Using water from the dehumidifier sounds good on the surface, but it IS NOT a good idea. Working in aerospace on a variety of test setups we found that using distilled water (which is what you are getting out of the dehumidifier) causes corrosion to softer metals. Pure water is aggressive on absorbing minerals which ultimately causes the corrosion. The way we got around this is to use de-ionized water, which is more commonly known as softened water. De-ionized water does not remove all of the minerals but replaced the harsh and heavy ones with minerals that are not as corrosive. Ask a plumber in an area where there are high quantities of minerals in the water about how much difference using a water softener makes on corrosion and mineral buildup on the plumbing fixtures. The aluminum used in modern car radiators and heater cores will see a much shorter life with distilled water.
As for the heater core buried in the Olds being difficult to work on, GM has been notorious with making some 'features' on their cars difficult to work on only to discourage the do-it-your-selfer's (like me) from working on their own cars. That way they have an extra avenue of income for their service departments...
I learned a long time ago when changing the coolant in a car's system that you could only drain about half the coolant according to the owner's manual. Being fairly anal about my own cars, I did not like the idea of adding new coolant to old, so I devised a method of flushing out all the old. Some blocks are supposed to have drain plugs into the water jacket, but these are usually inaccesable when the engine is still in the car. When Prestone came out with their "Tees" to splice into the top most heater hose that would accept a garden hose fitting, the solution was easy. Forcing water through the block would quickly result in clear effluent from the system. I would run the engine until the water was warm enough to open the thermostat and turning on the heater would flush out any hidden reevoirs of old coolant mix. My source of de-mineralized water is condensate from a de-humidifier, and if anyone knows why this would be bad, please educate me. After shutting off the garden hose and draining, I would pour two gallons of dm water at the highest point allowing it to drain and hoping this would either flush out the city water at best or dillute it sufficiently at the least. Then, finish by closing the radiator petcock and adding 100% antifreeze to the proper level. A few minutes of running the engine should result in the recommended 50-50 mixture.
I've often said that automotive engineers should be forced (yes, forced) to perform routine maintenance tasks on the cars they design using standard tools. Such the case of a 1982 Buick Skyhawk I owned. To change the thermostat, it was directly using a pressure relief cap (radiator cap) on top of the engine. However to change the oil filter you had to remove a panel from the wheel well. Also a 1972 Plymouth Fury with a 400 engine comes to mind. To change the spark plugs you had to crawl under the car, and one of the those on the rear of the engine required you to jack the engine up slightly. Actually, it all comes back to where they want you to have to bring it back to the dealerships for service. Alas, we mourn the demise of the shade-tree mechanic.
But by what criteria have cars improved? The old air cooled VWs used to get 30 mpg, and you could do a clutch in half an hour. They last nearly forever, and it is common to see nice looking Bugs and Buses on the road that are over 50 years old. And not only that, they were safer in an accident. They had more crumple zone in the trunk, and did not explode an airbag aimed at your face.
The main change is that newer cars accelerate better, but at the cost of constantly having to change timing belts, replace expensive turbo chargers, etc. Not worth it in my opinion. I would still prefer is they made new production of the old VW bug, Saab 96 or Sonnet, Fiat 850, and even the Corvair. These were all better cars than they make now.
I must be very lucky since I have not had to replace a heater in all of my many cars. Of course I did change antifreee occasionally and I did add those corrosion prevention chemicals on a few occasions. I did need to replace the heater on one used car that had ben full of plain water and froze, prior to my buying it. That was a 1965 Barracuda, and my reollection is that the job was not that hard. BUT cars have changed since then, mostly in the requirement that they protect people who are to lazy to buckle up, which has fundamentally altered the entire structural design of the car. In addition, the entire shape of the passenger compartment is different, and may continue to change as the design evolves. So I wonder about what area of engineering those people who say it is easy and simple to design a heater that is simple to replace. I know that it was easy to change them in the older pickup trucks, which was because they were an option in those trucks long after they became standard items in cars. And optional items are often much easier to replace.
It is a dramatic design flaw to make heaters difficult to change. They often go bad. It is not usually from corrosion, but simple construction flaws. You can not crimp aluminum onto plastic and expect it to hold up to engine pressures. Sure they do not fail often, but failure MUST be allowed for. And curreent designs are absurd. Heaters are not at all difficult to design so as to be easy to replace. Fiat and Jaguar put then right in the engine compartment. Anyone who makes them hard to replace is simply an idiot. There is no excuse. It is simply sloppy engineeering to try to make excuses. That is not at all acceptible.
That is totally and completely false. Corrosion inhibitors are not something you add and they do not wear out. That is impossible. The aluminum simply wants to go to a +3, and you have to ensure it can't do that. You simply can not allow coolant that will accept electrons. Aluminium engines have been around since before the 1940s. They are not at all new. Merceders, Fiat, Corvair, aircraft engines, etc., give us a very long history of knowing how to deal with alloy engines. And with all alloys, the corrosion happens right away. There is no delayed actions, and things do not get worse over time. So once the initial corrosion has occured, then the combination of coolant and block become neutral once again. There is nothing to decay, and I resent the marketing hype of products that claim you do have to replace them as transients. That is not how chemical compounds work. They become neutral after the first week or so, and after that there is absolutely no reason to change them. In fact, changing then on a regular or annual basis only invites more corrosion as the new fluid has to once again accept whatever electrons it can, from the reactive aluminium. The reality is tha once equilibrium is established, it should always be left alone. If what you have contradicts that, is it no informaiton, but marketing hype, and is best left out of technical discussions.
If you maintain the coolant then the core doesn't fail. Heater cores were not intended to be replaced. Sometimes things fail, but not often. That is why they are hard to change. Besides that, the heater core is relatively heavy and needs much more support, which is provided by the fire wall. So it goes on first, then the lighter parts, such as air ducting, dampers, and the blower assembly. Then the rest of the air ducts and the dashboard go on top of that. In the real world it is referred to as a sequence specific assembly. Any other design would take up more space and cost more. So it is not a design flaw, it is that the design was optimied for other parameters than easy replacement of the heater core.
I worked on auto A/C for a few years in the early 90's. Some of the heater cores/A/C evaporators were a nightmare to change. T-Birds andLincolns required 10-12 hours, and removal of the windshield, to get at the dash, which also had to be removed. Volvos and Beemers also in the 10-12+ hours ranget to change A/C stuff. these labor estimates were from the Dealer Service Books.
Ford Ranger pick-ups were a 5 minute job, and that was taking your time.
Sorry to disagree, but in addition to assembly time constraints, many many cases result from sloppy work, lack of attention to detail and pressures to use a given component ("commonality" constraints) that plainly DOES NOT FIT well. Abuse of AutoCad or "design" software is another factor. The so called "designers" throw drawings that only show apparently everything "fits" somehow... but these young and hurried monkeys have NEVER held a wrench in their hands, much less understand maintenance or repair (I guess they believe cars must be disposed of after a couple of years). In the old times, a solid 'mock' model of the complete engine bay was built and checked, and the (usually) very experienced supervisors, ran a hard inspection before approving a design. Any changes were carefully checked by several people, and therefore cars were much more easier to service, independently of their complexity or abundance of accesories. Anyhow, 300,000 miles is not bad!
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