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HELP: Unknown engine failure after starter motor fire (B8.5)

Garagista Feb 19, 2019

  1. Garagista

    Garagista Registered User

    Hi All, Well this is a first post. I've perused this site for a long time and purchased my S5 on the back of a lot of what is said, and what is not said about the S5. Such as the engines are bullet proof.

    I have a late 2014 B8.5 S5.

    So my issue is as follows:
    I was driving down the motorway and had to brake for a van moving into the third lane as I was passing. I didn't have to brake hard but it felt as though the ABS kicked in.
    He then didn't pull out so I went to go pass again and lost power. Checked the rear view and saw smoke, so pulled over to the hard shoulder turned the engine off and came to a stop.
    Strong smell of electrical burning so left the bonnet open and walked away - expecting to dial 999 for a fire engine and not the AA.
    4 hours later was picked up by the AA. I put the electronic hand brake on when I had stopped on the motorway but it wouldn't come off in order to move the car onto the low loader. A few pushes of the start button (without foot on brake) and it disengages. I leave it in neutral and it gets pulled onto the back of the truck.

    Drop it off at an Audi specialist garage, who find the fire damage to where the main earth wire and starter motor power cable are fastened to the body. That had burnt the regulator in the alternator. The other seat of fire was the solenoid of the starter motor.
    Both of which self extinguished.

    The garage has replaced the parts and put the car back together and said that when they started it, the starter motor worked but the engine essentially turned without resistance.
    They'd hand cranked it on day 1 (were now day 33 due to wiring loom needing to be made and the alternator being on a 10 day back order) and found no issue.

    There is no oil splatter anywhere, and wasn't on the motorway when I stopped. No loud bang, clang or anything like that on the motorway, just as though the ABS clicked once and that's it.

    They've called and said I need to come and listen tomorrow but I'm very confused.
    I used to be an automotive engineer (manufacturing) so understand most things. I've changed gearbox's, clutches, exhausts, suspensions etc etc. But the nearest I've been to tinkering with an engine was my sons Haynes DIY engine build which he did age 5.

    I believe it has compression as there's no reason to believe otherwise. The pistons move freely. How is it that the pistons can move up and down without generating pressure and turning over?
    Every valve open? I've no clue.

    Stupid me spent every penny I don't have to get this bullet proof car only to have this failure 5.5 months in. So there is no money to throw at it.

    Don't get me started on the useless warranty I paid for.

    Anyone got any ideas on what might be going on with the engine?
    Last edited: Feb 19, 2019
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  3. Garagista

    Garagista Registered User

    Went to the garage, they tried to turn it over with me there and, nothing. A click, a sound of relays flickering but the starter motor wouldn't spin. Then came an electrical burning smell again so battery out again.

    Mechanic thinks somehow the engine is ceased and needs investigating internally to get to the bottom of it.
    He added that when they turned it over for the first time it span (presumed without compression) 'clunked' and stopped. Again, they've no idea what has happened or why.
  4. MuPPeT_ON_TouR

    MuPPeT_ON_TouR Registered User

    I only wish I could help but have no real idea of what could be wrong.

    But it sounds like more electrical gremlins than a mechanical failure. The engine's not seized, no expensive sounding crunch noises. My guess is an electrical issue that ment no spark to start the engine.

    I think the fire has damaged much more wires.

    Horrible to think that a full fire would have been better in this case, it would have ment a write off and insurance payout. Rather than what you face now.

    Good luck.

    Perhaps move this to General automotive? More people will see it and I don't think this is a specific S5 issue.
  5. RAF_S7

    RAF_S7 Well-Known Member Gold Supporter

    Later model Audi's are quite complicated beasts when it comes to electrics.

    There are a number of fused links that carry power from the battery to various parts. Has your garage confirmed all fuses/fuse-links are intact?

    Also, has the starter been confirmed as fully serviceable?
  6. Garagista

    Garagista Registered User

    I thought that about the fire today. It would have been traumatic but far less problematic.
    (If there's an admin watching who could help move it to general automotive that would be great)

    That's a good question about fuses - especially as it makes more sense to me than a mechanical failure as I know I turned it off, and I am also sure that the surge that caused the fire would have tracked back up the 0v line hitting who knows what. I don't think they've checked or at least they've certainly not told me. I had asked to down tools on it but I need to collect the child seat and other bits tomorrow so I'll ask about the fuses then.

    The starter motor was ordered new but I also wondered (given the luck I've had with this car) whether it was another bad part.

    Thanks for the replies.

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