“The car sounds funny now.”
Ever heard that one before? You perform a repair, and the customer returns shortly thereafter with complaints or concerns about rattling noises under a vehicle or an engine that seems to run much louder. Your first thoughts lean towards exhaust problems. The situation quickly turns difficult because the customer suspects the problem is collision-related, which it could be. The customer also wants you to solve the problem now.
You have a big problem on your hands – namely, determining who is going to pay for this work. There’s no way an insurer will pick up the tab if the insurer isn’t absolutely convinced the problem is related to the collision. That can be difficult if you’re dealing with an older car whose exhaust may already have been damaged by corrosion or through normal wear and tear. Since your shop and the adjuster already have looked at the vehicle, there’s a very good chance the insurer will balk at paying for more repairs. When that happens, you’re either going to have to take care of this work yourself or be stuck with an unhappy customer who will take the vehicle elsewhere and never come to you for repairs again.
While considering those options, think of this. This entire ugly scenario could have and should have been avoided in the first place.
Several months ago, ABRN examined a comparable issue involving customers returning with suspension issues (see .) In these cases, shops similarly risk losing money and customers over repair problems that don’t seem to turn up until after a vehicle has left their property.
The solution for both areas is the same. Spend a little extra time investigating and diagnosing problems with these systems the first time you work on a vehicle. There’s a great chance you’ll spot potential or existing problems then. Not only will this head off customer come backs, it’s a great way to capture this work and put some extra money in your coffers.
Note: This article will focus on exhaust problems that can be linked to collisions or that involve repairing damaged or deteriorated parts that can be spotted during a basic inspection. Problems related to emissions or more sophisticated exhaust issues will not be discussed here.
Inspection directions
The best time to begin looking for suspension issues is during the estimate. Important here is that exhaust problems often are hidden. Though you may feel like dismissing them in vehicle with relatively light hits, never make this mistake. Take the extra time to put the vehicle on a lift and perform a proper inspection.
This means working gradually from the front of the vehicle to the rear and searching for damage or deterioration to all of the parts that make up the exhaust. This includes all the pipes, brackets, hangers, clamps, resonators, joints, seals and the muffler.
A proper inspection involves the right tools. Here, you’ll need five: Proper lighting, a metal tool such as a small ball peen hammer, a rubber mallet and finally your eyes and ears.
Working towards the rear of the vehicle, tap on each of the exhaust’s parts. Check that each resonates with a solid sound and without any rattling.
Perform a visual inspection at each part and check for damages. Look for any “excessive” metal flaking or excessive deterioration that may be resulting in leaks. Check for any binding of components or contact with vehicle undercarriage.
Make sure that all the parts fit tightly. No part on the exhaust should be loose.
Also, look for proper parts alignment since alignment is critical for exhaust performance. None of the mounting hardware should show signs of excess pull or stress.
Once you’ve finished at the tail pipe, lower the vehicle. If the vehicle is in running condition (or when it can run), start the engine and raise the vehicle again. Look for vibration and any excessive movement.
Listen for excessive noise or odd noises.
Turn the vehicle off, and examine the catalytic converter. Caution: The converter may be hot. Perform this examination while wearing heat resistant gloves.
Put away your ball peen hammer (or similar tool) and use a rubber mallet to lightly tap the converter. All you should hear is a solid thump. If the tapping produces any rattling noises, the substrate in the converter may have been damaged. Make sure these noises are emanating from the converter and not from any other loose exhaust components.
If the noises are located in the converter, check further for any broken-up substrate in the pipes and muffler. If the converter is damaged, it will need replaced (more on this later.)
When the vehicle is drivable, continue the exhaust inspection with a road test. Listen again for any unusual sounds or odd noises from the exhaust. Roll up the windows and note any exhaust odors that may be leaking into the vehicle.
That’s it. A proper inspection, which shouldn’t take any longer than 30 minutes, will uncover the vast majority of existing or potential exhaust issues. By noting them at this point in the repair, you’ll have plenty of time to notify the insurer and the customer. You’ll also have paved the way for your shop taking care of any work.
Quick hits: A repair for every problem
After the inspection, your techs will need to determine the right course of action to handle any repair issues. This is where you’ll turn to OEM and other repair information to produce a proper diagnosis and the correct repair steps. Fortunately, most exhaust problems you’ll be seeing should be fairly easy to diagnose, especially following a proper inspection. Further, the repairs you’ll need to perform won’t involve a lot of complicated work (yet another reason why you don’t want to lose this work to another shop).
Consider these common exhaust issues and their most likely sources.
Problem: External exhaust rattle
Likely source: Heat shield weld failure
Rust and heat cycling can cause the welds on the heat shield to fail, as can collision damage. Repair with new welds or install exhaust clamps to hold the pipe in place.
Problem: Exhaust hangs too low (may scrape speed bumps)
Likely source: Missing, damaged or worn hangers/rubber insulators
You should note this problem during the inspection. Replace all damaged or worn parts. If you need to install insulators, make sure they hang straight and have no fore or aft tension on them.
Problem: Loud exhaust tone
Likely source: Internal muffler failure
Obviously, this is a case where you would replace the muffler. Note that some aftermarket mufflers may produce exhaust noise louder than their OEM counterparts. When discussing replacement options with the customer, be sure to point this out. Better still, become familiar with aftermarket mufflers you might be installing.
Problem: Reverberating noise in passenger compartment or a droning sound when speed is maintained
Likely source: Internal muffler failure
Note previous instructions on replacing mufflers.
Problem: Tinny or ringing sound from exhaust components, most notably at low speeds.
Likely source: New exhaust system or parts
Oftentimes, new exhaust systems will produce this sound. It’s perfectly normal and eventually will diminish once carbon forms on the inside of the pipes. Advise the customer to drive the vehicle normally.
Converter concerns
If the catalytic converter needs replaced, you’ll need to keep a few things in mind.
First, you need to make sure the problems that led to its failure don’t similarly ruin the replacement. Even if a collision caused the damage to this part, don’t dismiss other existing problems with the exhaust system that could do harm to a new converter. Therefore, before installing the replacement, take the following steps:
Step 1: Retrieve all PCM (Powertrain Control Module) trouble codes and perform required repair procedures for any stored codes.
Step 2: Address any exhaust system leaks.
Step 3: Examine the O2 sensor operation to ensure vehicle is in fuel control.
Step 4: Evaluate the mechanical condition of the engine - including running a cooling system pressure test. Doing so helps prevent future contamination of the replacement converter.
Next, you need to locate the right converter replacement, which can be something of a challenge if you’re using an aftermarket version.
To determine which converter to use, you’ll need the vehicle’s Emissions Control Information Label. It’s typically located in a visible area of the engine compartment, for example, strut tower, the hood underside, radiator support, fan shroud or firewall. If the label is missing, you’ll need to contact a new car dealer for a replacement.
The label indicates the vehicle’s emission’s certification. For example, a vehicle is a California Emissions Certified model if the Emissions Control Label references: “California,” “ARB,” “CARB” or “50-State.”
Finally, you’ll need the Engine Family Number (EFN), which also is on the label. This information is critical if you work in a state that mandates replacement converters be CARB-compliant.
Emissions information is critical when looking up parts in the application catalog, both to ensure proper fit and to ensure you adhere to state-mandated aftermarket replacement converter regulations. For example, California mandates that aftermarket replacement converters for any vehicle licensed in the state must be CARB-compliant. In New York, only vehicles made in model years 1993, 1994, 1996 and newer, must use converters that are CARB-compliant.
On the subject of aftermarket exhaust parts, you’ll need to keep an eye out for the numerous aftermarket exhausts on the market. Customers who invest in these systems will be particularly mindful of any changes to them following a crash. These changes can be esthetic (dented or scratched chrome) or loss of power or performance. Spend some time at the beginning of the repairing talking to these folks to learn why they made the investment and what their expectations will be when they get their vehicles back.
As with any exhaust work, time wisely invested up front will be rewarded when the work is done and you get to send a happy customer on his or her way.
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