help - petrol in diesel

[maldon]

Never had a diesel before. First time at pump managed to get £ 2.60 worth of petrol in tank of ML270CDI - I have filled up to the brim with diesel (about 53 quid) the car had about a quarter of a tank of diesel.

Have all the diesel pumped out or what?

 

[anyweb]

nah just drive until about a quarter of the tank is used up, then refill it to full again, keep doing that for a couple of weeks and all will be fine

cheers

anyweb

 

[malcolm E53 AMG]

Awful feeling, brings you out in a cold sweat. With the old diesel engines before the high pressure CDi it was common practice in winter to thin the diesel down with a small percentage of parafin, not sure whether anybody used petrol.

More modern fuels with additives did away with the practice. I run a E320CDi and personally I wouldn't risk it even with the mix containing just 5% petrol that you have in your tank. The high pressure pump relies heavily on the diesel fuel for lubrication and can quite easily be damaged. I'd drain the lot!

 

[tom7035]

Just a drop in a bucket, won't do any harm. Don't worry about it.

 

[maldon]

I recon with the diesel remaining in the tank, just over a quarter of a tank it is down to 3.5%

Would it be OK to drive 50 miles to work and then have the tank pumped?

 

[malcolm E53 AMG]

Probably better to ring the Merc dealer you bought it off, mind you I'd be very surprised if he said drive it. There have been many threads on this site about your dilemma a search might help. I'd bite the bullet and get rid of it!

 

[george shand]

Do a search for "unleaded petrol for diesel engine" and you will find a post by ; lwlwoo ; which is almost identical to your problem and should give you plenty information on the pros and cons.

 

[mike65]

I would'nt worry, in olden days you could stick up to 20% petrol in derv and it would not kill the engine/pump. Even though they are more picky these days that % won't do any harm.

Mike.

 

[tom7035]

Do a search for "unleaded petrol for diesel engine" and you will find a post by ; lwlwoo ; which is almost identical to your problem and should give you plenty information on the pros and cons.

In other words maldon, RELAX and forget it!

 

[panason1c]

I would'nt worry, in olden days you could stick up to 20% petrol in derv and it would not kill the engine/pump. Even though they are more picky these days that % won't do any harm.

Mike.

I agree, that's a very low % and will not cause any problems imo.

 

[maldon]

Thanks to all for the input.

Am aiming to siphon off a good amount and top up so as to dilute as much/quickly as possible.

 

[jberks]

I'd just say I agree with most of the posts above. It is less than 3.5% of the tank. The diesels are built to handle dodgy diesel in easter european countries and poor maintenance with taxi mileages - hence why they can be chipped in the UK. So given the fact that the system is run on good diesel normally and properly maintained, a fractionally weaker mix once will do no real harm. As above, I'd use 1/4 tank then fill up and repeat 3-4 times and not worry about it. You'll probably find that the tank is anti syphon so getting the fuel out is going to be a major task and probably not worth the effort.

 

[SLinKyjoe]

the amount you have put in which you have then diluted will do no harm. altho, in theory*, it should help the staring of the car in very cold conditions as it reduces the ignition temp that diesel combusts at! so it should help it start better in the cold weather for a few days or so until you dilute it further. stick with the above, fill up at 3/4full, or use 1/4 tank and fill up. makes your feul stops seem cheaper when you only put £15-£20 in every time.

dont bother with syphon. diesel and gosoline are bed chums. they mix well. if you leave it the nautral heavier crude deisel does settle and the petrol will appear to sit on it, but it mixes so you are wasting your time. diesel will seperate the constituants of gasoline and if you leave it long enough it will break it down so you cant see it. but with the motion of the car it will mix it.



* theoretical as deisel is compressed which in turn generates the combustion temperature, so whether it will make a difference is up for testing, but it will reduce the ignition temp of deisel by about 20C( with a mixof about 5%).
it will also reduce its flash point to below 70C too but thats only useful if you intend to light it in a bucket.

 

[Bolide]

Rtfm

Read the owner's manual and see what it says

The manual for the W124 gives the maximum percentage of diesel you can put in a petrol car & vice versa. Completely different diesel engine & things are different with modern common rail engines but I'd RTFM


Nick Froome
www.w124.co.uk

 

[lwlwoo]

Hi Maldon,

For some reasons my earlier reply was not posted after I submitted it and so I'll do it again.

I had the same problem a few months ago, albeit the level of contamination by petrol was less than yours at 1.7%. If you do a search on the subject you can read the full story and all the replies.

Just keep diluting the contaminant by frequently topping up with more diesel. I did this until the level dropped to around 1%, then gave up and finished off the remaining diesel in the tank.

In theory, I would agree with any expert that a reduction in fuel lubrication may cause harmful effects to modern common rail diesel engines because of the high pressure involved. However, in practice and from my own research, the tolerance level of Cdi engines to contamination by petrol could well be higher than what we've got.

The jury is still out on whether my engine has been damaged by this incident of petrol contamination. What I can say now is that my 2000 E320 Cdi is still running as quietly and smoothly as before. So, if there is a problem I reckon it is insignificant or unnoticeable yet.

I hope this will reassure you.

 

[maldon]

lwlwoo - thanks for that - I have been in a state of panic, having just had a look round on the internet, with various conflicting stories. The actual amount of contamination was £ 2.20 worth of unleaded so I think I have 2.2l of petrol to 73l diesel.

Everything seems to be OK. Am going to top up the 65 miles worth of burnt off fuel this morning, and then will have about a hundred miles to cover on Friday - again topping up at the end of the trip.

I would LOVE to find out what the contamination tolerance is for these CD engines and whether or not there is any additive that can be used to maintain the lubricant value of straight diesel.

 

[lwlwoo]

Hi Maldon,

I was recommended Millers Diesel Plus additive which is available at most motor accessories shop at a reasonsible price. If it doesn't do magic for the engine at least it will work as a placebo and have us reassured pyschologically.

It is unlikely one can determine the tolerance of petrol by Cdi engine accurately apart from working out a lower limit where damages may happen. The variation can be large and so it would be difficult to gauge. To make things more complicated, different engines will have different level of tolerance for sure. No manufacturer will bother to do this research for the customers, MB included I reckon.

 

[maldon]

lwlwoo - thanks again.

 

[yidthekid]

Don't Worry

As an Ex lorry driver, it was comman practice to put a pit of petrol or parafin into the diesel tank in the cold part of the winter to stop the diesel getting so sticky. it won't do any harm at all, especially in the percentage you spoke of.

 

[kwh]

500 DSL (Die SL? Ja, Die SL!)

i lent my 500sl to a friend and he put £20 diesel in a near empty tank,
managed to get it about a mile, sputtering, back to my house so he could
wake me up at 5:30 am, my first day of redundancy after 10 years of
ridiculously long hours, days weeks and months of work. What a guy.

I was not happy, neither was the car, and its fuel pumps have been noisy
ever since. But it didn't die.