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Diesel in a Petrol Engine

Hi there, Over the weekend we managed to put 25 litres of diesel into a petrol engine of a new Lancruiser (LC4). It was driven around the block for a bout 1km before the car stalled and was pushed back to base. Please can you advise of the potential damage / solution? Thanks. Dan

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Hi If the vehicle only traveled a short distance and not at high speed, I cannot see it doing any damage to the engine ( a compression test would show if there is any damage ) What i would do is clean out the fuel system and change the fuel filter also change the engine oil and filter just in case of contamination Peter

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I think the engine should be ok, putting diesel into a petrol engine has less potential for mecchanical damage than petrol into a diesel one. There may be a build up of carbon around the valves and the petrol fuel injectors will need to be replaced, as might the petrol injection pump. there should be no mechanical damage to the head, valve gear or pistons. The most likely reason for stalling is that the spark plugs got fouled. or the fuel injectors got blocked/damaged. The First thing I would do is drop the fuel tank out and empty the diesel out. You then need to disconnect the the fuel lines between the tank and let them drain for a few hours. Throw away the fuel filter, your vehicle needs an early service. Check the service manual on the vehicle to see if there is an inline fuel between the tank and the main filter (sorry it has been many years since I worked as a mechanic and a log and I am not up to date on the engine. If you don't have a service manual then you can get Hanes manuals for most Toyota's in the text book centre in Nairobi.

Second thing is to check the plugs. this can be done visually, if they are very oily clean them with a cloth soaked in petrol and then rub them with some emery paper. You can check the plugs are sparking by leaving them attached to the leads and earthing them by holding the bottom of the plug close to the head and turning the engine over. Be careful doing this, holding the spark plug away from the hole where the plug is screwed into the head, otherwise you risk singing your eyebrows. Safest thing to use a spare plug to block the hole of. Use a pliars to hold the lead and make sure that it has insulating rubber on the handle. Do this before cleaning them. If you don't get a spark ten you have isolated one possible cause of the stall. Once you have the fuel system drained, try replacing the plugs, fill the car with petrol and see if it runs. If it does then check the fuel pump for signs of leaks etc. I am not sure what kinds of filter elements there are in the injection pump, but they may have to cleaned. I could go into ways of manually exhausting diesel from the pump body, but I would be writing a manual in an email. Your best bet in this case is to call the toyota rep in Juba and see if they can get a mechanic to your location by air. Damage to the fuel pump or injectors will require a specialist mechanic and equipment to diagnose, and I am not about to try and do this by email from another continent.

If the car does start then I would store your petrol and diesel in separate ... (more)

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2014-01-27 10:13:19 -0500
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Last updated:
Jan 27 '14