Lotus Elan and Lotus Elan Plus 2 Forums

Yes, I did the unthinkable. Filling the tank with supadupa BP or Optimax, V power or whatever as I like to do, I picked the wrong nozzle. 20 litres in I realised so I filled the rest with petrol to dilute it. I only drove the mile or so home and I have to say the car went better than ever, BUT..........am I right in thinking that apart from a sooty exhaust no harm will be done.
Jim the foolish one (friend of Pete !!)

Drain the tank, including the line to the engine, put in a gallon or two of GASOLINE, drive the pants off it for a few miles, drain it. Then refill with GASOLINE ONLY FROM NOW ON and you should be fine.

Jim (new boy)

Will probably give the top end some much needed lubrication...no problem...

John

So....................will it be ok? does anyone know?
Jim

It will be ok if you didn't drive too far and it doesn't sound like you did. The carbs (what type do you have?) certainly aren't designed for diesel, I'd drain the system ASAP if it were my car.

Ohh dear

Diesel is oil so all the surfaces will be coated in oil. This is not so bad with carbs as it would be with the fine tolerances of modern injectors.

I would drain the system and expect to have to clean out the carbs a few times as the oil cleans off of the tank walls and fuel pipes. I would expect the spark plugs to soot up and the carb jets to block up not a major problem.

What is worse is if you put petrol in a diesel car as the diesel lubricates the pump.

Jason

The greatest danger is preignition. Diesel fuels have lower self-ignition temperatures than do fuels for spark ignition engines. Therefore there is real potential for damage to your engine. I would drain the tank immediately. I would not get too fussy about cleaning everything out though. Gasoline (petrol) will clean the system out pretty well on its own. Gaoline and diesel fuels are both mixtures of low and high molecular weight hydrocarbons and both have oily residues.

Well, thankyou for all your advice, even if asking the audience brings conflicting views, the general consensus was to drain the tank. My mechanical knowledge, gleaned from the Ladybird Book of Car Engines (reading age stiil made me think that diesel needs a much higher compression to pre-ignite and the fact that I`ve seen mechanics cleaning components with diesel suggested Armaggedon wasn`t imminent. So, I simply syphoned off most of the tanks contents, sloshed in a 2 gallon can of petrol and drove to the petrol station. With a cold engine there was a bit of coughing and a very smokey exhaust, but once filled with supadupa BP, the engine cleared and ran perfectly. Down to Donnington and back the car hasn`t missed a beat.
Thanks again,
Jim

jimj wrote:My mechanical knowledge, gleaned from the Ladybird Book of Car Engines (reading age stiil made me think that diesel needs a much higher compression to pre-ignite and the fact that I`ve seen mechanics cleaning components with diesel suggested Armaggedon wasn`t imminent.
Jim

Keep in mind that fuel is injected into a diesel's combustion chamber at the time that ignition is desired. This is very much unlike a carburetted spark ignition engine in which fuel is present in the combustion chamber throughout the compression stroke. The high compression ratio of a diesel is needed to start the engine from cold even with glow plugs. Once warm a diesel would actually operate with much lower compression ratio. It seems as though all has worked well for you in the end, enjoy Donington, we have a few Yanks over to visit.

"The Devils in the daezel" as a poet friend observed, but not in the context of an Elan. Yes, I've just copied jimj with 15 litres and realised my mistake after half a mile. It took a while after a similar amount of 97 to restore power enough to drive on the road but it's a bit hairy, pre-igniting on throttle (for which I've retarted the ignition) and I'll have it drained on Saturday. It overheated violently with oil temperature up to 80?C and water over 110?C after short drives.

Hope to take it to the Revival Saturday to view the car park and on Sunday for the racing. Haven't seen jimj's car there since 2007.

Not just me then.. I put 10 litres if diesel into my car earlier this year... and wondered why it was smoking.

Garage drained the tank for me, put some fresh fuel in, added some engine cleaner , adjusted the timing and the car has never run so well since...

Carl

Putting diesel into petrol is not too drastic, cleaning it out and fresh fuel should fix it.

The other way around however (putting petrol in diesel cars can be disastrous), the petrol is not an adequate lubricant for the fuel pump and the friction can destroy the expensive high-pressure fuel pump.

Unfortunately the preignition blew the head gasket at its weak point causing the sump to fill with diluted antifreeze. Time to get the rear of the head fixed properly now I'm back from holiday.