emergency please help

[MargeB]

Does anyone know how to open the fuel supply line on a Rover 75 estate in situ (no ramp) to drain the tank (my mate has put petrol in a diesel engine). Tank had some diesel in it, only 5L of petrol went in. Guess not safe to run?

Thanks.

[chwinc]

fill it up with diesel and it will be ok, will dilute it enough not to harm the pump etc.

[Andy Boz]

I'll second that.

[KebabMeister]

Chwinc, it's not the pump you have to worry about, it's the combustion chamber.  Diesels have a much higher (sometimes twice as much) compression ratio (petrols are 9 - 10:1 whereas diesel 15 - 20:1) so that means that a more refined fuel, petrol, will explode before it is supposed to (it's designed for diesel fuel).  This is called 'pinking' or pre-detonation of the fuel.  In extreme circumstances it can melt the cyclinder head, valves and pistons.  I can't honestly say whether diluting would be entirely safe and personally I'd say it isn't worth the risk.

AFAIK there is no drain plug on the 75 fuel tank and so you have two options.  Either syphon the tank or remove the tank.  Some garages would even flush the entire system but we never used to do that and we never had any problems.

(I used to work on Rovers)

[chwinc]

I lecture in automotive engineering and being a mechanic with 20 yrs experience 5l of fuel in a full tank will not cause the extreme damage you mention, we in fact used to put petrol in diesel fuel tanks in trucks to prevent cfpp or waxing of the fuel

[KebabMeister]

Well if you're offering a guarantee then MargeB is very lucky! :)

We were always lectured not to have any petrol in a diesel car engine for the reasons I stated.  Obviously truck engines are a bit heavy duty than a Rover diesel engine based on a petrol engine (notorious for engine problems) but I personally wouldn't take the risk especially after seeing two cars that did run on petrol once.

[Potato]

Is this article any good?

[marje]

My husband put petrol in my Peugeot 206 diesel and was told it would be okay. NOT. He took out for a run and parked, when he tried to start the engine again, it wouldn't go.  Had to have it recovered to a garage, which luckily was covered by Greenflag, but had to pay for the tank draining, it had about 30 pounds worth of fuel in, and clearing out. Total cost including diesel to get him home - over 116 pounds.  Apparently the newer engines won't tolerate having petrol put in them.

[Andy Boz]

Change your mate!

I would have no quialms about a drop of petrol in a diesel engine. If it is any easier, find where the fuel pipe runs into the engine bay, disconnect it, and either syphon or use an electric pump at this point. HOWEVER, if you do this, remove the fuel cap from the filler before commencing operation. Then you may have to bleed the system....