by Visibility items are among the most common MOT failures and among the cheapest to put right. They are also the ones owners most often defer, because a smearing wiper is an irritation rather than a breakdown. On a van doing motorway miles in winter, poor visibility is a genuine safety matter.
Windscreen damage
What actually fails an MOT
Damage is assessed by size and by where it sits. A defined zone directly in the driver line of vision, swept by the wipers, has a stricter limit than the rest of the swept area. Damage larger than the permitted size in that central zone is a failure; the same damage further out to the side may pass.
The practical implication is that a small chip in front of the driver matters more than a larger one near the passenger side, and that position is as important as size when judging whether to act.
Why chips spread
A chip is a stress point in a sheet of glass that flexes constantly and experiences large temperature swings. Cold nights, hot demisters, body flex over potholes and door slams all work on it. Chips very rarely stay the same size indefinitely.
The practical advice follows: repair chips early. A repair is quick, comparatively cheap, and many UK insurers cover windscreen repair with no excess or a small one, often without affecting no claims. A crack that has spread means full replacement, which costs considerably more.
Replacement considerations on a modern van
If your van has a camera behind the windscreen for lane assist, autonomous emergency braking or similar, the system generally requires recalibration after windscreen replacement. This is not optional: an uncalibrated camera can misjudge, and the systems that depend on it are safety features. Confirm the fitter includes recalibration, as it is a common gap in cheaper quotes.
Wiper faults
Smearing
Usually perished blades, but not always. Also caused by a film of polish, wax, traffic film or silicone on the glass, or by contamination on the blade itself. Before buying blades, clean the glass thoroughly with a proper glass cleaner and wipe the blade edge with a damp cloth. Frequently that resolves it.
Juddering or chattering
Blade angle relative to the glass, a stiff or worn linkage, or a hardened blade rubber. Sometimes caused by an arm that has been bent slightly, changing the contact angle.
Missing large areas or lifting at speed
Worn blade, a weak wiper arm spring, or a blade that is the wrong length or profile for the van. On a tall van at motorway speed, air pressure lifting the blade is a real effect.
Wipers slow, stop in the wrong place, or work only on one speed
Points at the motor, the park switch inside it, or the wiper relay. Wipers that do not park correctly are usually a park switch fault.
Wipers do not move but the motor hums
The linkage has failed or a spindle has seized. Common on older vans, where the linkage joints wear or corrode. Continuing to operate it can burn out the motor.
One wiper moves, the other does not
A linkage joint has come apart or a spindle nut has loosened.
Washer faults
No spray at all
Check in this order: fluid level first, since it is the most common cause and the easiest to overlook. Then listen for the pump running when the stalk is operated. If the pump runs, the blockage is downstream in the pipes or jets. If it does not, look at the fuse, the switch, the wiring and the pump itself.
Weak or misdirected spray
Blocked jets, which can usually be cleared carefully with a fine pin, or aiming that has drifted. Many jets are adjustable with a pin in the outlet. Aim so the spray lands in the upper part of the swept area at driving speed, not at the bottom of the screen.
Pump runs but no fluid
Air lock, a split or disconnected pipe, or a blocked filter on the pump pickup. Check the pipe run, particularly where it passes through the bulkhead or bonnet hinge area, which is where it chafes.
Works in summer, fails in winter
Frozen fluid or frozen jets. Plain water freezes and can split the reservoir or pump, which is why a proper screenwash concentrate at the correct winter dilution matters. It is also worth remembering that washers are an MOT item and a frozen system on test day is still a failure.
Diagnostic sequence for a dead washer
- Check the fluid level. Obvious, frequently the answer.
- Listen for the pump with the ignition on and someone operating the stalk.
- Check the fuse if the pump is silent.
- Check for voltage at the pump when operated. Voltage present and no sound means a failed pump.
- Trace the pipework if the pump runs, looking for splits, disconnections and kinks.
- Clear the jets with a fine pin and re-aim.
Indicative UK costs
Broad context only. Wiper blades are inexpensive, typically ten to thirty pounds a pair for a van. A washer pump is usually a modest part. A wiper linkage or motor commonly runs into the low hundreds fitted. Windscreen chip repair is frequently covered by insurance with little or no excess; full replacement runs into the hundreds and more where camera recalibration is required. Get quotes.
Common mistakes
- Buying blades before cleaning the glass. Contamination causes a lot of smearing.
- Ignoring a small chip. Repair is cheap; a spread crack is not.
- Using plain water as screenwash. Freezes, and offers no cleaning power against traffic film.
- Running wipers on a dry or icy screen. Destroys blades quickly and can strain the linkage.
- Forcing frozen wipers. Tears the rubber and can damage the motor or linkage.
- Skipping camera recalibration after a windscreen replacement. Compromises driver assistance systems.
- Overlooking the rear wiper where fitted. It is an MOT item too on vehicles required to have one.
When to stop and get help
Do not drive with significantly impaired forward vision. Get help if the wiper motor hums without moving the blades, as continued operation burns it out, or if a crack is spreading across the screen. Windscreen replacement on a van with camera-based driver assistance should be done by a fitter who can recalibrate.
Prevention
Replace blades before they perish, typically at least annually. Clean the glass properly, not just with washer fluid. Use screenwash at the correct winter dilution. Lift the blades or use a screen cover in freezing weather. Clear ice before switching the wipers on. Repair chips promptly.
Frequently asked questions
Will a small chip fail the MOT?
It depends on size and position. Damage in the zone directly in the driver line of vision has a stricter limit than elsewhere on the swept area.
Why do my new wipers still smear?
Usually contamination on the glass. Clean thoroughly with a proper glass cleaner and wipe the blade edges before assuming the blades are faulty.
Do I need windscreen camera recalibration?
If your van has a camera behind the screen for driver assistance, yes. Confirm it is included in any replacement quote.
Can I use washing up liquid in the washer bottle?
No. It foams excessively, can damage paint and seals, and offers no freeze protection.
This guide is general information for UK van owners, not vehicle-specific repair instructions. Procedures, tolerances and component layouts vary by engine code and model year. Confirm any figures against your VIN and manufacturer workshop information, and see our Disclaimer before carrying out any work.
