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(97-00) 1.9 TDI - petrol in the diesel tank - shirike
Hello,

My Dad, who has been driving for 20+yrs, has put about 20 litres of unleaded petrol into the tank - he says it was about 3/4 full when he went to fill it up and he topped it to full (or close) with petrol.

D'oh.

He only realised after he drove 7 miles home - he says the engine ran fine and the first thing he knew was when he was checking the receipt.

I've looked around and I'm fairly sure he has avoided major damage due to the fact the car has probably only used diesel so far (with diesel being heavier than petrol) but I've told him he cannot try repeatedly topping it up when it gets to 3/4 because this could risk major damage to the engine.

We can't syphon the tank because it has a device fitted to prevent this - does anyone know:

1. If there's a way around such devices
2. If not, what it would cost for the tank to be taken out and emptied?
3. If the trick about topping it up with diesel until the petrol is diluted to a non-damaging level works?

{picked up estimated year from your choice in the drop down menu as you failed to mention it, despite the 3 separate requests asking you to include it!}

Edited by Dynamic Dave on 01/03/2008 at 18:02

1.9 TDI - petrol in the diesel tank - spikeyhead {p}
The petrol and diesel will be thoroughly mixed, they're miscible, unlike oil and water.

Just because the receipt says petrol doesn't mean that it was petrol that was added. Its not unusual for the garage to be wrong. Open the cap and do a sniff test.

There's no right option about what to do, it'll depend in part on how old the engine is. Is it a PD or an old style (pre 97) engine?

The cost of draining the tank when I filled my old Cavalier with petrol was £180, but that included recovery. Don't try siphoning the tank unless you have a good use for 15 gallons of mixed fuel. If it's a modern car then I'd get the tank emptied professionally, otherwise if its older or a high mileage PD engined car that's no longer worth much then I'd add some two stroke oil to aid lubricity and keep topping it up with diesel and accept that there's a small risk of it going horribly wrong.
(97-00) 1.9 TDI - petrol in the diesel tank - done - shirike
Sorry, Dynamic Dave, I promise never to do that again :)

I've discovered we can nip the end of a garden hose to squeeze passed the anti-syphon device (basically, it's a little bar with bisects the fuel pipe) - we'll be syphoning it tomorrow once we've found some containers.
(97-00) 1.9 TDI - petrol in the diesel tank - done - Dynamic Dave
Well tell me what the year is then, so I can edit in the correct one.
(97-00) 1.9 TDI - petrol in the diesel tank - done - Hamsafar
Sounds fairly old tech, I'd drain out about 5 litres and replace it with rapeseed oil from the supermarket to add viscosity and lubricity. Avoid higher RPMS (>3700rpm) and top up with diesel again at half full.
(97-00) 1.9 TDI - petrol in the diesel tank - done - nortones2
Depends on whether the engine is PD or not whether you can get away with adding vegetable oil, but I'd not be inclined to mess around any more in the circumstances. Just put in premium diesel after syphoning.
 

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