Water pump and timing

Seems like your description is written in shorthand. It is hard to understand. The first issue is if your engine is an "interference" engine, it is the valves that get bent by the pistons as the pistons coast to a stop. If that is the case, that damage is what caused your engine to stall originally. That is definitely not the mechanics fault so do not falsely accuse him of causing that damage. When the valves are not severely bent, it is sometimes possible to get the engine started, but it will not run well at normal speeds. The only way to keep it running is to run it at high speeds. It will not be able to make normal power, but if that is the only way it will stay running, that is the clue he was looking for that told him to suspect bent valves. He could also do a "cylinder leakage test" that would show the same problem with the valves, but that can take more than an hour. He likely had your wallet in mind when he chose a faster test to save on labor cost, but you still called him "unprofessional". This is the biggest reason mechanics have such bad reputations. You don't understand why something is being done, so it must be wrong. They are held to much higher standards than are doctors.

To prevent this bent valve problem, all manufacturers specify a recommended timing belt replacement interval, and if you have a conscientious mechanic with your best interest at heart, he is going to push for a new water pump and tensioner pulley at the same time to insure the quality of the repair. Most manufacturers specify the timing belt be replaced every 75,000 miles, and a few call for as much as 100,000 miles. If you have never had the timing belt replaced yet, the damage is your fault for neglecting that recommendation. If the belt was replaced previously, I suspect the water pump was not, to save a few dollars. The damage you have now is what we want to avoid by selling you the water pump and tensioner pulley, but then a lot of people accuse us of trying to sell you unneeded parts. No matter what we do, we are accused of being incompetent.

I am confused as to why the mechanic is sending you to some other shop for the valve job. Most independent repair shops that can handle replacing a timing belt can also do the engine work. In many cases they will remove the cylinder head, then take it to an engine machine shop to have the valves replaced. When they get the head back, they install it and follow all the critical assembly procedures. They like to have the valve work done by the engine machine shop because those people are specialists and will get the work done a lot faster. Anyone can pull a tooth, but you go to a dentist for that. Anyone can do your taxes, but you go to a specialist for that too. You want the person with the right training and experience to do the job as efficiently as possible. That is why your repair shop might try to save you some money by calling on the engine specialist for part of the repair.

As for paying for the work that was performed, who else do you know who works for free? Regardless if the mechanic had taken the time to do the cylinder leakage test, or he first tried to get the engine started to see if the valves were bent, both methods require the timing belt to be set precisely to specs so the valves are operating in perfect time with the pistons. That means there is no way possible to know for sure ahead of time if those valves are bent. The best and most experienced mechanic in the world is going to approach this repair the same way. Every mechanic knows it is almost a certainty the valves need to be replaced, but what kind of names would you be calling them if they told you there was major engine damage before they checked to be sure? When you have a severe toothache, would you believe it when your dentist says you have a cavity before he even looked in your mouth?

In this case, the job is only half done, and remember, the second half of the damage occurred while you were driving the car, not the mechanic. Again, I am not sure why he wants to send you to a different shop, unless he is not equipped with the specialized tools to get into major engine work. Even if a different shop does the valve repair, they do not have to do the water pump and timing belt over. You can pay one shop to do the entire job, or you can pay half the repair charge to each of two shops. No one is ripping you off, but you seem to think it is okay to not pay the first shop because they did not or could not finish the job. Have you ever ordered a meal you've never tried before, in a restaurant, then refused to pay for it because you did not like it? When you get what you asked for, expect to pay for it. We run into this all too often when people do their own diagnosis, then ask the mechanic to do the repairs. If the mechanic does what you requested, you pay him when he's done. If the problem is not solved, look to the person who requested the service. When you ask to have a problem diagnosed and repaired, it is the mechanic and the shop that work for free to correct their mistake when they make a wrong diagnosis.

Unless there is more to the story that you have not shared, it sounds like your mechanic did not do anything wrong, and the real problem is that mechanics have very poor communication skills when working with their customers. They speak their own language, just like doctors, lawyers, and carpenters do. Your mechanic can tell another mechanic more about what is wrong with your car in less than five words than I can tell you in this entire story. I take the time here to describe the problem and solution as well as possible, and I still can leave you with some confusion. Now imagine how much more confused you will be when getting information from someone who is itching to get back to his current customer's problem. He is in a hurry to get back to work, and he is trying to explain what still needs to be done to your engine to someone who cannot possibly be expected to know what he is talking about. That miscommunication is a result of you not being an engine expert, and as such, it is the cause of the mistrust and frustration you and many other car owners deal with all the time. I will never defend a dishonest or disreputable shop, and I know of two in my city, but I will also not help you accuse a mechanic unless I think it is deserved, and then I have all kinds of solutions we can explore.

I spent an hour typing this wondrous reply. I expect you to ask me to clear up any misconceptions or confusing points, but if you do, please take the time to write complete sentences so I am sure I am reading what you intended to write. If you are tapping out shorthand on a cell phone, you are just as guilty of poor communication as are most mechanics, and I will not be able to understand you.

I am back already. I forgot to add that I cannot find any information on Renault products newer than 1987 models. Do not know why, but regardless, no car today is worn out at 140,000 miles, so unless it is rusty, hauling it to a salvage yard is likely not the best solution. Water pumps, timing belts, and valve jobs are a common repair on almost all car brands. You can also have a leaking cylinder head gasket, which is another common and expensive repair. For that, your mechanic will again recommend a new timing belt and water pump because the work to replace them is already more than half done as part of the head gasket repair. The love of my life, my extremely rusty trusty 1988 Dodge Grand Caravan died last year from a badly-leaking cylinder head gasket, (caused by me, but that is not at issue now), but I am not ready to scrap it. It only has 420,000 miles, and parts have fallen off due to severe rust. If I am willing to breathe new life into that van, I am sure it pays to do the engine repairs to your car.

CARADIODOC, Renault left the US Auto market in 1987 when they sold their remaining part of AMC to Chrysler.

True, but Renault is still around. I use the Rock Auto web site for reference everyday. They list every manufacturer throughout the world, since the beginning of the wheel, ... (Well, almost!), But even they only go to '87 with Renault. This is the first time I ran into this for a company that's still around.

Unless they have changed things Rock Auto only lists makes/models that were/are sold in the US, Canada and Mexico.
Renault came back to Mexico in 2000 or so but not Canada or the US. Just looked and they show Renault 2001-2017 in Mexico. Perhaps you have the Mexican flag unchecked?