Flushing the cooling system frequency?

[V10SpeedLuvr]

I had a BG coolant service done on my Viper last December. My headgaskets were replaced BEFORE the MLS headgaskets came out, so I have "new" paper style gaskets. I've been told to do the flush every year by some people and every 2 years by others. I'm going to get all my fluids changed soon and would like to do this at the same time if I need too. So, whats the verdict? Do I need to have it done again this year or can I wait until next year?

 

[slaughterj]

I don't know about these gaskets you have, but according the 98 service manual, you change the coolant after 3 years the first time, then every two years.

 

[ROGUE]

Depends on what you're using as "coolant" but generally no once a year is overkill. Especially if you don't live in an overly cold climate.

Personally I run nothing but distilled (bottled) water and 2 bottles of water wetter. It is much more effective at cooling the motor since I have no need for the anti-freezing properties.

 

[V10SpeedLuvr]

Depends on what you're using as "coolant" but generally no once a year is overkill. Especially if you don't live in an overly cold climate.

Personally I run nothing but distilled (bottled) water and 2 bottles of water wetter. It is much more effective at cooling the motor since I have no need for the anti-freezing properties.

GA isnt an overly cold climate, but today could freeze an eskimo (31* degrees, windchill of 23*) I have the Mopar coolant in mine since it was changed at a Dodge dealership last year

 

[Tom F&L GoR]

The reason for 2-3 year flush recommendations has nothing to do with the gaskets. The traditional green antifreeze uses silicate additives that coat the metal surfaces, but in time, detach and float as jelly-like clouds in the coolant. Therefore you lose the corrosion protection and the concentrated silicates are abrasive and wear the ceramic water pump seals, causing leaks.

Flush treatments therefore remove the old fluid, hopefully rinse hard enough to loosen anything that has settled, and should have a chemical to help remove what it can from the metal surface. When you add new antifreeze, you start all over again.

Newer antifreeze, variously called extended life, long life, DEX-COOL, or 5year/150,000 mile performance, is low or no silicate. These additives stay in solution until corrosion may begin, then attack only that site. There is no or very little silicate to abrade water pump seals.

You can now understand the difference - the silicates are "used up" essentially as soon as you put it in the engine. The long life coolant additives remain on duty until needed and can stand guard much longer. In heavy duty vehicles the coolant life is 250,000 miles and longer.

Want a demonstration? Get some Prestone Low-Tox (I'm not picking on propylene glycol, only the additive they use - and I just did this with this brand, so I know what happens) and a $10 non-timer coffee *** (so it stays on continuously). Put 10 cups total in the *** (50-50 mix) and turn it on. By day 2 you will have huge fluffy white snowflakes. Holy Cow, Batman! You can do the same experiment with a long-life antifreeze, but it will not have anything fall out.

GM uses DEX-COOL as factory fill, not because it lasts longer, but because it virtually eliminated warranty water pump replacements. All the stories circulating about lawsuits, sludge, destroys radiators, etc, were various very poor housekeeping or underfilling by GM and not a DEX-COOL issue. Japanese OEMs still prefer non-silicate, many others, including Mopar, have a "hydrid" that is low silicate. The technical debate is how much fast-acting silicate is needed, since the opponents see the non-silicated additives as "too slow to react."

Chad, consider a long life coolant and extend your flushes to every 5 years, although I'd like to hear that you reached 150,000 miles first.

Rogue, search some very old posts on this forum - there was someone doing exactly the same as you and ended up with a swiss cheese block. Please, buy yourself some Zerex Racing Super coolant, as that is the corrosion additive package used in anti-freeze, but without the glycol. You'll have "big company metal protection" and the better heat transfer you want.

 

[Copernicus]

Tom, a while ago, I had read some articles stating a class action lawsuit was pending against GM for corrosion and premature wear caused by sluding from defective Dex-Cool product. Admittedly, I have not seen nor heard any updates regarding this. Can you refute the validity of any of these claims?

 

[Tom F&L GoR]

As a then-Texaco employee, Texaco (not me personally) was called in because we were the factory fill coolant supplier. The GM product was the first non-silicate coolant to market in the US, so there was a lot of the typical "gee, nothing changed except we switched coolants to this new stuff." Actually, GM underfilled lots of small SUVs and because the radiator cap is remote (exactly same configuration as Vipers) nobody could tell. Besides, who checks the antifreeze on a new car? The excess air caused metal parts to get wet, dry, get wet, dry... and the air itself aggravates corrosion (oxidation.) Any antifreeze would eventually form sludge. These car owners wouldn't know anything was wrong until it overheated and of course, by then, it looked horrible. In a Saturn plant situation, they mixed the coolant lines with something else which caused other problems.

The opponents won a few public opinion battles because the laboratory bench tests often could make traditional coolants look better than new technology coolants. That's because the industry data set used to correlate bench to field performance only contained traditional technology, not the newer. Once the technical societies reviewed the data from field tests with new technology, more appropriate tests were developed at the bench. One example of the bench test problem was that someone "predicted" a mixture of new and old technology could be worse than either one alone, so never to mix them. The field data later revealed this just did not occur.

I think the true test is that GM still uses DEX-COOL as factory fill. If it was problematic, they would have switched or changed the specifications shortly after the field problem. Similarly, other companies have DEX-COOL products, low or no-silicate products, and "everyone" has one now.

 

[Copernicus]

I should have read your first post more clearly as it seems you touched upon it briefly already. Thanks for your input.

If I'm understanding points mentioned in your second post, there are no problems removing the traditional green antifreeze and replacing with the newer formulation Dex-Cool?

 

[Tom F&L GoR]

Nope. That's what I did.

When I bought my '94 in '98, I noticed a bad solder on the radiator and got a new one mostly because it was free under the extended warranty that came with the car. Installed Havoline DEXCOOL with that new radiator. Slight fluid top up after the thermostat gaskets needed replacment, then again a few years later when the heater hose rubbed through against the firewall. Had a cam change last year, (a roller lifter lost a roller) so the fluid was essentially 6 years old. With the heads off, could see that all passages were fine.

If you are the least bit worried about "DEX-COOL" products (which are no-silicate), then at least get your favorite brand of low-silicate hybrids. There is nothing good about pumping abrasive jello balls - it's kind of like extrude honing your cooling system, but with bad results.

 

[Copernicus]

OK, I'll look into doing this. And just to make sure I'm 100% clear, the validity of the claim that Dex-Cool mixed with even trace amounts of the traditional green antifreeze can cause problems is overblown? I plan on doing a fairly complete flush and am simply trying to assuage concerns of what I was previously told regarding mixing the two formulations.

 

[Tom F&L GoR]

DEX-COOL mixed with trace amounts, or the "retain" amount during a flush is not going to cause any problem. Texaco published SAE paper 2000-01-1977 demonstrating the bench test would predict a poor result from the combination, but that field results from "flush and fill" vehicles had very good results. I can email this paper to those interested.

 

[Tom F&L GoR]

Another SAE paper 2000-01-1976 has a Daimler/Chrylser co-author. Dodge 2.0L, 4.0L, 5.2L. 5.9L, 2.5L, 2.7L and 3.5L engines were used. It examines the use of propylene glycol and recycled propylene glycol with extended life inhibitors. It also mentions mixing with ethylene glycol antifreeze and the dilution with the associated corrosion additive technology. Everything came out fine.

 

[AviP]

I think I use Prestone 5yr/100K (orange color) in mine. Flushed it about 3 years ago and that was the only thing available. I'll probably do a drain, flush, fill next year.

 

[RoadiJeff]

Here's a warning to anyone who plans on draining their cooling system. Do not use the radiator drain plug to drain it. The metal around the plug is very thin and if the plug is fairly tight you can destroy the radiator quite easily.

Remove the lower radiator hose off the the radiator to drain it.

 

[Copernicus]

Good tip, thanks Jeff. Thanks Tom on the clarification. This is on my list of maintenance items for the upcoming down months.

 

[Kevin ACR]

Excellent information, changed my thinking on Dexcool.

Question for Tom:

My car is due for a coolant change and after reading this thread I want to change over to dexcool.

I have the car on the lift for the winter.

Do you recommend I put the effort into changing over to dex now, is there any detrimental effect from leaving what I have sitting in the non running car over the winter? I'll maybe start the car a couple of times.

I'll change it now if it benefits the car, otherwise I'd just as soon do it in the spring time.

 

[Tom F&L GoR]

I believe in DEXCOOL and have it in my car. If you want something 99% as good (in my mind) then consider the Mopar approved hydrid also - 5 years, 150,000 miles and probably no measurable difference on water pump life. But it'll maybe save you some arguing with someone down the road.

Corrosion happens dramatically faster when temperatures are high, so leaving it sit (with a few starts) won't make a difference.

If you try the coffee *** test, you'll see it'll stay normal looking for a long time at room temperature, yet 48 hours at 160F (a covered coffee ***) will drop out the additive. Isnt' additive science cool?

 

[Ron]

Thanks to several conversations with Tom I switched all my cars to Dex-Cool 5+ years ago, including my Viper. Had to change hoses on one and a thermostat on another and in both cases the inards looked fantastic. I'm a beliver.

 

[GTSnake]

Where do you guys dispose of the old coolant? Does the city recycler generally accept it?

 

[Viper Fever]

Question; When you say flush the coolant system what does that mean and
what is the proper method .I realalize that you put " New " coolant in
but how and what do you flush the motor and raditor with. This is my
winter project as well. Also is there anything that aids in making
this less painless for do it yourselfers.Thanks

 

[Ron]

I have a friend with a repair shop that accepts the old coolant.

My "refresh coolant flush" (not, oh crap! corrosion flush) includes the following:

Turn heater on full. Drain rad, block, expansion tank and overflow bottle. Refill same with distilled water, burp air out of upper hose a bit, and bring up to op temp. You will see a temp spike just prior to thermostat opening because base of stat is in air, not water. I minimize the impact of that by turnig off the idling engine just as the spike begins and then let the heat soak open the stat. Let water circulate for a few minutes, then kill the engine and let cool almost completely. Drain all again, replug everything, and fill rad with 100% coolant of your choice. Amount based on 50% of system capacity. Top off with 100% distilled water as that plus trapped water should = a 50/50 mix. Add 50/50 mix into overflow bottle then burp engine extensively.

Some use upper hose as a fill point to minimize trapped air, some use heater hose for same. Some use upper to fill and heater to give air a way out. All good ideas. Burping instructions found via search.

If you're changing coolant type (green to Dex-Cool for example) I'd suggest 2 or 3 distilled water cycles. Maybe the first tap to save the trip to the store then the last 2 distilled. A full day job done right if you let it cool down. Block plugs are lock-tited pretty bad, but can be anti-seized on replacement. A search will tell you where to find the right wrench for the block plugs or how to make your own. As someone else mentioned rad drain has a weak surround. Turn it while at a perfect 90 degree or you'll be buying a new rad. The thermostat housing has a nice air bleeder port but the super lock tite the factory used precludes opening it via normal methods. Be careful if you try. Suggest removing when you have it off for a therm replacement and antiseizing or replacing with a brake bleeder for easy future use.

There's a more detail instruction post somewhere in the past, try a search to find.

 

[Tom F&L GoR]

Science Fair time. Here are pictures from the 48 hour coffee *** test. Image this being pumped around inside your cooling system.


In the bottom of the coffee *** (nothing has been added, only heat):

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The jelly-like cloud poured off into a small glass container. Note the solids that are on the side of the glass above the liquid level.

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