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Unleaded Fuel

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by win230SL, May 6, 2009.

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  1. win230SL

    win230SL New Member

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    Hi there,
    Sometime ago, for the first time i put unleaded fuel in my 230SL 1970 automatic. Previously i had used 4 star fuel, After driving about 1/2 mile i noticed the car stuttering and losing power. i have never had any issues with performance before. I managed ti 'limp' to the lock up garage and there the car has been until now.
    I want to get it out this year but it will not start (no ignition). I beleive it's due to the unleraded fuel. Can anyone let me know what could be the cause and remedy for this problem, PLEASE!
     
  2. Myros

    Myros Senior Member

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    the unleadedness will not have had any effect

    in half a mile, believe me. what will have had an effect in that distance is any cr*p, cr*d, or water that might have been in the fuel tank already, or in the new fuel you put in.
    Was it your usual brand and octane rating and filling station, and was it a Big brand fuel. had they just had the tanker in and consequently sold you a tankful of fuel and bits of dirt.Does your SL usually fire up no trouble after an off-season sleep?
    To be safe, you'd better drain the tank, change the fuel filter, get the plugs out and see if they are fouled, and try again with good, new , clean fuel.
    You'll be ok with one in four fillups of leaded over unleaded. Your SL shouldn't give you any grief over it.
    Let us know how you get on.
     
  3. Alex M Grieve

    Alex M Grieve Senior Member

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    Cross overs - diesel from a petrol pump.

    People put petrol into diesel cars and some put diesel into petrol cars.

    What we tend not to hear about, but which does happen, is that the fuel delivery driver put the wrong fuel in the wrong pump at the filling station. (known in the trade as a "crossover").

    It sounds as though you could have received diesel, regardless of what the pump said. Worth trying to recover the receipt for the fuel if you can, and to get a sample of fuel from the tank. If it is diesel, and your receipt says petrol, then the filling station will almost certainly have had other cases and it is clearly their duty to fix it for you, or to reimburse you if you have to arrange it yourself.

    Good luck - tell us how you get on.
     
  4. television

    television Always remembered RIP

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    It would take several thousand miles to do any damage to the valve seats, something else wrong here
     
  5. Alex M Grieve

    Alex M Grieve Senior Member

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    Agreed Malcolm, and until such time you would not notice any difference. My money is on "miss fueling" here.
     
  6. roofless

    roofless Senior Member

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    i think you needed to adjust the timing for unleaded on older cars & if fitted to this model the octain adjuster plug might need set though long term it would need the valve seats done
     
  7. rapide

    rapide Senior Member

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    wrong fuel

    these are 4 star models but will have enough lead memory in the valve seats to run for thousands of miles as long as you are not pushing it hard ie; flat out all the time! as the guys have said its rubbish fuel you put in! a good clean out as said, fill it right up with anything ( petrol that is) and blow the cobwebs out of it, just drive it as normal, if in time the performance drops with the compressions you will have to have the valve seats done! but until then dont worry! all the best.
     
  8. OP
    win230SL

    win230SL New Member

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    Thanks Rapid and Roofless, i was also thinking on the same level as you guys. i had previously only used 4 star fuel. i am in London England and 4 star is not available, so my only option was to use unleaded fuel. Now the car wont start. i need to get it started to get it to a good garage. Someone suggested Redex. Any thoughtys on this?
     
  9. Myros

    Myros Senior Member

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    if your plugs are fouled

    as it sounds as though they are, then redex wont help. The easiest thing to do is take one plug out first, see what state it's in. If it's light-grey or light brown and the electrode gap looks to be about 0.7mm, then the problem is elsewhere, probably a clogged fuel supply.
    If it's black, or oily, then the problem is that your plugs are fouled, probably by the iffy fuel you had, or something else. Clean them up and try again to start it. If they foul up again, and they will quickly if you have dodgy fuel, then you know your problem.
     
  10. nickcc101

    nickcc101 Senior Member

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    When you say no ignition do you mean that the warning lights are on, the engine turns over but fails to start or that you have no warning lights or power ?
     
  11. turbopete

    turbopete Senior Member

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    id go along with the fact that if the fuel isnt messed up, it wont be the fuel that caused it. also regarding the lack of lead in the fuel, if the car has manual adjustable valve clearances as opposed to hydraulic tappets, loosen the setting for the exhaust valve by 0.3mm (4 thou) to reduce valve seat burn. this was used successfully by ford in their ohv engine fitted to the fiesta and ka.
     
  12. roofless

    roofless Senior Member

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    i think the first thing is to go back to basics fuel & spark get it running first to sort any faults then look at the best options for fuel for your car as i am sure the classic mb owners on here will have looked into this in depth & will be happy to help
     
  13. OP
    win230SL

    win230SL New Member

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    No Ignition=engine cranks over until battery dies (if i keep trying.) occasionally as it cranks there is an attempt to run on for about 5 seconds then i have to keep trying but to no avail.
     
  14. nickcc101

    nickcc101 Senior Member

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    Yes would go along with checking the basics first. If it's fuel starvation check the filter is clean and the fuel pump is working ok and you have fuel reaching the engine. If the engine is trying to run it sounds like lack of fuel.
     
  15. keith100

    keith100 Senior Member

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    "(known in the trade as a "crossover")"

    You are too kind Alex - more like a "FU".

    As all have said above, sounds like diesel fuel, or really rotten petrol .

    Wouldn't even 4 star be lead free anyway?
     
  16. nickcc101

    nickcc101 Senior Member

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    Lead free is either SULG or UL, 4 star is the old leaded.
     
  17. meanie

    meanie Senior Member

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    As before,it's probably contaminated fuel.Drain the tank,replace the filter & try again.
    However,it may be worth checking the compressions,as unleaded lacks the volatillity of the old 4 star.I once had an old Astra which would not run on unleaded but ran a dream on 4 star.Just a thought,as these beauties ran a fairly low compression ratio.
     
  18. nickcc101

    nickcc101 Senior Member

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    The only differences between unleaded and leaded is the lead content and the different additives used today. In the old days, if i remember correctly, regular (2 star) was 92 octane, 3 star was 95 octane and 4 star (super) was 97 octane with 5 star (super plus) at 98 octane. ULG is now 95 octane and super ULG is 98. The main reason lead was included was for antiknock purposes.
     
  19. television

    television Always remembered RIP

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    All of these youngsters on the forum, the octane was 40 when I started out
     
  20. nickcc101

    nickcc101 Senior Member

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    Bet you needed lead in those days for your Model T Ford.:)
     

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