What happens if you put petrol in a Diesel engine?

obi_waynne

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I know it will go bang and break but I was wondering if anyone knows the specifics of damage done. Has it happened to you? How much did it cost to put right.
 
As far as I know, Diesel engines are a much larger compression ratio than a petrol. So petrol, which is considerably more volatile, is going to go BANG and the engines going to completely crap itself and fall apart.

As for what exactly happens, I can only assume all the components cant take that sort of pressure and various bits will snap/bend/break.

Best thing to do if you put Diesel in is not turn the ignition, but call AA or something, and get them to drain the tank. It'll only cost upto a few hundred quid, rather than grands.
 
Most IDI cars without turbos will stand up to 30% petrol mixed with diesel. Before the days of winter diesel it was common to add 5-10% to keep the diesel from turning to wax.

Modern diesels - DON'T DO THIS. You'll trash the high pressure pump because petrol is nowehere near as lubricating as diesel.

Definitely don't start it.
 
suggestion about petrol in deisel engine, e-mail topgear to do a mad experiment and get the results for us drivers of dervs because anybody can make a mistake if they are colour blind and dislectic. the engine will probaly have nervous break down and fall to bits. ha ha
 
It would be an interesting episode. I think Diesel in a Petrol engine would make for better viewing - it would be like a smoke machine :LOL:
 
id forgotten about time thread

wifes mate put about 7 ltrs of petrol in her clio by accident, she had been driving her brothers car for the last couple of days, she necked it with diesel and ran without any issues that was last week.
 
Would the petrol float in the tank over the diesel? Could be a whole lotta trouble brewing!
 
Would the petrol float in the tank over the diesel? Could be a whole lotta trouble brewing!


Thats a good guess. Would part of it maybe dilute every time you fill it? Cos, if so, you'd have to refill at say, half a tank, to keep the petrol from reaching.
 
ooh, i would love to see a petrol engine go bang due to not putting in the right petrol. so long as its not my car.
would be quite cool seeing jeremy clarksons hate for diesel. he probably would love to do it.
Enjoi
 
my mom fill our old land rover discovery TD5 full of petrol
whatever you've seen on the tele or heard on the radio is rubbish...
all that happens is that your engine cuts out because petrol doesn't burn as slow and diesel so won't work well...
all we did was drain the fuel tank (which means i had loads of mouthfuls of petrol YUK!) and drain as much as you can out the system
and fill with diesel and you just have to run the rest out it out....
There wil lots of coughs and spluttering and lots and lots and lots and lots and lots of blue/white smoke but eventually it goes and everything then is fine....
 
High injection pressure diesels can be completely killed by petrol even at very small dilutions. Petrol strips all the lubricity of the diesel fuel from pumps and injectors which leads to their rapid demise.

I would suggest that you don't even try to start a modern diesel if there's ANY petrol in the tank at all.
 
She got about 5 miles before it cut out but we jsut did all that as described before adn it's worked fine (we've got the new discovery 3 now though with the TDV6 hasvn't done it in that one)

and I've just thought then if petrol in a diesel in engine is worse than putting diesel in a petrol engine why is it that a diesel filler pump nozzole won't fit in a petrol car and a petrol one can fit in a diesels? Surely that has something to do it
(this applies to UK petrol stations not sure on the rest of the world)
 
and I've just thought then if petrol in a diesel in engine is worse than putting diesel in a petrol engine why is it that a diesel filler pump nozzole won't fit in a petrol car and a petrol one can fit in a diesels? Surely that has something to do it
(this applies to UK petrol stations not sure on the rest of the world)

umm.... it does.. someone i know put in 10 litres of diesel into his 106 then to water it down he put another 10 of petrol in it. it ran.. but chucked out LOADS of smoke an had a lot of power down
 
umm.... it does.. someone i know put in 10 litres of diesel into his 106 then to water it down he put another 10 of petrol in it. it ran.. but chucked out LOADS of smoke an had a lot of power down
don't know which petrol station he went to then....lol
 
in kent there all the same... dont really look at diesel pumps much part from to fill up my mates car for him a couple of times but ive never noticed any difference in shape to petrol.
 
put £20 of petrol in my citroen zxtd a couple of weeks ago topped it up with £40 of diesel and apart from being a bit down on power it drove fine, didn't like to start when warm though, since then it's had another £30 worth of diesel and its back to normal, starts first time
 
I put 14 pence of diesel in My mothers passat which is the 2006 tdi 170, realised just as i was putting it in. put about 20 quid of diesel in straight after and it ran fine to this day, although that was only 14 pence lol.
 
14 p (of petrol I presume) would be about a gnats crotchet at todays prices. I bet you were cursing yourself. Did you have to pay in 2 batches 14p and then £638 for the Diesel?
 
14 p (of petrol I presume) would be about a gnats crotchet at todays prices. I bet you were cursing yourself. Did you have to pay in 2 batches 14p and then £638 for the Diesel?

lol. yeah i did i looked like a complete loser. went in and payed for 14p in exact change then put diesel in. :embarrest::embarrest:
 
i dont know exactly what happenes,as i never had a diesel motor but i put diesel in my type r civic before,when i realized i had put 15 euros of it in,bollo;s,so i put another 15 petrol in and drove so slow i was almost stopped never did any damage.a fella told me if anything it would clean my engeine,or was i lucky??
 
i did it last yr. filled to brim with petrol on xmas eve drove home from local petrol station approx 800 metres car started misfiring as i got it on drive when i tried to start it wouldnt start realised wot i had done cost me £80 to have petrol drained and the cost of the petrol did i feel stupid
 
i did it last yr. filled to brim with petrol on xmas eve drove home from local petrol station approx 800 metres car started misfiring as i got it on drive when i tried to start it wouldnt start realised wot i had done cost me £80 to have petrol drained and the cost of the petrol did i feel stupid didnt do my engine any harm
 
That cant have helped your MPG at the time it sounds like you were lucky though for it not to do any harm. Was this in the Astra?
 
Am I right in thinking that an old bodge to get your old smokey derv through it's Mot was to mix some petrol in, to reduce the emmisions?
Would't suggest it with modern engines though :shock:
 
yes was the astra the guy who emptied put some petrol in it and got it running for me
he actually siad he does loads and its very rare that it does any damage
 
SOme people have been lucky and got away with this. Others have been hit with massive bills for all the injectors and a high pressure pump.

Think I fell into the 'lucky' category. Topped my Citroen C4 2.0 tdi with about 20% petrol (I checked later - this is the one local garage where ALL the hoses are black!), drove from west London to Swindon before the car objected. Pollution fault light came on and put car into 'limp home' mode (just as well it did really!). AA guy cleared the fault via the OBD port but didn't suspect the wrong fuel, but the condition came back 10 miles from Hereford. It wasn't till I got to where I was going that I spotted the till receipt! Booked it into nearest Citroen dealer and had it drained, with a change of fuel filter.

No lasting problems and that was 15,000 miles ago, although I sold it last week. Just wait for the fuel pump to crap out now!;)
 
Ditto that. You are a lucky driver. Don't suppose you mentioned it to the new owner? ;)

Hang on I've just bought a C4 2.0 Tdi from a guy in West London with a pencil moustache! :lol:
 
That's fair enough. Dealers have a duty of care that's a bit more formal than is required of a private seller. They'll check it over thoroughly with any luck. Additionally, if the pump does fail they have access to labour and parts at trade prices so it's not likely to be so costly to fix anyway.

I would advise you don't make the mistake with the Leon though. The 2.0 units are common rail and the pressures are HIGH. Any loss of boundary lubrication in the pump, such as caused by dilution of diesel fuel with petrol will wreck it pretty quickly.
 
if you fill up with the wrong fuel, for example you put petrol in a diesel.

IF you have locked the car and gone to pay for it, DO NOT unlock the car, you can cause damage by unlocking it.

this is becuase diesel engines used to take a while to turn on, that same time is still there it just starts when you unlock the car now so the pump can turn on even if you unlock it.
 
Good point that chrisjacks. Some older cars don't prime the pump until the key goes in the ignition. It pays to listen carefully as you unlock the car to see which yours does!
 

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