A diesel in winter: glow plugs, the DPF and the fuel
A diesel has its own winter rules. Here is what is normal and what should not be put off.
A diesel behaves differently from a petrol engine in winter, and half the «faults» turn out to be normal operation in the cold.
This is normal
A long start after a frosty night. The glow plugs heat the chamber for a few seconds — that is what the glow symbol on the dashboard is about. Cranking before it goes out is pointless.
White vapour for the first minutes. As on a petrol engine, that is condensation.
The fan roaring while parked. A particulate filter burn-off is running, and in winter it starts more often: short trips do not let the filter warm up.
Higher consumption. Warm-up takes longer, and a cold diesel is fed more fuel.
This is not normal
The glow symbol flashes or stays on after starting. That is a glow circuit code, and in winter it turns into a no-start.
The starter spins briskly but the engine will not catch at all. In frost the first thought is the fuel: summer diesel waxes up and stops passing through the filter. Getting the car somewhere warm is the cheapest solution.
Power gone, the fan howling constantly. The filter is clogged and the burn-off never finishes.
The temperature gauge does not rise at all. A diesel has little spare heat, but operating temperature is still mandatory: look at the thermostat.
What to check before the frost
- The glow plugs. One dead plug goes unnoticed in summer; in winter it is a no-start.
- The battery. A diesel needs more starting current, and it is worth checking before the first cold snap.
- The fuel filter. A clogged one waxes up first.
- Stored codes. Summer trifles become winter failures.
