Tips to Fix an Exhaust Leak

An exhaust leak will always need immediate attention, for two reasons – it will reduce the performance of your car for one and the gas mileage of you vehicle. The other reason is a serious health risk to all passengers in the car, as the exhaust fumes that leak will seep inside too. The easier way would be to hire a mechanic. But if you have the right tools and/or are maybe stuck somewhere on a road trip far off, here are the guidelines on how to find and then fix the leak.

Tips on Fixing an Exhaust Leak

Finding the Leak
Knowing how to fix an exhaust leak is pointless if you don’t know where it actually is, or how to find one. This will take time, depending on the size of the leak. One problem you should know is, if the leakage point is small, it will get shut off after using the car for some time, as the heat will make the metal around the hole to expand. So if you think there’s a small leak that you just can’t find, start your search after the car cools down to normal temperature. Now, there are two ways you can search for it:

  • The first one involves clogging your exhaust tail. Make sure you have your emergency brakes on. Then start your car up and gently accelerate. With the tail clogged, the fumes should try to escape from where the hole is. Ask someone to help you find out where the leak is as you accelerate. A larger hole should be found out soon enough.
  • Another way to do this is to simply go under your car and look for the leak. Prominent places where leaks will occur are the joints, welds, and rusted areas of the pipe. The points will certainly have telltale signs like small patches of burnt-out paint, or have a buildup of black carbon from the fumes on them, so keep an eye out for such patches.
  • Apart from these, always check your gasket and manifold. They are some of the first things to fault with age. Check for any cracks around them that happen with age or due to exposure to excessive heat.

Fixing the Exhaust Leak
Depending on the point of leak and the situation you repair the fault under, there can be several solutions on how to fix an exhaust leak. I have written what you can find helpful in your case.

  • In case of gasket fault, the best solution would be to replace the gasket. Make it a habit to sand down the ends of the pipe when you replace the gasket. You can also use fine silver spray-paint over the replaced gasket. This will seal off whatever minuscule air escape routes there are.
  • For faults in the pipe, there is a crude quick fix that will work for about 1 – 2 months, till you get your replacement done. Get a kit for fixing holes up. You’ll find a tube of high temperature-resistant putty or silicone in it. I would actually prefer JB weld, because silicone doesn’t seal as effectively as JB weld can. It can also create quite a stink if exposed to high temperatures for too long. If you have nothing else, slather the putty onto the hole to seal it up for a short time. If you can, get a tin sheet, curve it and add over the putty. Clamp the sheet to the pipe with the sealant in between, till the sealant dries up.
  • If you do not have the putty, you can saw off the part of the pipe that the leak in a V-shape. Get two tin sheets and roll them up, one slightly smaller and the other slightly larger than the pipe diameter. Place the smaller roll on the inside of the sawed off pipe. Make sure that it fits perfectly in. Place the smaller roll on the outside. You need to clamp the outer sheet using exhaust clamps. To be sure, use a high temperature-resistant tape or muffler tape, and tape the sheet to the pipe. Tape around it as many times to ensure that it remains air-tight.
  • For motorcycles, it is better to get new gaskets and clamps.

To be clear, all the mentioned solutions are only temporary. Most will last you for a maximum of 1 year or so, that too if you have done a good job in repairing it. Also know that while RTV silicone seems a good option, it lasts only till around 500 degrees, and will crack around the edges of the exhaust pipe after some time.