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Thread: Wont start after engine rebuild

  1. #1

    Wont start after engine rebuild

    Hi Everyone

    I have just rebuilt a 1.4 AUA engine and fitted it but it wont start for some reason and I cant seem to find a plug going onto a sensor just above the driverside driveshaft, I cant find the wire anywhere but wouldnt have thought it would be preventing the engine from starting ?? There is spark and fuel but no start ???

    Can anyone help please maybe I have forgotten something ???

    Just to note I rebuilt the engine because the thrust washers had fallen out and made a mess of the crankshaft and blocks, so I replaced both crankshaft and fitting blocks.

    Thanks

  2. #2
    Join Date
    Apr 2009
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    Staines, Middlesex, UK
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    12,329
    Are you sure that the cambelt timing is correct.

    Another thing to check is that your immobiliser is not the cause.
    This is unlikely because it would fire up but die instantly and you would get the red car/key light in the dash.

    Steve B
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  3. #3
    I'm 100% sure I got the tdc right with the notch on the crank shaft and alighnment of the two top ones with a strait edge,

  4. #4
    the sensor on the back of the engine is the knock sensor , possibly without this connected the engine wont run , as for timing the engine , you can push 8mm drill bits into the holes in the cam pulleys to lock them to correct position as theres locating holes behind the pulleys machined into the cylinder head, if the timing is the slightest bit out they dont start ...
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  5. #5
    Join Date
    Oct 2016
    Location
    Saltash, Cornwall, UK.
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    To repeat the above, alignment of the top end is not with a straight edge but by locking the cams. You need a tight fit and I’ve found 1/4” extension bars to be a perfect fit. The belt also has to go on anti-clockwise so the tensioner takes up the slack of the belt without adjusting the timing.

    A couple turns by hand and checking the alighnment pins fit in the top end and the timing mark on the crank all line up and your good to go.

    If you’ve got fuel and a spark, she should start.
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  6. #6
    Quote Originally Posted by JIGSAW View Post
    the sensor on the back of the engine is the knock sensor , possibly without this connected the engine wont run , as for timing the engine , you can push 8mm drill bits into the holes in the cam pulleys to lock them to correct position as theres locating holes behind the pulleys machined into the cylinder head, if the timing is the slightest bit out they dont start ...
    I'm pretty sure the timing is ok as i hand turned the engine several times and everything lined up as it should, and I didnt mean the knock sensor on the back of the engine, one above the driveshaft

  7. #7
    theres also one that goes to the flywheel and is crankshaft position sensor in the same area, and for sure if thats not connected it wont run, from memory the sensor located against the flyheel by the cranckshaft and has a long cable attached to the sensor and where it plugs into is the other side by the oil seperator cambelt side of the back of engine
    Last edited by JIGSAW; 04-10-2017 at 09:27 PM.
    Audi A2 TDI SE , Working sky , Bose , Dis , rear electric windows , Red leather .... Daily Driver

    Audi A2 1.4 16valve

    AUDI A2 SE 1.4TDI dirty diesel dog, Rebuild in progress , next stage custom stainless manifold and VNT Turbo

    Project A2 Quattro Twin bike Engined Transplant, custom paintwork, bodykit front and rear bumper update with A6 sport Grill .

  8. #8
    I did lock them and align them :-( this is why I'm confused

  9. #9
    you can see the crankshaft sensor and the knock sensor in this photo and may help you

    Click image for larger version. 

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    Audi A2 TDI SE , Working sky , Bose , Dis , rear electric windows , Red leather .... Daily Driver

    Audi A2 1.4 16valve

    AUDI A2 SE 1.4TDI dirty diesel dog, Rebuild in progress , next stage custom stainless manifold and VNT Turbo

    Project A2 Quattro Twin bike Engined Transplant, custom paintwork, bodykit front and rear bumper update with A6 sport Grill .

  10. #10
    Join Date
    Aug 2015
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    I am sure if the knock sensor is not connected it will not run - knock sensors cuts injectors
    Also if the crank sensor is not connected it will not run - does not know where TDC is, therefore when to inject and spark
    Paul (Depronman)
    1.4 TDI 2001 287,347 miles and still going strong

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