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[Bruce Nunnally]

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[Bob*97 SLS]

I found this to be a good post for saving.

Posted By: bbobynski

Subject: RE: Half life report

Date: 12/6/2002 10:13:17 PM

Cadillac: 2003 deville

Because to most people flushing the cooling system involves pouring in some sort of caustic cleaner or "radiator flush" which can damage the system....and it is then almost impossible to get all the "flush out" With an aluminum engine and aluminum radiator you really want to be careful about what you put in the system (and leave in there) as it requires proper corrosion inhibitors to prevent corrosion induced damage and you DO NOT want to put something in there that cannot be totally removed like the cleaners. Besides, unless you go to extremes and do it with distilled water (not available in a garden hose or under pressure) you'll end up with , at the very least, quit a bit of tap or well water in the system after flushing which in some areas of the country will be just as bad, if not worse than, leaving the chemical flush in there. Besides, if the task becomes very onerous like draining and flushing and refilling and testing and adding, etc. the job gets put off.... If you just drain and refill with fresh 50/50 occasionally the system is much better protected and the job is very EASY and fast and it doesn't get put off then. The proper concentration is very important and if you flush with plain water, you cannot get all the water out so you end up adding straight coolant and running the engine and testing the strength and then draining some out and adding more water or straight coolant to get the strength correct at 50/50....pain in the *smurf*. Just drain what is available and refill with 50/50 coolant/distilled water and go about your business. Very simple and easy and better for the system than introducing non-distilled water, alien chemicals and possibly ending up with a non 50/50 mix. The DexCool , in particular, can actaully be corrosive if not mixed properly. Especially if the strength ends up bing greater than 50% of coolant.

I think the need to "flush" comes from pre-historic times with cast iron engines which rarely got the coolant changed and the systems would eventually plug up with rust. Since cast iron takes forever to rust thru due to the thick walls and the coolant gets "red" with rust when it was time to change people ignored the cooling system until the corrosion inhibitors failed, the engine parts rusted until the rust plugged up the system and it overheated. Then they "flushed" it out and put new coolant in. The engines were rarely if ever damaged by this due to the impervious nature of cast iron to rust.... Aluminum engines of today are a completely different breed. First, the coolant corrosion inhibitors can fail, the aluminum starts to corrode and the coolant still looks perfectly green and clean so there is no visual warning that the coolant has failed (depleted corrosion inhibitors) so you can't rely on that. Secondly, the engines and aluminum radiators are easily damaged by corrosion including head gaskets failures, cracked heads due to stress risers induced by corrosion pits, etc. Third, the aluminum actually has a greater tendency to corrode than the cast iron (even though you can't see it so the corrosion inhibitors are used up iat a far greater rate than with cast iron engines.. None of this is "fixed" or helped by drastic flushing or cleaning of the system... It is fixed by regularily changing the coolant and putting in fresh stuff. So just drain and refill regularily and it's actually easier.

The transmission "flushing" generally requires hooking your trans up to some shop's flushing equipment that pumps fresh fluid or even a solvent thu the trans to get "all" the old fluid out. Now figure the risk of your car getting flushed with the old fluid (and debris) from the last guys transmission by accident because the tech pushed the wrong button or hooked up the wrong hose or the shop decided to save some money by "recycling" old fluid thru the flush circuit.....consider that most transmissions go into a trans shop only when they have a problem and the owners pay for a "flush" in the off chance that it will "fix" their failing trans and the possibiliyt exists for a lot of debris to be circulating thru that flush equipment. I liken it to getting a blood transfusion with a dirty needle and an unknown blood source..... Why would you do it??? Just drain the trans fluid at the pan, refill with fresh and go about your business. See above logic also for making the task much more difficult than it needs to be. The trans fluid is good for a very long time as it is not continually contaminated (like engine oil) by by-products of combustion in the blowby gases, water , gasoline, particulates, etc. Since the trans fluid only sees heat, as long as it is at a reasonable temp it really only needs rare changing to boost the antiwear content of the fluid. This is easily accomplished by a simple drain and refill. One way that is a little more difficult but still relatively easy that works well is to take one of the trans cooler lines loose at the radiator, put the tube into a bucket, start the engine and start pouring trans fluid into the trans....the old fluid will be pumped into the bucket and the trans will get a pretty good "exchange" of trans fluid as it will push most of the old stuff out at the disconnected cooler line and you'll replenish it by pouring fresh stuff in. I think this is probably the best thing to do and I don't put this in the category of a flush per se. I just would not hook my trans up to some shop's flush equip, that's all, unless there is a real need....like the trans just augered in , there are bits and pieces in the oil and I really wanted to flush the cooler and cooler lines....then the risk is far outweighed by the consequences of leaving the junk in the cooler lines.

I think as maintenance intervals have been dramatically increased and the need for tuneups and general maintenance has been all but eliminated it has definitely cut into the revenue of service departments and repair shops and that the "flushes" and flushing equipment have become substitute money generator. Sounds like a good thing so people go for it when in reality it is totally unnecessary and potentially harmful to the system.

Just my 2 cents.....

bbobynski