VALVES/PISTONS DROP MESSED UP HEADS?

You're obviously dealing with a pretty reputable company if they're still willing to cover half the repair after this much time. Most of the better dealers give a 30-day 50 / 50 warranty to cover the multitude of potential problems there's no way to foresee. They do that to offer peace of mind to their customers. Basically the half you pay covers the parts and the mechanic's labor. The dealer doesn't lose, but they also have their mechanic tied up so he can't be working on other customers' cars.

If they give you the option, I would let them make you an offer on trading the car for a good one. I use the Rock Auto web site a lot for reference. If you look up a car you're interested in, then click on "Engine", then "Timing Components" or "Timing Belt", it will list in the part description if it's an "interference" engine. That is what you have and there is no reason to design an engine that way. This means if the timing belt breaks, or if it jumps a few teeth, as they all do at some point, the open valves will be hit and bent by the pistons as they coast to a stop. This is why it needed the original repair and is likely why the last owner traded it off.

The half of the repair they're expecting you to pay is more than the car is worth, so you'd be better off putting the dollars toward something else. It is possible for a valve seat to drop but it's not common on any car model. The cylinder heads are made of aluminum to save weight, but the seats need to be made from hardened steel. Aluminum in this application would wear out in a few miles. The seats are rings that are pressed into machined holes in the head, then friction holds them in. There really isn't anything a mechanic can do that would lead to one falling out. I suppose the previous bent valve could have pounded on it a little and loosened it up, but I've never run into that before. A more common cause of this is overheating the engine. That makes the head expand too much and deform, and could allow the seat to work loose.

That's a copy of your original post, and I more than answered your questions already. The engine had to have been repaired properly. As proof, the engine ran okay when you test-drove it before buying it and for two weeks. If something had been done incorrectly, you would have noticed that right away and not bought it. I would need a couple of hours to list all the things that can go wrong with a car that mechanics and salespeople have no way of knowing are going to occur. Of course the mechanics are always to blame for not being able to foresee those things. The dealer, on the other hand, gives you some type of warranty in case something unexpected does happen. If they could be sure nothing would go wrong, there would be no need for a warranty.

The best advice I can offer now applies to any car with an interference engine. Every manufacturer spells out a recommended replacement interval for the timing belt. Some brands have a history of the belts breaking before that mileage is reached, resulting in an expensive valve job and cylinder head gasket repair. Some brands go a lot longer than their recommended interval so people get complacent and get caught with a broken belt that was ignored for too long. Some brands, like Chrysler, have an Engine Computer that will shut the engine down to protect the valves if the timing belt jumps as little as two teeth. I'm sure there are a few other manufacturers that do that too, but that still won't protect the valves if the timing belt breaks.

You are also supposed to replace any tensioner and idler pulleys when replacing the timing belt, and any tensioning devices. Some of those are just spring-loaded pulleys, and some are little pistons that fill up with pressurized engine oil to hold proper tension on the belt. On a lot of engines the water pump is also driven by the timing belt. No conscientious mechanic who has your best interest at heart will agree to replace just the belt without all those other parts, and you don't want to work with a mechanic who would cut corners like that. Those parts provide the insurance you're getting a quality repair service. You and your mechanic don't want a $2000.00 engine failure because of a failed bearing in a 20-dollar idler pulley or a 50-dollar water pump

Hmm. I'm wondering what kind of test would lead to a valve seat diagnosis without taking the cylinder head apart.

If I was an average consumer, I would suggest you were taken advantage of, but after being on the other side of the hood, so to speak, for many years, and having my customers' best interest at heart, I know that about 98 percent of the time, things get lost in translation. Mechanics typically have very poor communication skills, except when talking with other mechanics. The same is true of many doctors, carpenters, and accountants. Add to that the fact you often have a service writer as a middleman, and he usually was never a mechanic, things get even more confusing. In the past when I was asked to interpret repair bills and estimates for students and other instructors, they almost always had a better understanding after the explanation, and realized they really were well-taken care of, they just weren't aware of it.

If you feel like it, please post a follow-up in a month or two to let me know how it's going.