Help please ,petrol into diesel - Mercedes-Benz Forum

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post #1 of 8 (permalink) Old 05-21-2008, 08:38 AM Thread Starter
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Unhappy Help please ,petrol into diesel

My car => C200 CDI Classic AUTO SE

After driving diesels for years I finally
made the dire mistake of putting in unleaded.
The tank was pretty near empty & I put 11 litres
of unleaded in. I drove home (1/2 a mile) in
ignorance & about an hour later I went to go
out again. It started as usual but then the revs
dipped very briefly. The engine never does anything
but purr like a kitten at idle so it got my
attention - and suddenly I realised what I'd done.
Needless to say I switched it off & it's been like
that since.

I'd be very grateful for any advice. Please
bear in mind I am no mechanic.

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post #2 of 8 (permalink) Old 05-21-2008, 09:47 AM
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It needs to get a full flush. Not good that the petrol entered the high pressure pump, rails and injectors. Perhaps the pump and injectors are still OK since you did not drive too much. But flushing the tank, fuel pipes, filters and the CDI parts isn't straightforward if you are "no mechanic", better to leave it for an MB shop or a good independent.
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post #3 of 8 (permalink) Old 05-21-2008, 10:07 AM
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Quickly have it cleaned. 11 litres from the whole tank?
Was the tank completely full after filling?
I would not start the car again.
You will need new fuel filter.
and have the tank emptied completely.
Be very careful with flushing it can damage your injectors.
Get better quality diesel do not rev the engine to high rpms after start.
I don't know where is the fuel filter located but if it is close to or in the engine compartment put in diesel fuel in it.
if it is closer to the engine it will help mix it with the leftover of gasoline.
Remember you may loose your warranty for engine components if you go to MB.
Every good independent mechanic should be able to that.
But I see no choice as well just to get it towed .
1/2 mile is not bad for driving should not do any or very little damage but leaving the gasoline fuel in injectors could.

Good luck it will ended all well.

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post #4 of 8 (permalink) Old 05-21-2008, 10:25 AM
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My father in law did the same thing. Cost him a few hundred to get it all cleaned out. His was a big ford truck though. Dont know how much a mercedes indy will cost.

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post #5 of 8 (permalink) Old 05-21-2008, 11:33 AM
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This one is a CDI engine, there is quite a lot of fuel in the rail too. Not only flushing the fuel filter and fuel lines and the tank is sufficient. The high pressure pump is sensitive for lubrication, petrol isn't any good for it. Give it to someone who knows how to do it.
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post #6 of 8 (permalink) Old 12-17-2010, 06:38 AM
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hello all HELP

I have a new GLK 250 CDI ( 800 kms on it) . Added about 35 litres of gasoline by mistake on top of about 15 litres of diesel. Drove about 3 miles to my parking garage and left it there for about a week. Went to drive it today and it was a little difficult to start and then as I went around the block it stalled several times at low revs so I took it back inside the garage. I wil take it to Mercedes in January but I need to leave it for three weeks first as I will be away. Is this a problem? Need to know asap as I fly out tomorrow morning. Thanks

Last edited by Norval; 12-17-2010 at 06:40 AM. Reason: correcting typos
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post #7 of 8 (permalink) Old 12-17-2010, 09:04 AM
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35 l of gas on the top of 15 l of diesel? It is wonder the engine does run at all. I don't think parking the car for now will change anything.
I heard lot of the stories about adding some gas to the diesel and never have heard about that actually costing a damage. Usually it was below 30% of gas and common advise was to top of the tank ASAP and drive carefully. Sure having 70% of gas calls for proper drainage.
Good luck.
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post #8 of 8 (permalink) Old 12-19-2010, 05:32 AM
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my brother has done this on 5 different occasions. He also drove it till it ran funny then shut them down. It is not good on your engine but it probably wont kill it. Flush as much as you can out, Refill full of diesel and go. I would not let strait gas sit in the fuel system for long (bad on seals, could cause deposits).
I have spent alot of time on the farm with many diesels but am not a professional.

From what I understand the damage has been done, so there can be no harm in flush/refill and try.
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