Petrol in a diesel engine

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Ken - 28 Apr 2008 10:13 GMT

The other thread about someone using the wrong oil prompted the
following:

Does anyone know what exactly happens if you fill a diesel tank with
petrol? Someone once filled a petrol tractor from the diesel tank and
it was not happy (just drain and replace). But I am curious about how
petrol performs in a diesel engine. I doubt that the result would be
spectacular. Diesel has a higher energy density than petrol so petrol
is unlikely to blow the thing up. So I would expect that petrol would
work. As with oil, I suspect that the net result would be nuisance
rather than disaster.

But has anyone tried/experienced it?

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malc - 28 Apr 2008 21:28 GMT

> The other thread about someone using the wrong oil prompted the
> following:
[quoted text clipped - 9 lines]
>
> But has anyone tried/experienced it?

This has been done to death on uk.rec.cars.maintenance. The consensus is
that modern common rail cars can't go very far like that as it knackers the
injector pump (which relies on the lubrication of the diesel). An older
simple diesel like a 405 or earlier Xants should be relatively ok so long as
you don't go too far, they do get very rattly and bangy though or so I've
been told.

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Malc
Do not use the area outside this door for a urinal

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Doki - 28 Apr 2008 22:59 GMT

>> The other thread about someone using the wrong oil prompted the
>> following:
[quoted text clipped - 16 lines]
> long as you don't go too far, they do get very rattly and bangy though or
> so I've been told.

You used to be able to add quite a lot of petrol to your tank of diesel in
days of yore to prevent waxing during winter. Apparently 25% petrol was
allowed in old Golf diesels, and a bloke in PPC running a 205D on veg oil
adds a bit of petrol to a tankful to thin it down a tad. In something like a
ZX or similar that's nice and simple, you should be fine.

Common rail and you'll kill the pumps...

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Ken - 29 Apr 2008 06:33 GMT

> >> The other thread about someone using the wrong oil prompted the
> >> following:
[quoted text clipped - 24 lines]
>
> Common rail and you'll kill the pumps...

The consensus seems to be that if you put petrol in a diesel tank by
mistake, if the proportion of petrol is low when you discover the
error, probably filling up with diesel immediately will be sufficient.
If the proportion of petrol is high (>50%?) maybe drain the fuel tank
and replace. As I said, the reverse is not the case. Someone (everyone
denied having done it) put diesel in a petrol tractor here and it was
unhappy - it would stop often and restart with difficulty. Drain and
change was the only option.

Waxing of diesel was a problem in Australia about 20 years ago - the
refineries changed their settings (and denied having done so) and
whole fleets of tractors were unstartable in winter until you blasted
them with heat. The outcry/outrage of users was sufficient to prevent
it happening again (up to now anyway).

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Doki - 29 Apr 2008 07:55 GMT

>> >> The other thread about someone using the wrong oil prompted the
>> >> following:
[quoted text clipped - 38 lines]
> unhappy - it would stop often and restart with difficulty. Drain and
> change was the only option.

I really wouldn't chance any proportion of petrol in a common rail car. For
the sake of losing the cost of a tank of fuel VS the cost of swapping the
pumps, it'd be the tank of fuel that's swapped every time for me.

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G.T - 01 May 2008 09:52 GMT

Hi,

> I really wouldn't chance any proportion of petrol in a common rail car. For
> the sake of losing the cost of a tank of fuel VS the cost of swapping the
> pumps, it'd be the tank of fuel that's swapped every time for me.

Eeeer, pumps, injectors... Mostly all of the fuel line indeed, if the engine
doesn't burn in the meanwhile !
A friend of mine (OK, a friend of mine's wife) filled up her 406 HDI with
petrol. She saw it immediately and called the hauler, she just had to cope
with a tank flush, seems to run fine anyway.

I've heard of a guy which did the same with a Safrane 2.5TD (crappy engine
anyway) and didn't realize - I won't explain the details of the story - and
despite being an old-class Diesel, had to change fuel line and the complete
engine.

Regards,
--
G.T

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Keith W - 01 May 2008 16:43 GMT

> Hi,
>
[quoted text clipped - 15 lines]
> complete
> engine.

They must have been tougher in the 60's. A colleague tried to save me some
hassle and filled up the Morris LD diesel Royal Mail van that I was to drive
that afternoon. Unfortunately, the petrol and diesel pumps being side by
side, he filled it with petrol.

I arrived and went on my trip and for the first 5 or 6 miles it ran fine but
then started to kangaroo a bit. Fortunately my journey took me past the
workshops so I pulled in and, after examining it, they told me it wasn't a
f###ing two stroke.

They drained the tank, refilled with diesel, bled it and sent me on my way.
It ran fine for some years after that.

The pumps in the yard were hand operated and shortly after that, the same
colleague put the petrol hose in a van and proceeded to turn the handle on
the diesel pump. Unfortunately he was standing directly below the nozzle.
Ruined his suit and his car stunk for weeks because he'd driven home in it
to change.

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Keith Willcocks
(If you can't laugh at life, it ain't worth living)

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