Never Use Rope or Twine to Repair an Exhaust System

Okay, so we know you have a problem with your car. The muffler, tailpipe and resonator assembly are getting louder and louder and you can hear them banging away on the bottom of Old Faithful.

If you're like most drivers you probably figure you can lump it home or, at least, to your repair shop, but many times that doesn't happen and the whole shooting match takes one dip too many and it drops like a stone.

It's a sound you won't soon forget and it's a feeling you won't soon forget either because suddenly you are hearing an awful grinding against the roadway and watching sparks fly out from under your car, just like they do it in the movies, only here it's for real. This is if you're lucky. If you're not lucky, your car has probably pivoted upward on the manifold catalyst end of the pipe and you suddenly find your car's rear end sitting there swaying ominously as your car tries to set a new Olympic car-rear pole vault record.

At this point there's nothing you can do except wait for it to fall down and call a hook to get it out of the place where it's failed in the first place. Where has it failed? It has probably chosen the worst spot in the world. It is probably in the middle of one of your city's busiest roads, just at Friday night rush hour. And, just think, spending a few minutes time a couple of months back checking things have prevented this whole scene.

Well, that's history and the reality of the situation is what you have. And, while other stories here tell you that you can rope or twine the whole mess back together so you can lump it on home, take it from various automotive experts with whom this issue has been discussed endlessly. Stop and wait for the tow. It's that plain and simple.

Why Does it Pay to Wait?

Let's roll the film back a few years to say, 1982 or 1983, when the catalytic converter really became an essential part of your car's exhaust system. Indeed, the while the engine positions themselves have changed during the years, the essential layout of the components has not.

Starting with the air intake, you have a long run of flexible tubing that leads to either: a. a carburetor, b. a throttle body injector, c. a manifold that feeds direct injectors.

In turn, this system feeds air into the engine and, with the aid of the charging system and sparkplugs, gets the car moving. Now, since we're talking about your basic Otto cycle engine (four-cycle: intake, compression, spark, exhaust), the gases that have been built up by the combustion cycle have to go somewhere and that somewhere is usually through the output valves and into the exhaust manifold stream.

The first stop in the manifold stream is the catalytic converter where all of the nasties are taken out of your exhaust - oxides of nitrogen, CO2 and all of other gases - and turned into more or less harmless H2O, nitrogen (not oxides or acids) exhaust gases. Catalysts, by the way, do run red hot.

The next stop is the catalyst output pipe and on to the muffler. The muffler is a device that ontains the baffling that quiets any rough noise that might be coming out of the four, six, or eight manifold returns to the manifold pipe. The muffler, which does get quite warm, is actually just a hollowed out device that contains two or three rows of baffling material and effectively lengthens the exhaust system.

The next stop is to the exhaust resonator -- resonant pipes that take the quieted exhaust stream and further quiet it and then they send out out through the tailpipe.

That's a lot of verbiage to describe what is essentially the exhaust system of the car, but there is a reason it was mentioned.

Starting with the exhaust manifold, itself, the gases are quite hot and then the catalyst heats them up even more to burn out the bad stuff. Read your car's owners manual and you will likely see a warning against parking your car over leaves or grass while it is cooling down because the catalyst runs so hot that the grass or leaves can catch fire.

And, this brings us to the story where it was mentioned that twine or rope are adequate for temporary repairs to your exhaust system. No they are not because they can easily burn up themselves and cause a fire underneath your car.

Assuming Things Are Okay

So, let's assume everything's okay and there is no damage to the U-joint or banjo box in a rear-drive-car or the rear axle in a front-drive-car. Should you try to fix things yourself? Only if you enjoy lying on your back with all sorts of gunk falling down as you try to put things back together, should you try this. Wait for the hook and have it towed it. You'll be better off. Besides, you'll have to put your car up on either blocks or use the jack to do this and while the blocks are okay, the jack just isn't. It could fall.

However, if you must try to repair things, try this: find an aluminum soda can, a pair of scissors or tin snips, a the correctly sized C-clamps or O-clamps.

Cut the ends off the soda with the scissors or snips and then cut down one side of the can so that you open the metal up. See you much of the rotted pipe is available on both sides to work with. If you're in luck, you will have several inches of good pipe on either side of the break and you can trim the aluminum can down to the size you need.

Next fold the can into a metal tube that is slightly larger than the piping you will be working with and grab either a C-clamp and properly sized wrench (usually 7/16s) and snug the C-clamp to one side of the break. Repeat the same on the end of the break and everything is fixed. You can also snug an O-clamp down on the can to hold it in place on either side.

You may find you will have to repeat this in multiple places if the breaks and rotting pipe are widespread, but this is the safest way to do things so that you will not only keep the engine's back pressure as close to normal as possible (a very important item given today's engine tolerances). And, you will keep engine gases out of the passenger compartment which can sneak in as the rope that has been advocated elsewhere loosens or burns up.

This is only a temporary fix, one that you should remedy as quickly as possible with the proper parts.
You can find the parts you need at parts outlets, such as at http://autozone.com/

Source: More than 30-years as author of a weekly how-to column for newspaper readers with a readership of more than 1 million. Automotion.com