Petrol in a Diesel Car in Trehafod: How Worried Should You Be?
Unstarted? Then less anxious than you probably are. Until your ignition primes the pump, your starter turns, or the car is driven, petrol in a diesel tank just sits there and does nothing. Which means the honest reply to that first Trehafod query — "have I wrecked it?" — normally no. Petrol in Diesel is who to phone, with your motor kept off, and so it stays that way. Keep reading for three things: the effect petrol has inside a diesel motor, the signs of how far it has spread, and the way to make sure you never repeat it.
Petrol in a diesel: what does it do to the motor?
Diesel has two jobs on its way through an engine. Lubricating comes before burning; it does both. What keeps the surfaces inside your high-pressure pump and your injectors from grinding against one another is your diesel passing through them — they're designed to very fine clearances.
Petrol does the first task badly and the second not at all. Being less viscous than diesel, petrol strips away the lubrication a fuel system needs, leaving a pump on the mixture wearing itself. It is equally made to resist igniting under compression — the reverse of what a diesel needs — which is why you hear the knocking.
The shape of the issue is clear when you put those together. Contact doesn't do the harm — movement does. A tank with petrol in it is a fuel problem. Whatever a worn pump sheds goes on, borne by your fuel, into the injectors further along, which is why a pump that has been working on the petrol is where a mechanical fault starts.
How serious is petrol in a diesel? Four situations our technicians see around Trehafod
Filled up, and not started: nothing beats it. Just your tank has petrol in it, so the task is draining the tank and purging your system where the vehicle sits. This situation can only truly take place on a forecourt: anywhere else, your car got there by being driven.
Started for a second, or only your ignition on. Once primed, your system has drawn petrol out of that tank up to your filter and the fuel lines. That is generally still a simple job — a drain, a flush, and the fuel filter seen to.
Driven a few miles. Now the pump has spent these miles labouring on weakened fuel. Tank, lines, filter, then fresh fuel put through the entire circuit: that's the work, and the way the vehicle was driven matters as much as the miles. A school run to the local primary school is one thing. A run as far as Cardiff, under 15 miles away, is a very different task. So is any distance on the M4, under 10 miles from Trehafod, where the engine has been running hard throughout.
Driven on till it complained — clattering, smoke, an uneven idle, a soft throttle. That is your motor telling you its fuel has stopped behaving like diesel. Leave it wherever it stops: a lay-by, a side street, the verge on Bridge Street. Long-term damage is very unusual if a vehicle is pulled over early, and the drain and flush that still come first sort it out.
Myths Trehafod motorists hear about petrol in a diesel
Myth: "Fill it the rest of the way with diesel and it'll be fine." It will not. Nothing is removed by topping up — you're left with a fuller tank, still the same mixture. The idea behind the advice — that diesel fuel systems tolerate petrol by percentage — is wrong.
Myth: a modern diesel copes with a bit of petrol. Rather, the opposite. Protection matters more on newer diesels, not less, because their fuel runs through finer components at higher pressure.
Myth: "If it starts and drives, there is no harm done." This is the one that fools drivers. The driver of a petrol motor fed diesel usually has no choice but to stop, because it will not run, and the damage stops with them. Nothing seems to have happened when a diesel fed petrol fires up, ticks over and drives away, which it usually does; meanwhile the pump wears. Running doesn't mean fine.
"A drop of two-stroke oil and drive it home" — a myth, taken from a fix from years ago, for a distinct problem. It does not put back what petrol has thinned, and the petrol is still in that tank afterwards.
"Drain it yourself and you are sorted" — a myth, since after it's been running some petrol sits in the filter and lines, ready to go straight back through your pump on your next start. And, a can of petrol drained at the roadside is truly risky.
How petrol ends up: petrol in a diesel
It's rarely carelessness, and no one does it on purpose. A diesel nozzle mostly will not fit a petrol vehicle, yet the smaller petrol nozzle goes into the filler of a diesel almost without resistance — so forecourts make this one error easy, and only in one direction.
Routine and the car getting out of step is when it happens. Any motor that is new to you — hired, on loan as a courtesy car, or just bought. Two motors on one driveway, one petrol, one diesel. A well-known forecourt with the pumps in a different order. Fuelling up in a rush en route to the nearest station, with a train to catch. A new-to-you diesel Renault Megane, its first fuelling, and a driver used to petrol: precisely when it occurs. Add a back seat full of kids, a phone call or rain, and the hand takes over.
Next time you fill up around Trehafod: avoiding petrol in a diesel
- A green handle for unleaded and black for diesel is normal in the UK — yet not on each forecourt. Trust the label on the petrol pump, not the colour.
- Check your filler flap. Many cars state the fuel inside the flap or on the cap. Look at it on the first fill in a vehicle you do not know.
- A coloured fob or a sticker on your diesel's key does more than any amount of meaning to remember, in a house with one of each.
- Before the nozzle comes off the pump the first time you fill a hired or new car, say "diesel" aloud. Silly, yes, yet it does the trick.
- Mistakes like this are straightforward to make while your mind is on something else, and so the phone goes away.
- A misfuel inhibitor helps, up to a point. Some diesels have a filler designed to reject a petrol nozzle, and add-on devices are available for motors without one. They are a backstop, not a reason to stop checking the pump.
- Stop the moment you realise. Less petrol inside your tank makes a thinner mixture. It does not change what to do next, which is still not to crank it.
Petrol already in a diesel around Trehafod? Begin here
Short and simple, then, is the order of things. Leave it unstarted, with your ignition off too. The attendants at the forecourt — whether at Texaco itself or wherever you filled up — will normally help push it clear of the petrol pump if you ask. Then phone 0333 366 0103 and tell us what was put in, about how much, and if it's run.
AdBlue, not petrol? Then say so. Corrosion and deposits, not lost lubrication, make it a different fault — Trehafod has a page just for it.
Why one petrol in a diesel job around Trehafod costs more than another
The four scenarios above are four different tasks, so no single price for this would be fair. Which of them you're in is chiefly what shifts the cost. Two things come after that: the petrol that went in as a proportion of what that tank takes, then the spot your car is in and whether a technician can get to it safely.
Ahead of any quote, not after, we ask three questions: your fuel that got in, the amount, and if it has run. That is why. A range turns into a straight figure when the replies are in.
About Trehafod
Trehafod is a small suburban area situated on the riverside in Rhondda Cynon Taf, with a mix of terraced housing and local amenities. Trehafod sits at an elevation of 74 metres, near the communities of Llwyncelyn and Hopkinstown. Trehafod is located close to the Welsh capital, with Cardiff just 12.6 miles away, and is part of the wider urban area along the river. Trehafod has a population of around 1350 residents.
Trehafod and Rhondda Cynon Taf: where our fuel drain cover reaches
Our vans answering petrol in diesel calls around Trehafod, in the CF postcode area, equally work the places around it, Llwyncelyn, Britannia and Hopkinstown among them. The vehicle does not need to move to us: we drain at a forecourt, in a supermarket car park, in a lay-by or on your own driveway.
Still at the petrol pump in Trehafod?
In that case, you could not be in a better place. Turned off it stays; then phone.