortunately the Corvette doesn't get enough use to use that product.

I forgot I have a 3.1 liter V6 with Dexcool in it too. Same previous owner change-over. With the propensity for those deck surfaces to crack I am using Bars Leak in that car. I clean with RMI 25 and flush fluid every two years on that one too.