Mk2 scirocco ABF hot start issues

Discussion in 'Transmission' started by Mk2daz, May 26, 2020.

  1. Mk2daz Forum Member

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    Hi all, I drive a mk2 scirocco that i converted to run a 2.0 16v ABF last year, I'm having some issues with it starting up when its hot.

    It does this about 75% of the time when hot, basically the starter will turn extremely slowly, no where near enough to spin up the engine properly.

    It only ever happens when the car is up to temp i.e. I drive 5-10 miles to the shop, come out the shop and it wont start

    It has an 020 box, and a brand new bosch mk3 gti 8v starter fitted, I have also added an extra earth from starter casing direct to battery -ve but this did not seem to make much difference.

    My next plan of attack was to change the starter motor bush for a new one however I'm not sure if this would make much of a difference.

    Can anyone perhaps shed some light on the situation?

    Here is the car in question

    [​IMG]

    [​IMG]
     
  2. costel1969

    costel1969 Paid Member Paid Member

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    Just to confirm this is only when the car is hot? Does it always start on the first touch when it's cold? The reason I ask is that generally with starters, they either work or they don't regardless of temp. and the fault tends to be something else - example: Fuel pressure not holding, temp. sensor, warm up valve presuming your car has one or the ABF equivalent and as you said you have a new starter in there anyway.
    I'm sure you've checked but is your battery and main leads ok and the right size (amperage) to crank the car - this is a strange one to be honest so hopefully the club brains will be on shortly with some more insight for this.
     
  3. Mk2daz Forum Member

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    Hi, yes this is only when the car is hot, otherwise it will turn over really quickly and fire right up everytime. When i park up at the shops or whatever now i strategically park it on a slope, as it will happily bump start!!

    When it got MOT'd a couple months back the gent at the test centre couldnt get it start after the test either, they even tried a brand new fresh battery, and also jumping it from a beefy jump pack, starter still turned really slowly.

    One of the old mechanics there mentioned something about the engine 'sticking' when hot, something along the lines of that anyway.

    I have read if the starter bush is worn it may cause a slight short if the starter has too much movement or something too.

    As for the battery cables, I have converted it to use the chunkier mk3 terminals and cables, so they should be fine for the job!

    cheers
     
  4. rubjonny

    rubjonny Administrator Staff Member Admin

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    next time it happens put it in third gear and rock the car, see if that makes any difference. our polo used to randomly struggle hot starting and this would get it going.

    when you say brand new, was it a refurb job? and if so, was it a proper bosch refurb or done by a 3rd party outfit who may have used poor quality components?

    the starter bush in the gearbox might be a good plan though
     
  5. Mk2daz Forum Member

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    Thats interesting, I'll give that a try! Is there any reason why that works? :lol:

    As for the starter, i believe it was a refurb job, i did pay good money for it, it had the yellow 'official' bosch tag things on it and came in a proper sealed bosch box etc with all the fancy bosch hologram stickers on it, so I'm assuming a genuine refurb.

    The original scirocco starter done the same thing however, so I'm gonna rule out that the new starter is bad i think.
     
  6. rubjonny

    rubjonny Administrator Staff Member Admin

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    TBH not entirely sure, only thing I know is the problem was solved once I launched it into the nearest bin :lol:

    sounds liek a genuine refurb then so it should be tip top. plus if its done the same on 2 starters can rule that out I think.

    to rule out battery cabling run a jump cable from battery live to stud on starter as well as from the battery negative to the starter body like you already tried. its worth checking the voltage at the battery ignition off and while cranking also, both on a cold start and when its having trouble cranking over. to rule out ignition switch jump a live from starter plug to battery live, but this would usually only affect the solenoid function really as the main motor in the starter is fed direct from battery live
     
  7. Mk2daz Forum Member

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    Okay cool, I'll give it a rock in 3rd next time I'm in that situation!

    Good shout on the battery cabling, I'll give that a try too. I was initially using the sciroccos original battery cabling and it was doing it then too, upgraded to the beefier mk3 cables and added some additional earths to so I'd be surprised it it was the cabling. As for the ignition switch if this was the case wouldn't the starter not turn at all, as opposed to very slowing turning over (and when i say slow, i mean one turn per second slow).

    I will try get a video of it happening next time to make things a bit clearer.

    Can't be too complicated! its just a starter motor with a couple cables running to it, its gotta be something simple! :lol:
     
  8. rubjonny

    rubjonny Administrator Staff Member Admin

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    yeah as i say if it was ignition wiring it shouldnt affect cranking speed really as the actual motor is fed from the battery, just something to try on the off chance.

    battery voltage or starter bush would be high on my list
     
  9. Mk2daz Forum Member

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    Cheers John gives me something to have a look at anyway.

    I just really hope its not the engine itself trying to partially seize or something when hot!!
     
  10. Mk2daz Forum Member

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    Bit of an update on this as I've been kind of ignoring it for the past year and now decided it needs fixed!

    Still having the same issues, yesterday i took a couple voltage drop readings both when hot and when cold

    -ve side im measuring battery negative to starter motor bolt/casing

    +ve side im measuring battery positive to starter motor stud

    COLD

    Voltage drop -ve ~150mV
    Voltage drop +ve ~84mV

    HOT (not stuck)

    Voltage drop -ve ~120mV
    Voltage drop +ve ~80mA

    HOT (stuck)

    Voltage drop -ve ~240mV
    Voltage drop +ve ~180mV

    When the starter is sticking and only turning around once per second my battery 'cranking' voltage is around 9.6V which I believe to be fairly normal?

    Car will happily bump start and the starter will spin freely and as normal when im given a push start.

    Was advised to check my ignition timing however im using the std ABF dizzy which is fixed so i don't think I can do much with that, the ECU should handle all that.

    Have a starter motor bush on order which I will try, but I really am starting to think i have a partially hot seized engine.

    Would a compression test help? When the engine really is up to temp it runs great, pulls like a train...

    Any help appreciated, cheers
     
  11. Mk2daz Forum Member

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    Well this morning I've

    - fitted a brand new starter motor bush
    - made up all new battery wiring from 35mm gauge wire
    - made up a new additional earth lead that goes direct to starter casing
    - cleaned up every earth

    Still not turning over well when hot!!

    When its hot I am able to turn over the engine by hand, its a bit stiff but it does turn over.

    Any ideas anyone?

    Heres a video of what it does...

     
    Last edited: Mar 6, 2021
  12. Mk2daz Forum Member

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    Update

    I let the engine get right up to temp to the point it wouldnt start again, i unplugged the starter solenoid thick red/blk and put a thick (brand new) jumper wire to the solenoid direct from battery +ve, still didn't turn over quick, was just the exact same.

    I've also tried a brand new battery, dad bought one for his van today which is much larger capacity than what i've currently got. But again just turned over really really slowly.


    Done some compression testing too, rough figures with cyl 4 being at gearbox end

    Cold engine throttle wide open:

    1 - 210psi

    2 - 175psi

    3 - 195psi

    4 - 180psi



    Hot engine throttle wide open

    1 - 195psi

    2 - 210psi

    3 - 210psi

    4 - 215psi



    Those numbers seem pretty strong to me for an ABF engine on 180k.

    Oh, and rocking it in gear (3rd) doesn't seem to make much difference either.

    Anyone got any other ideas? @rubjonny maybe? :)

    really not sure what to try now!!!
     
    Last edited: Mar 8, 2021
  13. Mk2daz Forum Member

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    Wondering if I should try a mk2 TD starter for a bit more torque?

    As hot compression readings seem quite high, maybe my mk3 8v starter just isn’t up to it...
     
  14. rubjonny

    rubjonny Administrator Staff Member Admin

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    ok so you've ruled everything out and are left with the starter, next step diesel or td one (not tdi, thats 02a) and see how you go. I never had an issue with my mk3 8v starter but your compression figures are as you say very strong
     
  15. Mk2daz Forum Member

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    Thanks. Am I correct in saying mk2 golf TD starter part no is 068911023GX ?
     
  16. rubjonny

    rubjonny Administrator Staff Member Admin

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    go for the mk3 version, that way it'll have the same mk3 plug on it. can crossref 020911023B, D, P, 020911024AX or 068911023TX
     
  17. Mk2daz Forum Member

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  18. rubjonny

    rubjonny Administrator Staff Member Admin

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    yes those 2 part numbers are 020 mk3 diesel ;) The n/a and turbo diesel ones have 020 box, only the TDI is 02a

    I guess the ebay auction is a generic image, if its for a mk3 golf it should have the proper black plug housing on it
     
  19. Mk2daz Forum Member

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    Thanks John, I've went for the one I linked above, it says 'plug style ID - plug' so hopefully it will have a mk3 plug!

    They list the diesel ones as 1.8kW where as i think the mk3 8v one is 1.1kW... hopefully this does the trick.
     
  20. Mk2daz Forum Member

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    Well fitted the mk3 1.9 diesel unit tonight, its a fair bit bigger than the 8v petrol starter!

    It spins the engine up a lot quicker and sounds totally different

    Gave the car a good thrash around till the engine was nice and hot, then was able to start the car up about 10 times in a row hassle free.

    Fingers crossed...!

    [​IMG]

    [​IMG]
     
    costel1969 likes this.

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