It probably didn’t go unnoticed but a few days ago was Halloween. How many eggs did you get thrown at your windows? I got none, since I live in a flat and little brats can’t throw that high up! But in all seriousness, none were thrown and I didn’t get any trick or treat-ers either. This is just as well since I didn’t buy any sweets. This is not to say that I don’t like Halloween though, this weekend myself and friends are having a fancy dress Halloween party to celebrate. Pictures of our costumes will follow another day (maybe!) as they’ve all been kept secret until the party.

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One of the other more interesting parts of the week occurred tonight on the way home from work. Traffic jams are fairly frequent at the moment as people suddenly suffer the inability to drive in the dark with daylight saving time ending last weekend. However this traffic jam was caused by a rare occurrence. Someone in a white van (a guy I’ll presume) suffered a horrible failure somewhere in his engine and suddenly found it providing power even when his foot was off the throttle pedal. He managed to pull over safely but it was already too late.

This was the point I came up to the traffic jam wondering what was causing it. A minute or two later as the traffic crept forward I noticed smoke coming from the hard shoulder. Oh dear I was thinking to myself, a car is on fire. I couldn’t see it clearly at this point, all I saw was smoke. A minute later as I got closer I saw it was this van with thick black/gray smoke pouring out of the back. I immediately knew what had happened. Something in the engine, either the turbo seals, or other engine oil related item had failed and the engine was now what is called “running away”, consuming oil instead of fuel.

This is what happens and what it looks and sounds like when a diesel engine “runs away”:

In this condition, turning off the ignition does nothing – the engine is running on pure compression and self feeding oil into itself. The only way to stop this is to put the vehicle in a high gear, foot as hard as you can on the brakes and release the clutch. The engine will stall and the engine is saved. Well, I say the engine is saved, but only if you do this straight away. In a “run away” condition the engine will be “over-revving” or “red-lining”. If you have a tachometer this is where your engine revs into the red zone. If you do this for more than a few seconds the engine is outside of it’s safety limits and things start to go wrong quickly. The valves will start smashing into the pistons, the engine will rapidly overheat and seals will get blown. If you manage to stall the engine quickly enough you’ll limit the damage and save most if not all of the engine. If you don’t, you’ll be looking at a new engine or at the least new valves. It’s worth noting this can happen to any engine, but primarily happens to diesels because of their huge compression compared to petrol engines. Turbo engines suffer more often too because turbo seal failure is fairly common.

Anyway the point of this story was that the driver did not know what was happening or how to stop it. He let the engine run away for at least a few minutes. I’d already passed so I don’t know the outcome but I can only imagine that engine is now completely toast. As I went past the smoke was so thick I could barely see the car in front and the noise coming from the engine was saddening. As a diesel engine lover you get to know what a healthy engine sounds like and that was not a  healthy diesel at all! So please, if you own a diesel or know someone who does, pass on the advice above and make sure they know to use it if it ever happens to them. It could be difference between a new engine or just a cheap repair.