In my experience along many years (at least 32 or 33), one of the worst options to maintain and fix my vehicles, is the "dealer" shop. But many other shops are mediocre ones. That's why I prefer to make 99% of my repair and 99%+ of the maintenance of my cars at home.
(the only service I remember that I HAD to order in the last years, was a brake system hydraulic fluid purge ("bleeding'), and that is only because present day automotive "engineers" are terrible designers, and had made pedal purging impossible, having placed hydraulic brake lines full of up and down curves and empty ABS valve housings where air accumulates when one changes de brake fluid... and the brake cylinder hasn't enough volume to displace those air bubbles completely, REQUIRING a power flushing device to achieve a COMPLETE air purging).
The reason Dealer's shops are so bad, is that Dealerships have high operating costs because the locations need to be large enough to accomodate large and spacious new car showrooms, plus spare parts space, but because they sell fewer parts at those overpriced amounts, they end up selling much less and then they go the easy route to overcharge in all services. Because they pay low salaries to their mechanics, the average mechanic prefers to work for other shops, as Dealerships press on them too hard, assigning impossibly short repair times, which causes many mechanics to leave soon, lowering the expertise of the personnel. All this ends up producing a stong tendency to make sloppy repairs by changing parts instead of carefully analyzing the real problem. It is faster for a mechanic to just change the part than to try harder to analyze the root problem. And the poor client has to pay for all those inefficiencies! The Dealership looses money because the parts department ends up supplying too much parts that didn't need to be changed at all... and many customers return to demand more repair time because the Dealer shop did not fixed the problem. A perfect vicious circle!
On the other side, the absurdly stupid (ab)use of electronics on recent cars, make them difficult to fix, to start with. Even when recent models have improved reliability over the first three or four years, they are much more difficult to service because so called automotive "designers" have produced the worst designs of all time in respect to component placement, free space under the hood, and a complete lack of actual experince with the repair ability aspects! They could be expert AutoCad manipulators, but the worst "designers" of all time, no doubt. Heck, I could write a whole book full of real life examples just describing how failed are today´s underhood designs! Amclaussen.
I too have experienced the same problem with a radiator cap. I was a student, so I didn't have much money. I had to start replacing the cheapest parts. A new thermostat didn't cure the problem, but the replacement radiator cap did. This is not the normal way I troubleshoot problems, but it worked in this case.
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