If you have purchased a second hand car that is below about £1500 then you can often expect to spend between £500 and £1000 per year on repairs and maintenance. Although this may sound a lot, for some people it is the only way they can afford to own a car.
You do need to consider if the car is worth spending that much money on or whether you would be better scrapping it and starting with something new.
It is a very hard decision to make as it may be that you spend a few hundred pounds on it and then runs well for a number of years, or you may find that you spend the money on it and it a few weeks or months later something else goes wrong which is going to cost far too much to fix.
Before proceeding with any major work it may be worth asking the garage to have a look over it and see if there is anything else that needs doing or may need doing in the near future. This will often give you a better idea as to if you should spend money on it or not.