300tdi knocking & now wont fire

Morning people I have a 300tdi. Last night the Mrs took it for a 40 mile round trip 2 miles from home she said it started knocking when she arrived home she left it running and it was running as rough as you like extremely lumpy. Once it was switched off it will not fire again.
Now the disco has only been back on the road after extensive work including timing belt replacement with the modification. When I first purchased the car the timing had slipped and it would not fire. I am thinking this could have happened again but the modification has failed as after doing a search I have read this has happened before.
Failing that if the vac pump has packed up would this then stop the oil pump functioning.
Any help much appreciated, will be tearing it apart later today so I will keep you posted.

brake servo will not have anything to do with it as it is cam driven and the oil pump is crank driven, got to be the timing belt

it does sound like belt slipped a little to start with whilst engine was running, then shifted a lot when it was turned off, due to dissimilar momentum between top and bottom of engine, hence it now won't start.

kernowdragon said:

it does sound like belt slipped a little to start with whilst engine was running, then shifted a lot when it was turned off, due to dissimilar momentum between top and bottom of engine, hence it now won't start.

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crikey !

I know I started this thread time ago but here goes!!!! Stripped the timing cover off to find the stud for the tensioner had failed and stripped the thread right out of the cover hence timing belt had tore itself to pieces.

Have replaced and and made good all of the above timed it all up, rotated engine by hand with no rocker in it and it goes over fine. The minute I put the rocker back in she will not turn over. I have put 8 new push rods in and also had the valves out and they all look fine be it a bite coked up. Anyone have any ideas where to go with this other than burning it cause thats the first thing I came up with lol. Thanks in adavance Ross.

slacken tappet adjusters ,twist rods to make sure seated in socket,check timing crank ,cam,

So it wont turn over with the rocker shaft fitted??

Can you re-check the timing as it sounds like a valve is hitting a piston.

Morning James. The timing is defo spot on, and the crack and cam are intact and as should be, but I shall try slackening the adjusters thanks very much for your suggestion.

Hi Dave after fitting the new timing belt I removed all the pins and rotated the engine 3 maybe 4 times by hand and the marks all lined up again. There is no visible sign of the valves kissing the top of the piston. The only signs on the top of the piston was of crap glow plugs where the tips had burnt off.

Ok, good, then as JamesMartin said, slacken off all adjusters and reseat the rods then set clearances.

Hopefully that'll get her going again.

I had a similar if not quite so extreme issue when she'd lost a valve cap on the rocker assembly after a head job, this wil become apparent after you slackened and checked your rockers clearances, good luck