Petrol in 3.0 TDI, now won't start.

[c.grex]

My mum has told me today that she put around 10 litre of petrol in her A4 and then topped it up with around 45 litre of diesel! She has run round this week and done around 50 miles and she she had a issue with it not starting the other day, but then it did. Now she has done a 5 mile trip out and called to say it won't start!

I have VCDS and have done a scan and its all clear, just I case it was anything else.

i know she shouldn't have topped it up and got it drained, but she didn't and I'm just wondering what to do next? She's in the AA. Any advice gratefully received.

[NHN]

You need to completely drain the system, I'd say possibly all the way up to the injector point, remove filter, clean out the housing of any fuel & fit new filter & hope it hasn't damaged any internals of the fuel system, as a afaik the diesel is also lubricating the parts, whereas petrol doesn't lubricate anything, so may have caused damage.

Take your chance on doing this & try starting the car, but cant say if its done the damage already.

[Brycie]

Hi Chris, what a nightmare, but easily done. I'll let Zollaf expand on this, but I've seen in previous posts that he says up to 25% petrol in a diesel tank is ok as long as it's brimmed & kept brimmed for a while in order to dilute it as much as possible. NHN is quite right, diesel does have a lubricating effect on the engine where petrol doesn't (it has a cleaning effect), so the ratio of petrol to diesel may have done some damage & it's best to get a full flush/filter change to be on the safe side.

Good luck with it though mate, keep us posted.

[c.grex]

Cheers for the replies guys. If she had told me when it had been done I would have had it drained ASAP and then refilled.

I'm going to get in touch shortly and think we'll tow it somewhere locally to get it drained and take it from there.

[gupsterg]

I came to this thread via being nosey :o ... I hope your mums A4 is AOK c.grex :) ...


I'll let Zollaf expand on this, but I've seen in previous posts that he says up to 25% petrol in a diesel tank is ok as long as it's brimmed & kept brimmed for a while in order to dilute it as much as possible

Zol states this in the context of PD TDi's ... CR (common rail) which the 3.0 TDi is, I believe has way lower tolerance to petrol ...

[zollaf]

yep, pd's are ok up to 25 %.
so how did the po get on then ?
c.grex, are you there ???

[c.grex]

Sorry for not updating!

Not sure I'd do it again, but we left it parked for the day and then went the day after and it started fine. Gave it a 150 mile run out and then topped tank up. It's had a ride round Scotland a couple of weeks ago (over 1k) and its running like a dream!

Lucky!

[zollaf]

oooh, thats good to hear then, wonder why it stopped though, petrol doesn't normally stop one in small quantities like that unless it has blown the high pressure pump.

[gupsterg]

I think you mum's probably got so scared by the whole thing that she won't be doing that again in a rush!

All's well that ends well! :approve: ...

[Guest 2]

Thankfully your B8 should have a special filler neck which won't let you put a petrol nozzle in it!

Obviously her B7 didn't :rolleyes: