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Exhausts and Catalytic Converter Check & Repair

Your car or van exhaust is one of the most important aspects of your vehicle. If you have any issues with your exhaust, this can result in a number of different problems which could lead to reduced fuel efficiency, increased exhaust and engine noise and also an increase in the harmful gases pumped into the environment.

Exhaust check

At National Tyres and Autocare we currently stock over 15,000 exhaust parts. We offer a FREE exhaust check if you are experiencing problems with your exhaust. A free exhaust check can be booked in at your local National Tyres and Autocare branch by clicking the ‘Book an Appointment’ button at the top of this page.

Identify Exhaust Problems

If you notice any of the following you should have your exhaust checked by a National expert to find out whether any components need replacing;

If you notice an increase in the noise of your engine, this could be due to an issue with the car exhaust. This could mean that there may be a problem with the catalytic converter, or this may be a sign of a leak from your exhaust. If this is the case, we would urge you to get booked in at your local National Tyres and Autocare branch as the longer you ignore this engine noise, the more severe the problem may become.

Another sign of an issue with your exhaust would be if you notice a decrease in the acceleration of either your car or van. An exhaust leak may be a sign if you notice this lack of power. This particular concern would result in your vehicle’s performance being negatively affected, meaning you will no longer be able to accelerate as quickly as previously nor will get the same power when you accelerate.

If you notice that you are no longer getting the same MPG from your vehicle as you have been previously, this could point to an issue with your vehicle’s exhaust. If you have a problem with your exhaust, this can potentially reduce your fuel efficiency, meaning that you will be spending more money on fuel, as your engine will be doing extra work to ensure you are able to continue to drive your vehicle.

If you notice a burning smell coming from your engine, we would advise that you urgently get yourself booked into your local National Tyres and Autocare branch. This burning smell could be the result of an oil leak within your engine, that may be dripping down onto the exhaust pipe, causing a strong burning smell which would need to be checked.

If you notice that your exhaust pipe is disfigured in any way, then this would need to be urgently looked at to ensure that no serious issues occur from this.

A rattling noise may indicate loose brackets holding the system in place.

A roaring noise could be a potential problem with the silencer.

This could be a sign that the silencer or one of the pipes is leaking.

This could indicate a fault in the engine which is putting burnt oil into the exhaust system and resulting in blue smoke.

White smoke when first started is normal. If it continues, this could be due to an internal coolant leak and the white smoke is the result of burning antifreeze. This could also mean that there may potentially be an issue with the vehicle’s head gasket.

Rust or corrosion on the pipe as well as cracks, especially where the pipes connect could indicate a problem.

Free Exhaust Check

At National Tyres and Autocare, we provide a FREE exhaust check at a branch local to you. During this exhaust check, our highly trained staff will check whether there are any issues with the exhaust system, including checking the catalytic converter. During this exhaust check, our branch staff will be able to advise if any there are any concerns and if are parts need to be replaced. To book a free exhaust check, please click on the link at the top of this page to add an exhaust check to your basket.

 

Express, Interim or Full Service

At National Tyres and Autocare, we now offer three different tiers of servicing. An Express Service, an Interim Service and a Full Service. During all of these levels of servicing, our branch staff will check the exhaust system and mountings.

Related: Servicing Packages

 

Exhaust Guarantees

We offer a 3-year unlimited mileage guarantee on exhausts. We will offer a guaranteed free repair or replacement as long as you own the car for which the parts were purchased and fitted. This includes normal wear and tear and manufacturer defects when all of the parts were fitted by National Tyres and Autocare. Please read the terms and conditions below to find out more about National Tyres and Autocare’s exhaust guarantee procedure.

Any full or short assembly system including a catalytic converter is covered. All products supplied and fitted by National Tyres and Autocare are guaranteed against faulty workmanship or manufacturing defects. The original cash sales invoice is required as proof of purchase before any guarantee work can be carried out. Please attach this guarantee to your original cash sales invoice and keep them in a safe place. Prior to making any claim, please refer to the following:

  1. National Tyres and Autocare will either repair or replace the defective part on the vehicle free of charge (subject to the conditions of the guarantee).
  2. Parts that fail due to criminal or malicious damage, vandalism, improper use, fire, theft, use in competitive sport, road accident, repair by another garage and accidental impact damage are all excluded.
  3. 3-year guarantee applies to full and short exhaust systems or 2 years on individual parts.
  4. If a part is removed from the vehicle by another company or individual the guarantee does not apply.
  5. Guarantees are not transferable.
  6. All guarantees apply from the date of original purchase.
  7. If suitable replacement parts are no longer available, National reserve the right to discharge any obligation by refunding the amount originally paid for the part(s).
  8. Guarantee applies to complete full or short assembly systems including catalytic converters.
  9. The guarantee applies to private motorists only and excludes taxis, mini cabs, driving school vehicles and any vehicles used for business or commercial purposes.
  10. National Tyres and Autocare guarantees are in addition to, and do not detract from your statutory rights.

 

Exhausts Price Promise

At National Tyres and Autocare, we regularly check our prices against our competitors. To ensure that we are never beaten on price, we offer a price promise for our customers. If you find the same product at a cheaper price than you have received at your local National branch within seven days of your purchase, we will beat the competitor's written quotation.

Related: Price Promise

 

How does an exhaust system work?

The exhaust is made up of numerous mechanisms including the exhaust manifold, the catalytic converter, silencer and the exhaust pipe. To ensure that the exhaust system works efficiently, all of these areas need to functioning correctly. The exhaust manifold will capture the gases from the head of the cylinder in the engine.

The exhaust manifold will then push these gases through the engine cylinders and then they are released through the exhaust pipe. The exhaust system consists of a number of pipes, which come in varied sizes. Each of these pipes connects to one another, and each is shaped to fit an exact part on the underside of the vehicle.

Each pipe helps move the gases to the back of the vehicle, the catalytic converter then helps convert the harmful gases into inert gases, the silencer will help minimise noise levels and the exhaust controls the output of these gases. The fumes will then exit the vehicle from the tail pipe. This ensures that the gases are pushed away and out of the vehicle.

 

What are the different parts of an exhaust system?

An exhaust system has no moving parts. The function of an exhaust system and its placement on either your car or van means it is a component that works extremely hard.

Toxic wastes within the exhaust system can lead to corrosion and rust. This negatively affects the metal within the exhaust system. This can lead to your exhaust becoming extremely noisy and could also lead to other potentially dangerous issues. If the noise levels of your exhausts are higher than the legal amount, this will lead to a fine.

In addition, a failed exhaust can cause leakages into the exhaust system. This can become a risk to the driver and passengers, causing a number of negative and dangerous side effects. Here are the key components of an exhaust system.

The tail pipe allows free exit of the exhaust gases into the atmosphere.

The silencer is specially designed to decrease sound waves created by the engine and reduce this noise to an acceptable level, both legally and environmentally. It is possible to have more than one silencers fitted to your vehicle.

The job of a catalytic converter or CAT, is to extinguish any harmful and dangerous gases before they are removed from the tail pipe and into the atmosphere. The catalytic converter converts these harmful gases into environmentally friendly before they leave the exhaust system. If your catalytic converter is faulty, this can lead to a fine and cause black smoke to come from your vehicle. The lifespan of a catalytic converter depends on your driving style and frequency of driving.

The exhaust manifold collects gases from a number of cylinders within the engine. The exhaust manifold then pushes these gases through the exhaust system.

 

What can cause an exhaust system fault?

At the end of a journey when the engine is switched off, exhaust gases remaining in the silencer system condense with cooling to form a condensate. If the process is repeated and the condensate accumulates, this can accelerate the internal corrosion.

The gap in temperature between the car and the driving environment can also increase the likelihood of corrosion.

Mud, water and salt coming from the road and being projected on the exhaust system accelerate external corrosion. Also, any projectiles from the road (stones, unknown items, etc..) could cause a hole in the boxes or damage the mountings.



How does an exhaust affect performance?

An exhaust which is functioning correctly and has no problems will improve performance and your overall driving experience. The exhaust directs fumes and gases away from the passengers and out of the tail pipe at the back of the car. If your exhaust has issues which would hinder this process, this would be extremely dangerous for the passengers inside the car. The exhaust system also improves internal and external noises levels.


Frequently Asked Questions

The job of a silencer is to help reduce the noise levels produced by the engine during the process of internal combustion. A silencer will help minimise internal and external noise levels, while the exhaust will control the output of the gas and the catalytic converter will ensure that the harmful gases are converted.

The main job of a catalytic converter is to convert harmful gases from the engine and converted them into friendly gases such as carbon dioxide. A catalytic converter can last up to 10 years, however, this will depend on your driving style and how often you drive your vehicle. If you only use your vehicle for short journeys, this will reduce the lifespan of the catalytic converter as the engine will not operate at its maximum temperature level meaning the catalytic converter will wear out more quickly.

Yes, a faulty catalytic converter can result in an MOT failure. This failure will leave you unable to drive your vehicle until this issue has been repaired. A faulty catalytic converter can result in an improper and dangerous amount of harmful emissions.

Yes. An MOT can be failed if the noise levels of your exhaust are deemed unacceptable by the MOT tester. This can signal a problem with the silencer and these will need to be repaired or replaced a vehicle to be granted with an MOT pass certificate. It is important to note, that a faulty catalytic converter can also result in an MOT failure due to an unacceptable amount of harmful gases being emitted from the vehicle.

Blue Smoke

If you notice that blue smoke is coming out of your exhaust, this could be an indication that oil from the engine may have entered into the fuel system. A burning smell may occur if this is the case. If you notice a burning smell, we advise you urgently get your vehicle booked in for an exhaust check.

Grey Smoke

If you notice that grey smoke if coming out of your exhaust, this could be a sign of an oil leak. It is important to note that if you own an automatic vehicle, grey smoke could also indicate that the transmission fluid may be leaking. In both of these cases, we recommend that you book in for an exhaust check at your local National Tyres and Autocare branch.

Black Smoke

If you notice black smoke coming from your exhaust, this could be a number of different issues depending on whether the vehicle is petrol or diesel. If your car is petrol, black smoke coming from the exhaust could mean that the air filter needs to be replaced as too much fuel is burning. If you think this is the case, you can book in for a FREE vehicle health safety check by clicking here. In diesel cars, if you see black smoke coming from the exhaust this could point to a problem with the particulate filter.

A particulate filter picks up soot however if this is not working correctly, this will lead to an excessive amount of soot. If this is the case, this would lead to an excess of unburnt fuel which would create black smoke. This is more common in vehicles that are only used for short journeys. To dislodge this, longer distance and motorway driving may fix the problem. However, we would still recommend booking in for an exhaust check.

Thick white smoke

If you notice thick white smoke coming from your exhaust, there may be a problem with your vehicle overheating. This mainly occurs if there are head gasket issues. White smoke can also indicate an internal coolant leak.

If we are wanting to figure out if an exhaust can increase power, firstly we need to understand the process that is taking place. When you are driving, air moves into and out of the combustion chamber. If your car’s exhaust is restricted in any way this can lead to the exhaust gasses spilling back into the combustion chamber. This results in less oxygen being available, which consequently will reduce your car’s horsepower. To ensure that your engine has more power, it is important to maximise the amount of oxygen within the combustion chamber. High-quality exhaust systems will create vacuums which will reduce the back-pressure to minimise any gasses spilling back into the combustion chamber. Due to the combustion changer now having more oxygen, horsepower will be increased and the engine will gain more power.

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Customer comments

"From start to finish, having my exhaust replaced by National was a first class experience"
Peter, Stoke


"I phoned 3 garages; National Tyres offered me the best price and replaced my exhaust within an hour (as promised)"
Christine, Cardiff


"Cheaper than anywhere else and a great service too"
Robert, Glasgow


"My exhaust was making a rattling noise.
I phoned National and received advice from a very pleasant and polite guy…and a surprisingly good price too"
Karen, Lancs


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