Periodic inspection of a diesel van: weak brakes, smoke and a perforated sill
A 2014 2.5 L diesel panel van, kerb mass 1,850 kg, is presented for its periodic inspection. The roller brake test gives front left 2,300 N, front right 1,750 N, rear left 1,050 N, rear right 980 N, and a parking brake total of 1,900 N. The inspection standard you work to requires 50% service brake efficiency, 16% parking brake efficiency and no more than 30% imbalance across an axle. The opacity meter reads 2.1 m⁻¹ against a 1.5 m⁻¹ limit for this engine. The left sill has a 120 mm perforation within 300 mm of a seatbelt anchorage and a rear suspension mounting. The customer needs the certificate today for a delivery contract, offers to pay extra, says the brakes 'pulled up straight on the way here', and asks you to test the smoke again later when the engine is properly hot.
1. Calculate the service and parking brake efficiencies and the axle imbalances, and state the pass or fail decision with reasoning.
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Service brake efficiency. Total force = 2,300 + 1,750 + 1,050 + 980 = 6,080 N. Weight = 1,850 × 9.81 = 18,149 N. Efficiency = 6,080 / 18,149 = 33.5% against the 50% required for this class. Fail, and by a wide margin - not a marginal reading a second test could rescue.
Imbalance. Front: (2,300 − 1,750) / 2,300 = 23.9%, inside 30%. Rear: (1,050 − 980) / 1,050 = 6.7%, fine. The circuits are reasonably balanced, but the whole system is weak. That pattern points to glazed or contaminated linings, a seized or restricted caliper, a weak servo, or a partially seized park-brake mechanism holding the rear brakes off their share.
Parking brake. 1,900 / 18,149 = 10.5% against 16% required; it needs 2,904 N to pass.
Decision: reject. 'It pulled up straight on the way here' describes balance, not retardation. The rear contribution of 2,030 N is only 11% of the vehicle's weight, which is far below what a loaded van needs on a wet road.
2. How do you handle the failed opacity test and the request to 'test it again when it is hot'?
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2.1 m⁻¹ against a 1.5 m⁻¹ limit is a clear fail, and on a 2014 diesel with that reading I would suspect the DPF has been removed or gutted before I suspected the injectors. Look for welding repairs on the canister, a straight pipe, a disconnected pressure-sensor pipe and a soot-free tailpipe on a diesel. Then check the air filter, boost leaks and injector correction values.
The 'test it hot' request: the procedure already requires the engine at operating temperature, so there is no legitimate warmer test that would give a different answer. A re-test is valid after a repair, or as the documented repeat the procedure permits, and the result is recorded, not negotiated. Running the vehicle twice hoping for a better number is falsifying an inspection, and the log will show two tests and one certificate.
If the DPF has been removed, the vehicle is non-compliant whatever the opacity reading says, cannot be certified, and the customer must be told the cost of restoring the emissions system before any re-test is worth booking.
3. The sill corrosion and the offer of extra payment must both be dealt with. What is your response and what do you record?
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Corrosion is the most serious of the three faults. A 120 mm perforation within 300 mm of a seatbelt anchorage or a suspension mounting is a structural rejection in any inspection manual I would work to: the anchorage can pull through under crash load and the suspension point can tear. That is a fail with no discretion, and the repair needs a welded section by a competent body shop followed by a full re-test.
On the money: refuse, and say why once, calmly. Certifying a vehicle you know to be unroadworthy is an offence, it ends the inspector's approval and the workshop's, and after a crash the first document examined is the inspection record with your name on it.
Record: the measured brake values, the opacity result and test conditions, the corrosion location and size, the customer's request for a re-test and his offer, in the job notes. Issue the fail report with the figures, give him the repair and re-test route in writing, and - given the brake result - advise recovery rather than letting him drive away.