You should leave the repair work to the professionals, I must acknowledge that there are, in fact, some points you can take care of yourself that will save you lots of money in the long run. The thing is catching the problems early. If you have a rumbling sound coming from your engine–a low-pitched sound, that is, or random, rhythmic thumping, face the fact that you have a problem. The earlier you accept that, the sooner you can begin to work on it. Again, the key is to wait until your car cools off. That frame of time is usually an hour. Placing yourself under a still hot car is setting yourself up for a possible serious injury.
Once your car does cool off, place a jack under your car, and do some investigative work. As Vida Joy Carlos points out, it could be as simple as taking a common screwdriver and tightening up a loose muffler, exhaust pipe or converter. But before you conclude that it’s just that, do some very careful and responsible troubleshooting. Listen for the right noises. If you hear a thumping sound, the problem, most likely–is a loose muffler or exhaust pipe.
Look for the muffler beneath the seat, 3 feet behind the engine. Take your screwdriver, and tighten it up. While you are doing so, also be willing to do some additional poking and prodding, as you check for other problems. Listen. Do what you can to try and recreate that sound that your car makes while you’re driving. That is very important, as Carlos points out.
When DIY Muffler Repairs is No Longer Appropriate…
If you cannot fix the problem even after tightening the loose parts with the screwdriver, that is a sign that your problem of engine knocking may be due to a deeper problem with your muffler, or some other part of your car. Please do not delay–get it checked out, the sooner the better.
But do not go to the first auto center you see. Check several out, compare prices, and ask for references. This is a serious decision, as you don’t want to go anyone whom you can’t trust to get the job done, and get it right the first time. Muffler repairs can be a lot of money to pay for someone who doesn’t do a good job, and still demand that you pay them. You could be out of a lot of money, and you may be out of an otherwise good car too.
Pay attention to your car. Don’t jump for joy just because the problem appears minor. Check further to rule out the possibility that something that can’t be fixed with merely a few moves made with a screwdriver. Sure, muffler repairs may be costly, but you may find yourself paying the same amount of money and more, if the problem remains un-diagnosed. In addition, you could allow your warranty protection on your car to become void.
For example, look at the internal temperature of your car. If it constantly shows a reading in the 80s or above, that means your car is overheating constantly, and the possibility that something is amiss with your muffler becomes more likely.