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  1. #1
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    1.8T rebuild....now not starting!

    Hi there,

    I'm having a bit of an issue with my brothers 2001 1.8T A4.

    Breakdown
    Whilst driving at a steady speed on the motorway his oil warning light came on. He stopped immediately and checked the oil level which appeared ok. He let the car cool for 30 mins and then bravely! started it up and re-continued his journey, the oil remained off for a further 30 mins and then came on again. He pulled off the motorway and into a service station and as he was slowing to stop the engine stalled and cut out. The oil level was rechecked and again looked ok which would suggest a sludge issue resulting in oil starvation.

    Rebuild
    The car was dropped at my house by the recovery vehicle and I immediately pulled the engine for inspection. When stripping down I found all timing marks were where they should be. The sump was very sludgy and all 8 exhaust valves were bent.

    I replaced the valves and did the big end bearings while the block was on the stand. There was no visible signs of bore or cam lobe wear therefore I left alone.

    The engine was refitted and timed up with a new belt tensioner and damper.

    Starting up

    When starting for the first time the starter appeared not to turn the engine properly (see video link below), which suggested there was an issue with the starter however I have removed and tested the unit and it was fine. I did notice once the starter was out that there appeared to be a score mark on the flywheel and the sandwich plate between the box and block appeared to be touching the fly?? I refitted the starter and slackened the gearbox bolts in case the box and block were not seated correctly but no difference was seen.

    I have checked the starter voltage when turning and it's fine at 12v, I have also earthed the negative terminal to the chassis using a jump lead in case of a bad earth but no change.

    I removed the plugs and turned the engine over by hand at first and it seemed ok to turn until it got to TDC when it tightened up and then after TDC was easier, which I would assume is normal. I turned the motor over on the starter without the plugs fitted and the turnover is still not right suggesting lack of compression?!?

    I removed the cam cover to check the cam timing marks had 16 rollers between and noted that I had only 15.

    Is it possible that the initial problem that bent the valves in the first place was the low oil pressure causing the cam chain tensioner to fail and thus bending the valves? I'm concerned that the new valves I have fitted now also bent as the cam timing is out?!?

    VID00012-20110205-1132.mp4 video by kaiser_solsay - Photobucket


    Any thoughts?

    Cheers,

    Dominic

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  3. #2
    "Stick a V8 in it!"

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    given you suspected oil starvation, did you actually check the main and cam bearings for wear?

    Did you replace the piston rings?

    Did you check the timing sprocket had not snapped its woodruff key and hence moved in relation to the crankshaft itself?

    Edit: having watched your video i can say with almost certainty that you have no compression there, which probably means bent valves.
    Last edited by aragorn; 7th February 2011 at 14:17.

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
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  4. #3
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    Checked the bearings and all ok. I didn't replace the rings as ok. I didn't check the timing sprocket woodruff key, is it possible to check without taking off my belt? I don't want to ruin my timing belt damper as last time I removed the belt I had to buy a new damper as I couldn't get the damper piston to retract.

    Crank and cam timing marks are spot on the only marks that are not are the roller timings on the cam chain. Instead of seeing 16 rollers there are 15.

    I have ordered a compression gauge so will check ASAP when it arrives in the next few days. I'm not sure what would bend the valves again as all timing marks are spot on. I'm thinking the cam buckets are not filling with oil and valves are not opening properly. What that cause poor compression?

  5. #4
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    Well the 15 rollers instead of 16 will more than likely cause the lack of compression so that will need sorting first and foremost. Once it is sorted then you will need to perform a compression test so see if any more valves have been bent
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  6. #5
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    that engine has no compression. I would check that pulley like i said over on SRS

    line up the timing marks again and check TDC manually . Then undo the big bolt in the centre of the bottom pulley. I bet the bolt is slightly loose and the pulley has sheared the key sadly

  7. #6
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    Carried out a compression check this evening and got zero reading from all 4 cylinders....gutted! Not sure what's gone wrong as the valves were ground into their seats and the engine timed. The only thing I can think and as someone has suggested on another forum, the woodruff key in the cam sprocket has broken which was the original cause for the breakdown. I hadn't removed the cam sprocket so didn't check.

    I'll need to remove the head and inspect. How do you remove the cam belt without knackering your belt damper? The last time I removed the belt I couldn't get the belt damper piston to compress and ended up bending the tensioner.

  8. #7
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    Thanks.

    I've timed the motor back up before removing the head and noted the position on the marks on the cams. Both inlet and exhaust cam marks are completely out despite the cam sprocket mark and cranks marks being bang on. Looking at both marks on the rear of the cams they are both out of time equally which strikes to me that the front cam sprocket has somehow loosened and thus bending the valves.

    See pics below of cam timing marks...both are 2 chain links out to the left. I bit hard to see in the pics but you can just make out the cam marks.


    [/img]

  9. #8
    "Stick a V8 in it!"

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    If you didnt touch the cam chain it wont have moved.

    The problem will be the woodruff key on the crankshaft pulley.

    the key shears, meaning the pulley no longer sits in the correct position with relation to the crankshaft.

    The camshaft pulley also has a keyway, but i've never heard of these breaking.

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
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  10. #9
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    The crankshaft pulley is solid though with no sign of movement. When I turn it over with a socket and power bar there is absolutely no sign of it moving. I did notice however that the cam sprocket bolt did seem too tight.

    The crank bolt is obviously extremely tight to remove....any tips on how do you slacken? If it is the woodruff key is it just a simple replacement job.....or is the crank fcuk'd?

  11. #10
    "Stick a V8 in it!"

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    I think its part of the pulley, so you'd just need a new pulley, as well as another set of replacement valves.

    If you suspect the cam sprocket then pull that off too and check it.

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
    2000 A4 1.8T Sport Quattro Saloon, Black-ish
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  12. #11
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    Any tips on slackening the cam pulley bolt without the special tool? Grips on the cam??

  13. #12
    "Stick a V8 in it!"

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    you can make your own tool using some lengths of bar and some large bolts.

    2000 A4 1.8T Sport Quattro Avant, Berry Pearl
    2000 A4 1.8T Sport Quattro Saloon, Black-ish
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  14. #13
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    Just thinking.....no 1 piston sits at TDC when the crank pulley is lined up to the mark, surely this mean that the crank woodruff key is spot on? Would it not be more the case that the cam sprocket is duff? I'm going to try and crack the pulley bolt off tonight and examine.
    Last edited by kaisersolsay; 12th February 2011 at 18:41.

  15. #14
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    have you managed to sort car yet ?.

    brother in law has a 99 plate a4 1.8t

    called in other day and said he had a oil pressure warning on . 24 hours later car is dead

    had a quick look today car turns over and has very little compression , also seems to be blowing back from the 4th cylinder into the 3rd .

    i suspect the oil pump has failed causing the timing chain to slip and bending the valves.

  16. #15
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    Hi there,

    Not quite sorted yet. I've got a 2nd hand head coming so will fire that on but this time double check the cams are properly timed. I'm still not entirely sure what caused the cam chain to jump however I'm positive the blocked oil pick up pipe in the sump caused the flashing oil warning light prior to the breakdown. I just don't know what exactly mechanically caused the chain to skip.

    To save yourself a lot of time line up the timing marks on the crank and cam pulley and then whip off the cam cover and check if the notches on the rear of both cams line up with the arrows. My bet is that they are out like mine by 2 or 3 chain links which will inevitably mean bent valves.

    Removing the head is actually quiet simple and quick even if you haven't worked on an Audi engine before. Let me us know how you get on.

  17. #16
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    Update

    I replaced the head and started her but the bottom end is knackered. Chap chap chap!

    I stripped down the motor today in preparation to lift out and replace with a complete 2nd hand motor but I noticed quite a lot of oil in the boost pipes considering they had all been cleaned and the car only driven a few miles.

    Would this suggest the turbo is away? There's no play in the shaft.

  18. #17
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    It's possible the bores were US and the blowby caused the PCV system to back up. Or the oil seals in the turbo went when the oil pump gave up

  19. #18
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    Ok so I'm as well getting a 2nd hand motor with turbo then. Can I run a K03s without any ECU remap? Is there a benefit?

  20. #19
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    don't forget the transverse turbo won't fit. You will need a longitudinal turbo.

  21. #20
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    ah...ok....so Golf 1.8T motors wont fit then?

 

 

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