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If you have put a quarter of a tank of unleaded in to a diesel car - is it ok to fill the rest of the tank with diesel (25% petrol and 75% diesel), or will this damage the engine?
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Bin there, done that, got the T shirt, tho not quite that much. Put in about 10 quids worth of petrol (was about 60p a litre at the time) into a diesel before I realised. Filled it up with Diesel and car ran fine. Was a Cavalier 1.7td (isuzu)
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Hi Nick,
Your car will run with petrol in it, though not designed to.
If you can, drain a gallon or two off, top up with derv and carry on. Next fill up, just put the remainder of the petrol in the tank, too expensive to waste.
Pastyman..
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Hi
Not much difference to what was done in the past to stop diesel from freezing up. Toyota say you can run your diesel on petrol in the event that you run out of fuel and have no other fuel, short periods only of course.
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"Toyota say you can run your diesel on petrol in the event that you run out of fuel and have no other fuel"
I'd like to observe a cold start in this scenario!
All diesel cars accidentally filled with petrol often fail to start in my experience..
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Toyota say you can run your diesel on petrol in the event that you run out of fuel and have no other fuel, short periods only of course.
I don't doubt what you say but am surprised. My neighbour put petrol in his diesel Peugeot and the car came to a dead stop. It then wouldn't restart until we had purged most of the petrol from the system and replaced with diesel fuel.
Incidentally, my Rover 75 CDT handbook advises that putting petrol in a diesel tank, or vice versa, is harmful to the catalyst. I don't know if this is being over-cautious, and I haven't even looked to see if mine has a catalyst, but it's something worth thinking about if you put petrol in a modern diesel car.
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Incidentally, when petrol was put in a diesel tank to prevent plugging (waxing) in cold weather, this was typically only a gallon or so in a lorry tank of diesel.
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It's not the catalyst I'd worry about Dizzy, it's the high pressure common-rail fuel pump I'd loose sleep over!
Petrol has no lubricating properties, unlike Diesel fuel.
But, I agree, catalyst damage is possible after a spell of incorrect fuel operation.
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Good point, DL. Though Lucas relied on the very small lubricating effect of petrol for the petrol injection system used on the old Triumphs and Jaguars, the reduction in sulphur has probably taken most of the lubrication away.
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LOL! yes but look at the (un)reliability of the old Lucas PI systems!!!
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I know you\'re not being entirely serious but I must mention that the unreliability wasn\'t down to the petrol\'s lubricity (or lack of). For instance, I\'m not aware of any seizures within the metering unit despite the very close tolerances and the high linear speed of the shuttle reciprocating in its bore.
The Lucas system was unreliable because the pump was based on a wiper motor and could overheat, the pressure relief valve wasn\'t up to scratch, the camplate would wear, the injectors would stick and the maker\'s agents didn\'t have a clue as to how to diagnose faults and set up the system. Apart from that, it was fine!
Nowadays a lot more is known about how to keep it in good order and there are specialist parts available which are much more reliable than the originals. Having said that, I changed my present Triumph from PI to carbs in about 1976 and have never regretted it!
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Dizzy
Many years back a colleague, rather strapped for cash, reprofiled the worn injection system cam by hand on his 2.5 PI. Must have done a good job, because it ran very wellfor another couple of years 'till he sold it!
Regards
john S
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My Dad's colleague bought a new Audi A4 tdi, it stopped after about 20 miles after he picked it up from the dealer, the engine as seized/wrecke, the dealer had filled the tank with fuel, unfortunately, it was petrol.
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John S,
I managed to improve the poor running of my 2.5PI by repositioning the camplate slightly but didn't dare try reprofiling it. It still ran over-rich at most speeds but the consumption improved very slightly from the 15.9 that I'd been getting to just over 16! Yes, that's mpg!
The final straw came when, after overtaking a long line of cars on a busy road and then having to stop at a railway crossing, the car stalled, flooded and refused to restart - and the people in the cars that I'd just overtaken waved and laughed as they passed by!
I decided then that I either had to renew most of the parts in the system or change to carburettors. The cost of a twin carburettor setup using new parts was about the same as renewing the PI system (I think it was £170 in 1976 - very expensive) and I decided on carbs. That never worked very well, mainly because I couldn't get the needle profiles right and also because I was using 1.75 Strombergs on a very restrictive Triumph manifold designed for 1.5 SUs. Some years later I changed again to a standard Triumph 2500S carburettor system and that's been brilliant with excellent performance and around 30 mpg overall.
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I had an original 2.5PI Mark 2 1973. Never had any fuel injection issues at all in 3 years and 40k miles. Sold it with 120k miles on the clock - OK..
Maybe Lucas had sorted it by then or I was lucky. It had only 125bhp (or so) so not highly tuned.
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Always better to use diesel petrol in a diesel car. If u fill by mistake with unleaded car will run slowly.
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Your tongue was firmly in cheek, I trust.
I've never got it wrong yet....but there's always got to be a first time. No damage done in cases of misfuelling provided you realise your mistke before starting the engine.
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No damage done in cases of misfuelling provided you realise your mistke before starting the engine.
Some modern diesels start pumping fuel as soon as you unlock them, or open the door I understand. In which case you may need to drain and flush more than just the tank.
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Some modern diesels start pumping fuel as soon as you unlock them, or open the door I understand. In which case you may need to drain and flush more than just the tank.
I'm not aware of any that start pumping BEFORE the ignition key is put in and switched on - it would make maintaining the engine very difficult if fuel was circulating all the time.
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Modern diesels cannot start pumping before the engine is switched on as there is no return feed for unused fuel. So start pumping, Common rail up to pressure, no need to pump further.
Glowplugs switch on when you open the door. Then nothing until you switch on "ignition" ..
At least listening to my pump..
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Then nothing until you switch on "ignition"
Quite.
Do Heynes still include wiring diagrams? I don't understand how some of these rumours start!
Edited by unthrottled on 10/12/2011 at 22:27
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