Mercedes CLK 03 - Fuel contamination

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Wed 18 Jun 2014 17:18
Mercedes CLK 03 - Fuel contamination - Jacamole
Returning from a trip to France, we filled up with fuel at the BP garage in Reims. Just as we left the ferry in Dover masses of whitish/grey smoke bellowed out. We limped home at 40mph unable to accelerate as this seemed to cause the smoke to belch out. Our mechanic ran various checks ruling out a blown head gasket. When he checked the fuel he found that it was oily and concluded that the fuel was contaminated. The oil hadn't come from the car (oil was fine) and the last place we had filled up was in a France. The fuel was drained (we have retained the fuel) and new petrol put in. The car was fine until we returned from a 2 hour trip (rarely use car other than for short journeys at weekends) when the same type of smoke came bellowing out again. We decided to go to Mercedes this time. They've recommended changing the fuel filter and if that doesn't work they can run a full diagnostics test for £150. If there's something wrong we could be looking at four figures. We've written to BP in France but chances of being successful are slim.

Has anyone else had a similar experience and if so what was the outcome?
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Wed 18 Jun 2014 17:32
Mercedes CLK 03 - Fuel contamination - Armitage Shanks {p}

How did the car go about 150 milees to the French port you used, from Reims without blowing out any smoke? Then a 2 hour trip and another bout of smoke, doesn't soundtotally fuel related to me but I am not an expert in any way!

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Wed 18 Jun 2014 19:01
Mercedes CLK 03 - Fuel contamination - Jacamole
That's a good question and one which we asked early on. The thing is, the car already had a quarter tank of good fuel in it and the mechanics view is that it would take time for the bad fuel to work its way through plus with the car sitting on the ferry for an hour and a half would allow the oil to rise. As for the 2 hour journey, that could be for one of two reasons. 1. The car hasn't really been used since the fuel was drained so there could still crud in the fuel filter. 2. Or worse, the contaminated fuel has now damaged a part of the car like the pistons. We do have the fuel that was drained from the car and it isn't good. But we're not experts either!
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Wed 18 Jun 2014 20:22
Mercedes CLK 03 - Fuel contamination - leaseman

In my humble opinion, contaminated fuel from France is a total Red Herring.

There has to be a more logical explanation for your problem- the fuel issue is just unbelievable, under the circumstances you describe.

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Thu 19 Jun 2014 00:07
Mercedes CLK 03 - Fuel contamination - Cyd
The thing is, the car already had a quarter tank of good fuel in it and the mechanics view is that it would take time for the bad fuel to work its way through plus with the car sitting on the ferry for an hour and a half would allow the oil to rise.

Utter rubbish

Let me ask you something:
if you have half a washing bowl of hot water and add cold water, does the cold water sink to the bottom of the bowl and then take half an hour to mix with the hot to make warm???
No, of course not.

Add new petrol to a tank and it will mix with the old almost straight away.
Obviously it will take a mile or so for the new fuel to work its way through the fuel delivery system.

As fo roil sitting at the bottom of the tank and taking an hour to rise - also rubbish. Engine [and similar] oils will mix into petrol almost straight away - the petrol is a solvent. A petrol soaked rag is extremely effective for cleaning up an oil spill.

A similar myth exists about putting petrol into diesel - the petrol and diesel are perfectly miscible liquids and will mix easy and quickly. Try it in a jar and see for yourself.

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Thu 19 Jun 2014 10:20
Mercedes CLK 03 - Fuel contamination - Jacamole
So, how do we explain the oily fuel? The mechanic said petrol evaporates on contact. The fuel from our tank didn't. We took the car to mercedes yesterday and they have recommended replacing the fuel filter before conducting further tests. They didn't discount fuel contamination but as mentioned by another person it may well be a red herring which is why we posted here looking for help
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Thu 19 Jun 2014 11:55
Mercedes CLK 03 - Fuel contamination - Armitage Shanks {p}

The two fuels, the tank contents and what is added, will be well mixed just by the action of the fuel pouring into the tank, assuming they can mix ie are miscible. If you put petrol in a diesel it will die with a mile or two

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Thu 19 Jun 2014 12:17
Mercedes CLK 03 - Fuel contamination - Jacamole
Thank you, please see my reply to jc2

Edited by Jacamole on 19/06/2014 at 12:18

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Thu 19 Jun 2014 11:56
Mercedes CLK 03 - Fuel contamination - jc2

Most if not all modern vehicles-both petrol and diesel-use recirculatory fuel systems.The fuel is taken from the bottom of the tank,sent to the engine and the unused fuel returned to the tank-so it is continually being mixed while the engine is running.

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Thu 19 Jun 2014 12:16
Mercedes CLK 03 - Fuel contamination - Jacamole
Thanks. Do you have any idea how the fuel which was drained from the fuel tank might have ended up oily? The mechanic checked the oil levels after France and said it was fine. On the way home at the weekend though the car said it needed a litre of fuel. Normal considering the two big trips the car had recently done or indicative of something else? (I'm not mechanically minded at all so please bear with any inexperienced comments:-) )
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Thu 19 Jun 2014 12:42
Mercedes CLK 03 - Fuel contamination - dieselnut

You had the contaminated fuel drained & refilled with new fuel. There would have still been a couple of litres circulating the fuel system that would have re-contaminated the new fuel but only slightly.

I would think that the oil must be comming from your engine & getting into the fuel somehow. Is there an engine mounted fuel pump.

I would forget the Mercedes dealer unless you have deep pockets.

Find a good Mercedes independant who is familiar with your type of engine.

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Thu 19 Jun 2014 13:19
Mercedes CLK 03 - Fuel contamination - Jacamole
I will check about the engine mounted fuel pump. We have an independent mechanic (though as far as I'm aware he's not a mercedes independent) and only went to the mercedes dealer for a bit of guidance. They suggested changing the fuel filter first then for £150 they will run a complete diagnostics test. Once we know what the problem is we can then get our mechanic to sort it hopefully for a lot less.
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