Just bought a 2007 Audi B7 S4 that was in an accident and was hit at the front right if you are in the driver seat looking out. I bought it for the engine. I was told that one of the oil lines and oil pan were punctured and was given the specific oil line so I could replace the one that was broken. Engine will try crank, but won't turn over. One time it almost turned over, but failed. Was given a guarantee that the engine is working and doesn't see what it wouldn't because the engine has nothing to do with the accident it was in as they assured me when I bought it with a 20-day refundable purchase. My question is could the oil pan or oil line with a very fast leak be the reason the car does not start. I need the engine to put it in my other B7 S4 and wanted some input on if maybe the fuel pump was hit or if leaking oil(extremely fast as they told me with the oil pan and split hose) would be a reason for it not to start?

  • Not sure why you believe them that the engine was working if the engine still has a broken/damaged oil line and a punctured sump...
    – Solar Mike
    Commented Oct 11, 2018 at 14:48
  • Welcome to Motor Vehicle Maintenance & Repair! Commented Oct 11, 2018 at 16:23
  • Have you already swapped out the engine, or are you trying to get it started in the old car first? Commented Oct 11, 2018 at 16:30
  • No I dont see any reason the engine wouldn't work because the accident had nothing to do with it, but i am trying to get the engine working before i do the swap. Again the damage is on the front right if you are sitting on the inside of the vehicle.
    – Sam S.
    Commented Oct 11, 2018 at 16:54
  • And the oil line and sump arent my concern because they all work in the other car so if need be I might just have to switch some parts to make sure the engine itself works
    – Sam S.
    Commented Oct 11, 2018 at 16:56

2 Answers 2


The engine doesn't need oil to start; it needs oil to not shred itself. (I would NOT try starting a motor without oil). The first step is to check if the motor spins freely: put a socket on the crank pulley bolt and try to spin it clockwise. If it spins freely and smoothly you might not have a grenaded rotating assembly, if it's locked up or extremely jagged then you definitely have a grenaded rotating Assembly.

  • what do you mean gernaded? also i did try probably for a total of 6 or so seconds to start it but i will not until i get the oil replaced. So what could be the reason for it not turning over if you dont mind me asking, for the breef time i tried starting it i did not hear any misfires so the it sounds like all 8 pistons are getting compression and firing, I didnt hear any rattling incase the timing chain was broken, so what else could it be and if it is something is it fixable?
    – Sam S.
    Commented Oct 11, 2018 at 17:17
  • @SamS. - He means "grenaded", but misspelled it. To "grenade" and engine is to "blow it up" or IOW, make it worthless pile of metal. As long as it's turning over freely, I doubt it's "grenaded" but it doesn't mean it is still a viable engine. Check the fuel rail for fuel pressure. Commented Oct 11, 2018 at 17:33
  • Ok thank you for that, it was in an accident, could it also be a crank sensor? it was in an accident and it was hit pretty hard in the front, im thinking maybe on impact the something broke besides the oil lines and oil pan. Cant possibly see how the engine would be grenaded with an accident that just isnt possible in my mind but again im trying to keep an open mind.
    – Sam S.
    Commented Oct 11, 2018 at 17:40
  • If the accident broke an oil line, punctured the sump, and dumped all the oil on the road in about 5 seconds flat, but the driver had other things to worry about apart from stopping the engine (after all, he didn't know yet that the sump was punctured), it might well have stopped itself when it seized solid.
    – alephzero
    Commented Oct 11, 2018 at 18:17
  • Motor running dry before it got to op is the main concern here. It takes nothing more than a few seconds to spin a bearing when there is no oil film to ride. Can you turn the motor over by hand by spinning the crank pulley bolt with a socket? If you cant the motor is bad. If you can the next thing is to compression test. If this tests out good you have a good short block and all other things can be sourced between the 2 motors you now have.
    – DatsunZ1
    Commented Oct 11, 2018 at 18:58

Cars often have a device that detects an impact and switches off the engine in some way (inertia switch). Yours may have tripped in the accident and now needs resetting.

For example - https://goo.gl/images/PsvPPb

This video about an Audi inertia switch may be interesting - https://m.youtube.com/watch?v=fLZQc9SuAc4

  • Thank you that is helpful and will do some more research on that. They did say the engine starts but im not sure I believe that and if It does not im sure its not an issue with the engine, because it had nothing to do with the accident .
    – Sam S.
    Commented Oct 15, 2018 at 13:16
  • But a question for that was I already tried to start it(by mistake) and the engine sounded normal as it should until about three seconds later when it almost started so then i let off the ignition. if i put a socket on the crank pully bolt would that be different then me trying to stat it. also if it is a good engine how easy our hard should it be to turn it with a socket wrench
    – Sam S.
    Commented Oct 15, 2018 at 21:40
  • If it did turn over then it is unlikely to be the intertia switch.Turning the engine by the crank pulley will give a good indication if any major components are damaged. There should be relatively difficult areas to turn as compression builds up and then there should be easier areas when compression is released. The action should be smooth and should be possible with a long wrench without needing to stand on it.
    – HandyHowie
    Commented Oct 16, 2018 at 6:52

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