General question about jump starting

Discussion in 'General Motoring' started by troubleinstore, Jan 11, 2005.

  1. I have been told that the more modern cars do not like to be jump started,
    but the person who informed me of this could not give me any reason for
    this.

    Is it true and more importantly, why.....?

    If you have a flat battery, then the raodside breakdown companies like AA
    and RAC jump start cars...!
    --
    troubleinstore
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    troubleinstore, Jan 11, 2005
    #1
  2. troubleinstore

    Terrytubby Guest

    troubleinstore <> in
    typed something a little like this (allegedly):
    Think it may have something to do with the cam belt and the load you put on
    it causing it to fail or weaken, but I could be wrong.

    As for the AA and RAC, I have never seen this. I have only seen them use
    jump leads.
     
    Terrytubby, Jan 11, 2005
    #2
  3. Gents
    Modern road side mechanics will not BUMP start cars for fear of braking the
    Cam belt. This could be what you mean.
    Mike
     
    MICHAEL ROCHE, Jan 11, 2005
    #3
  4. troubleinstore

    Malc Guest

    Apart from the obvious safety aspect of a car suddenly starting or trying to
    bump start on the hard shoulder. Why would bump starting affect the cambelt?
    It surely can't be much worse than the starter motor can it?
     
    Malc, Jan 11, 2005
    #4
  5. troubleinstore

    John & Frank Guest

    Think we are confusing JUMP start with BUMP start, which are of course two
    different things.

    You can jump start a modern car with no problems, as long as you make sure
    you get the leads the right way round first time!

    You CAN bump start a modern car (Im assuming a flat battery) but its not
    recommended because of things like:

    The fuel injection system has to be pressurised, which takes 12v power to
    run the pump, making it harder to bump start (cos you have to push longer
    when in gear lol)

    Catalytic converters dont like jump starting, cos you can get unburnt petrol
    into the cat, which I understand can reduce the life of, or ruin the cat

    Think thats the main reason. Im sure a few petrol heads will add a few
    more.

    Oh I have a question..

    Can you BUMP start a diesel car??

    John.
     
    John & Frank, Jan 11, 2005
    #5
  6. troubleinstore

    Nik&Andy Guest

    Yes you can bump start an older diesel(turbo or not) car, as long as you
    have enough electrical power to turn on the fuel stop solenoid.

    Of course a modern PD-TDI or HDI with electric injectors would be a
    different matter I guess.
    My other car is a VW Touran, 140hp 2.0 16v PD-TDI - It says in the manual
    NOT to try bump starting, but does not give a reason?

    Andy
     
    Nik&Andy, Jan 11, 2005
    #6
  7. Gentlemen, above I asked about JUMP starting, not bump starting ..... ! i.e.
    using leads from the battery of one vehicle to the battery off another

    --
    troubleinstore
    Email address in posting is ficticious and is intended as spam trap
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    troubleinstore, Jan 12, 2005
    #7
  8. troubleinstore

    Nik&Andy Guest

    Assuming the Jump start is done correctly, connecting the earth to the
    engine, not the battery, I cannot see any reason why not to Jump start.

    Andy
     
    Nik&Andy, Jan 12, 2005
    #8
  9. Just check the manual. Some of the newer cars have such delicate ECUs that
    they may not be jump started.

    IPG
     
    Ívar Pétur Guðnason, Jan 12, 2005
    #9
  10. troubleinstore

    Nom Guest

    He has got confused.

    Modern cars don't like to be BUMP started - partly cos the injection system
    won't work without power, and partly cos the Cat doesn't like it.

    JUMP starting is fine. Providing it's done properly, it's exactly the same
    as starting the car from it's own battery - it obviously doesn't care where
    the power is coming from !
     
    Nom, Jan 12, 2005
    #10
  11. Something in the back of my mind reckons that some ECU's prefer it if the
    two cars remain connected with the engines running for quite a while or
    there can be problems with the receiving one. I am not entirely sure if
    this is true or not, maybe someone who really knows could enlighten us.

    Ron Robinson
     
    R.N. Robinson, Jan 12, 2005
    #11
  12. troubleinstore

    Fitzy Guest

    Jump starting with leads,,,, Just make sure the ignition on the receiving
    car is turned OFF,
    Fitzy
     
    Fitzy, Jan 12, 2005
    #12
  13. troubleinstore

    Carl Gibbs Guest

    Mines (205DT) been bump started and jump started before :)
    However they are harder to bump start becuase of the higher compression
    ratio. Wouldnt like to try bump starting it when cold at this time of year
    though!
     
    Carl Gibbs, Jan 12, 2005
    #13
  14. Presumably you mean when disconnecting, in which case the cars would have
    had to stay connected long enough to put a useful amount of juice in the
    receiving battery so that it can restart its car. Unlike old-fashioned
    systems where you just start the receiving car and whip the leads off as
    soon as it is running (donor end first if you haven't connected the earth
    lead well away from the battery)

    Ron Robinson
     
    R.N. Robinson, Jan 13, 2005
    #14
  15. troubleinstore

    JC Guest

    Once the engine is running on the car needing the jump start, you can
    disconnect the leads however you like, no need to turn off the car to do
    this (however modern the car) as there will be power in the system, albeit
    very little, but enough to keep the engine going.

    A much easier trick is just to rev the jump start recieving car so that its
    charging faster while your mate disconnects the leads (safely, of course),
    worked on my mates HDi!!
     
    JC, Jan 13, 2005
    #15
  16. troubleinstore

    Fitzy Guest

    providing the alternator is charging the battery, then the engine should
    keep running after jump leads are disconnected, as "JC" has already said,
    I would advise disconnecting the earth lead (black) first though,
    its considered safer,,, if you accidentally drop it on the engine or body,
    it wont short out, but the live (red) if dropped will short and do damage,

    Fitzy
     
    Fitzy, Jan 14, 2005
    #16
  17. troubleinstore

    Fitzy Guest

    Quite right there Malc,
    With the key,,,,,,,,,,,,,,
    Starter turns the crankshaft,, crankshaft turns the cambelt,

    When car is push started or bump started ,,the wheels turn the gearbox the
    box turns the crankshaft via the clutch,, the crankshaft turns the cam belt,
    so you are right,,,,,,,,, no different
    HTH
    Fitzy
     
    Fitzy, Jan 15, 2005
    #17
  18. troubleinstore

    Taz Guest

    I've found that a tow start is easier on a diesel.
     
    Taz, Jan 15, 2005
    #18
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