My car has 72 k miles. Brake 4less inspected my car and told me I needed to replace the master cylinder. I was familiar with the online prices and mentioned to the tech. He told me he will give a good price. Now, I found out he did not installed a new part but a rebuilt and used my old reservoir. I read you can place people in danger with rebuilt ones. I am afraid to drive my car and the shop refused to correct the problem. Is it really dangerous to drive with partial rebuilt master cylinder and my old reservoir? I was charged over 200.
There are probably hundreds of thousands of cars on the road with rebuilt brake parts, some including the master cylinder. If the rebuild was done well, you should have no problems. For many older cars, the only choice is rebuilt. The difference in cost can be quite large.
I don’t like chain shops at all, but you given no reason in your post to suspect you have or will have any sort of safety problem. What is the “problem” that they refused to correct?
You can place people in danger with brand new ones if they have a build flaw in them.
The reservoir is a tank that holds brake fluid. If there aren’t any holes in it to let the fluid leak out, it’s silly to buy a new one. And rebuilt is fine. A rebuild replaces the parts that wear out while leaving the metal structure, which doesn’t wear out. There’s no need to have a whole new metal piece built unless the old one somehow got damaged (and it would pretty much require malicious intent to damage it).
Do your brakes work with the rebuilt MC in there? Then they work, and you’re fine 
$200 or so is a pretty good price for that job. After all, I recall getting jumped on by some on here for being annoyed that a shop wanted to charge me $600 for the same job. If my shop had charged what your shop did, I’d have let them do the work instead of doing it myself.
They made me believe it was a new master cylinder and the owner concealed the fact he used a rebuilt part and used my old reservoir. I found out when I asked him to give me the old part as my husband wanted. The brakes are spongy and not better than before.
There is nothing wrong with using remanufactured master cylinders, brake cylinders, or brake calipers on a car, as long as the parts are rebuilt by a reputable company.
When they take the old worn out parts off of your car, the old parts then get shipped off to the rebuilding company, and are typically cleaned up, taken apart, measured, and then have all the rubber and plastic parts replaced with new ones that bring the tolerances back into spec. These rubber and plastic parts are typically coming from the same exact company that supplied them to the company that built your car.
If the brakes feel perfectly fine, and they should feel much better than what they were before the repair since it was determined that the m/c failed on your car, then you really don’t have anything to worry about.
BC.
Cut your losses and find a good mechanic (you probably won’t find him or her at some chain shop). Get brakes fixed before something bad happens. It doesn’t matter if they use new or rebuilt parts to fix it (other than the cost), but it does matter if they do the job correctly and do what they said they would do when they gave you the quote.
The vast majority of shops do not place part in that will fail. They go to a supplier they can offer decent price to customer, decent profit, availability, and fewest call backs.
Remember they are on the hook for a period with parts/labor and using bad parts does not make sense for any business out there.
Online work to a degree for local shops however a customer sits waiting out of a car for parts delivery. The local parts are more due to mechanic profit(deserved), and distribution chain (delivery of part to place within hour(s)) etc.
the reservior is just snapped, screwed or pushed on to the top of the master cylinder.
just because they used the old reservior, doesnt mean you got a bad brake job. However there is NOTHING they can ‘do’ to your old Master Cylinder. it has to be rebuilt by a remanufacturing business. a local discount chain does not have this capability.
BUT you mention the brakes being spongy. this IS an indication of either a partly bled, or poorly bled brake system. you do have a valid point to return to have the brakes bled to correct the problem.
You read wrong and the open possible issue I could see here would be the spongy brakes.
This could be caused by some air still being present in the brake lines or worn/out of adjustment rear brakes IF the car has drum brakes on the rear.
Whether it’s got drums or not I have no idea because you did not specify the year of the car but a problem in the rear brakes can mimic a failing master cylinder.
Just to clarify, master cylinders – at least rebuilt ones and maybe new ones – often ship without reservoirs. Reusing the old reservoir is a normal practice at least on the cars I’ve owned.
As others have told you, the brakes should not be spongy. That’s indicative of not bleeding the air out of the brake lines or the master cylinder itself. The shop should certainly have checked that and if it isn’t a problem they caused, they should have told you what the problem is, why it’s unrelated to the replacement master cylinder, whether it needs to be fixed, and what a fix will cost.
I reckon that I’d find another mechanic.