How-To Repair a Damaged or Rusted Exhaust System

Posted: July 13, 2015 By: JamesR

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Unless your car has a factory stainless steel exhaust tubing it is only a matter of time before the elements compromise the integrity and functionality of one or many parts of the whole system.  Nothing is worse than the constant ticking sound that is the most apparent symptom of a damaged or broken exhaust system.  From the factory many cars are equipped with what is called aluminized steel exhaust tube, this type of tubing is much better than mild steel tubing because the infused aluminum helps resist corrosion and rust from forming.  The tubes themselves do an “ok” job of resisting rust but more often than not the welds joining the aluminized pipes to mufflers, resonators, flanges, etc. are done with mild steel welding wire and are not treated to resist corrosion.  The exposed steel welds become much more susceptible to rusting once they come in contact with water, salt, mud, or anything else you may drive your car through.  These welds can hold for years but eventually, like all steel does, it will rust out.

You may also encounter exhaust issues when buying a used car.  It is tough to know everything that has been done to a car by the previous owner/ owners.  I encountered this issue when this car was purchased claiming to be “stock”.  The seller was not lying because it did have the factory exhaust but what made itself very apparent is that the factory installed muffler spent some of its life off of the car.  The car slowly became louder and louder until eventually it sounded as if there was no muffler on the car at all.  At some point one of the previous owners must have installed an aftermarket exhaust system in place of the stock unit and when it was time to sell the car a quick repair job was done to re-attach the factory muffler.  The fix was done very poorly and slowly but surely it rotted away, leaving the muffler suspended by the hangers, completely disconnected from the rest of the exhaust system.

In this article I will show you step by step how you can repair a damaged or rusted out exhaust system so it will be able to withstand the elements and be able to drive without the worry that sooner or later you will need to fix your exhaust system.

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As you can see here this exhaust system was not mended once but twice, both times improperly.  Once the weld from the original patch job broke a band style clamp was put over the pipe to reconnect the pieces but neither repair was a success.  Fixing your exhaust system like this may work temporarily, but in the long run it will always come back to bite you.  When working on cars its always best to take your time while doing repairs because when a repair is done correctly it will never appear again allowing you to be worry free when driving your car.

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To tackle this exhaust repair I first had to get the rear portion of the exhaust system out from under the car.  This was done be removing the factory band style clamp which is in front of the resonator and also by two hook style hangers which were holding up the muffler and exhaust tip.

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With the pieces on the table I was able to get a much better look at the condition of the pipes as well as figure out the best way to fix the problem.  As you can see here the rust is very bad and in order to properly fix it the entire section must be cut out an a new piece of pipe will need to be welded in.

measurement 1

Before I started cutting away the rusted pieces I clamped the resonator down to my workbench and held the broken pieces together in the correct orientation.  I then used a metallic permanent marker and straight edge to draw lines the length of the area that needs to be replaced.  Not shown in this shot, I also drew lines on either end intersecting the first lines; I then measured the distance between each of crosses and wrote them down for use later.  This is very important because without these marks as a guide it is nearly impossible to make the repair and maintain the correct angles so the hangers will line up and the exhaust tip will sit square and even in the bumper cutout.  (Make sure the alignment marks are far enough away from the repair area so that while cutting out the rusted pieces you won’t damage or destroy the marker lines)

measurement 2

After I have all my measurements down I began to cut off the old repair by using a cut off wheel on an electric angle grinder to cut off the rusted patch piece then a grinding wheel to smooth out any rust or metal that is still remaining.

measurement 3

With all of the old repairs removed I then cut a new piece of exhaust tubing that fills the gap between the old pieces and also allows the two pipes to slip inside.  (In this case the outside diameter of the original piping was 2 ¼” and the new piece had an inside diameter of 2 ½”) this creates a small gap that can easily be filled with a MIG Welder.

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Using my Eastwood MIG 175 I tacked the new piece to one of the two sides and using the alignment marks and measurements I had written down earlier I was able to fully weld both sides of the joint without worrying that the now solid pipe was in the wrong orientation.

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After both joints were fully welded I went back to see if there were any pin holes in the welds.  Next I took a wire brush and cleaned off the welds and surrounding metal to be painted.  In order to properly paint any parts of an exhaust system you must use paint that is rated to a very high temperature, this rules out your standard off the shelf spray paint.  For this job I used Eastwood’s High Temp Factory Engine Coating which is rated to resist heat up to 1400 degrees

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Now after the exhaust is remounted under the car the exhaust tips sit evenly inside the bumper cutout without having to make any adjustments.  This is possible because the measuring and alignment that was done earlier ensured that once the new piece of pipe was welded in the whole exhaust system would maintain its original orientation and once done appear as if it was never damaged in the first place.

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