HGV exhaust pipe replacement: what to check before you order
Exhaust pipe failures on HGVs typically come down to corrosion from road salts and condensate, physical damage from ground contact or stone strikes, or cracking at stress points near flexible joints. On high-mileage vehicles, the section immediately downstream of the DPF runs hot and cool repeatedly, which weakens the pipe wall over time.
When ordering a replacement section, you need the outside diameter of the pipe, the length of the section you are replacing, and the joint type at each end. Most HGV exhaust pipes use slip-joint connections secured by saddle clamps. Measure the existing section before ordering, particularly on repaired vehicles where a non-OEM section may already be in place.
Flexible sections are used where the exhaust passes close to a body flex point or engine mount to absorb movement and vibration. These have a finite service life and are worth replacing preventively when fitting other exhaust components nearby.
Frequently Asked Questions
How do I measure the exhaust pipe diameter on my HGV?
Measure the outside diameter of the pipe at the section you are replacing, not the inside diameter. HGV exhaust pipes are specified by OD in millimetres. On slip-joint sections, measure both the male and female ends, as they will differ by the wall thickness.
What is the difference between a flexible exhaust section and a rigid pipe?
A flexible section uses a corrugated metal construction to allow axial and angular movement without cracking. It is fitted where the exhaust system is subject to engine movement or chassis flex. Rigid pipes are used on fixed sections where movement is not a design requirement.
Can I repair a cracked exhaust pipe rather than replace it?
Exhaust repair bandages and paste can seal small cracks temporarily but are not a lasting fix on a working HGV where the exhaust runs hot continuously. A cracked pipe near the DPF or SCR risks affecting aftertreatment performance and may trigger fault codes. Replacement is the reliable option.
Do exhaust pipe repairs affect DVSA annual test pass rates?
Yes. DVSA annual test inspection includes checking for exhaust leaks, excessive smoke, and insecure components. A poorly repaired or leaking exhaust pipe can result in a failure. Ensure all joints are sealed and all clamps are correctly torqued before presenting for test.
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