Diesel car running rough after putting Petrol in

MiserlyMartin

I accidentally put only 2 litres of petrol in before realising what I was doing. I stopped and filled up to the fuel tank neck with Diesel. If this is relevant the tank was about 1/4 full at the time of the petrol. I figured that 2 litres wasn't much of a bad mix for a 60 litre tank, being only about 3% of this mix was petrol, so I ran it and hoped for the best.
It intially started with no probs and ran fine on a 100 mile motorway run.
Its been absolutely fine for 2 months. I must have filled up 3 times since then no problems. But I noticed a few weeks ago that when I accelerate in the lower gears between 1500 - 2500 rpm its getting a bit jerky mainly while accelerating slowly. If I put my foot down (and the turbo kicks in) I don't notice it. Its a 306 2.0 Hdi.

1. Have I done any long term damage?
2. Should I get the fuel filter replaced?
3. Should I get anything else replaced?
4. Should I get the tank drained or would I have burnt the petrol off by now?
5. Have I got away with it and this rough running just means it needs a service? (although petrol prob didn't help!) It was last serviced 8 months ago, but if the garage actually did replace any parts who knows! This garage is not very trustworthy but I had no choice to take it there because that was where the breakdown truck towed it. After fixing the problem they also 'serviced' it.

Any advice would be great

MarkyMarkD

I think that, because diesel's denser than petrol, the diesel will have sunk to the bottom of the tank leaving petrol at the top. You would only use up the petrol if you ran the tank quite empty each time.

It would probably have been wiser to get the tank drained at the outset rather than mixing petrol and diesel.

Older diesels are a lot more tolerant of petrol than newer ones like yours.

I think you should take your car to the garage and tell them what you've done, and take their advice as to what might need replacing.

tomstickland

It might be totally unrelated. I certainly wouldn't think that that little petrol would be a problem.

nickmack

MiserlyMartin wrote: »

1. Have I done any long term damage?

Hopefully not in this case, 2 litres Unleaded in 60 litres of Diesel, you should just get away with.

2. Should I get the fuel filter replaced?

Would be a good idea if it continues to run rough.

3. Should I get anything else replaced?

Get the fuel pump, fuel rail seals and injectors checked

4. Should I get the tank drained or would I have burnt the petrol off by now?

Probably not worth it now, just keep filling with diesel to reduce the ratio of unleaded.

5. Have I got away with it and this rough running just means it needs a service?

Possibly this time. A very small ratio shouldn't do any major damage. Older diesels tend to cope a little better. Newer models using high-pressure direct injection may be less tolerant.

Generally it's recommended you don't start the engine at all and have it drained if you put the wrong fuel in to be safe.

x_raphael_xx

I had half a tank full of diesel (I don't like to go less than this) and filled it right up to the top with petrol so it was half/half.

I just drove the car until it dropped to half again and re-filled with diesel. I didn't replace or clean any filters or anything, and while it was very sluggish (up hiill etc) until it was full of diesel again there was no damage done and MOT passed after.

Petrol into a diesel car you can usually get away with. Diesel in a petrol car is a no-no.

MiserlyMartin

I'm surprised about that, was that an older diesel car? Thanks for the replies so far.

Nickmac said "Get the fuel pump, fuel rail seals and injectors checked". This sounds expensive. And how do they go about checking this? My knowledge of diesel cars engines is not good, I understand petrol a little better!!

tomstickland

I think the petrol corrodes the rubber seals in certain items. A visual inspection by a garage would be OK.

I reckon you should call round a decent garage and have a chat with them about what might have happened.

cardtart_2

hi i filled my 1997 1.7 diesel with half a tank of petrol then realised so filled it up with diesel .you may not believe this but it actually ran better.I have heard since that some people put a couple of litres of petrol in a full tank of diesel in winter to make it run better.but i wouldnt try it.

x_raphael_xx

MiserlyMartin wrote: »

I'm surprised about that, was that an older diesel car? Thanks for the replies so far.

Nickmac said "Get the fuel pump, fuel rail seals and injectors checked". This sounds expensive. And how do they go about checking this? My knowledge of diesel cars engines is not good, I understand petrol a little better!!

Mines a 1993 Corsa, the day after I did it I drove up to see my mum, the journey there and back uses half a tank, and I re-filled with diesel as soon as I got back. So maybe because it wasn't in the car for long nothing was affected too much??

david29dpo

Putting petrol in a diesel can ruin the pump. The pump is lubricated by the diesel going through it. Petrol on the other hand is a very good cleaner, and a pump with petrol in it have been known to size overnight or be damaged beyond repair.

Conor_3

When it's very cold, sometimes petrol is mixed with diesel to stop it freezing...