Defender 200tdi tapping noise

Recently I fully rebuilt my 200 engine which runs as sweet as. No smoke whatsoever or leaks which is surprising. However I have a fairly loud tapping noise which appears to be coming from centre, lower front of the engine.
Myself and a landy builder have had the stethoscope on trying to locate it but no obvious location.
The strange thing is it doesn't start straight away on start up when cold, takes about 5 mins to materialise. The sound appears to be half engine speed (t-belt/cam speed) not full crank speed.
What is even more strange is that when I drive on an incline the noise stops, go back on the flat and it's back. I have disconnected all ancillaries including the viscous fan. No change. After some research I was inclined to think the timing belt tensioner pully may have been at fault so I spent yesterday stripping down and replacing it. Timed it up and ran it without front cover for a few mins and the noise wasn't evident but as I said it wasn't ran for long.
I am now down to brain matter after scratching my head over this so new ideas are very much welcomed and needed.

if its 1/2 crank speed it wont be timing belt it has to be cam, followers ,tappets etc or something driven from cam, could something have dropped in cam gallery whilst you had engine apart,has head been skimmed is a valve just touching a piston

As far as I'm concerned nothing could have entered the engine because I was so meticulous in cleaning and reassembly that I'm 99% sure of that. Plus there were no 'spare parts' left over.
As for the head, no I didn't have it skimmed because it is on a 3 hole gasket and had no previous head related problems, I just re seated the valves and replaced the valve stem seals. It was the block that had most of the work done, re bore, re grind etc.

have you checked all the cam follower guide tube locater bolts, block face skimmed ?piston height measured

Been out n checked. All the bolts are in tight and thread locked. The firm I had bore the block never mentioned having the block skimmed but I did check both head and block face for level with ruler and a light behind but appeared as good as shining a lithe behind a straight edge can be.

What I don't get is regardless of the cause why does the noise completely stop on an incline? Surely if it was piston/crank or clearance issues it would be there all the time...

D.G.F.S. said:

Been out n checked. All the bolts are in tight and thread locked. The firm I had bore the block never mentioned having the block skimmed but I did check both head and block face for level with ruler and a light behind but appeared as good as shining a lithe behind a straight edge can be.

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it was piston height i was thinking of

I see where you're coming from but correct me on this, the crank and pistons move/rotate the same path every stroke, no variables apart from heat expansion. The gap between the crown and c-head are fixed and consistent so if the piston was fouling a valve or whatever then it would do it even if the engine was on its side or upside down right?

D.G.F.S. said:

I see where you're coming from but correct me on this, the crank and pistons move/rotate the same path every stroke, no variables apart from heat expansion. The gap between the crown and c-head are fixed and consistent so if the piston was fouling a valve or whatever then it would do it even if the engine was on its side or upside down right?

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you wouldnt expect going up a hill to effect it ,temp quite likely,id probably start by removing rocker cover and go from there

Ive seen a few pics over the years where the roller tappet had flat spotted, this same fault also happens on the trucks, worst is when the little securing bolts shears the pin part off and allows the whole assembly to rotate and the tappet roller chews up the camshaft.

lynall said:

Ive seen a few pics over the years where the roller tappet had flat spotted, this same fault also happens on the trucks, worst is when the little securing bolts shears the pin part off and allows the whole assembly to rotate and the tappet roller chews up the camshaft.

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its not uncommon with some of the cheaper parts, ive seen it a few times

Weirdly Ive never seen it myself on the land rovers and Ive had a few tdis.
I can remember a post on the series 2 forum where two guys spent ages trying to track down intermittent noise on a 300 and it was the roller flat spotted.
Trucks its catastrophic as its gearbox and rad out for access to change cam!

When I re assembled I cleaned all parts before fitting and the rollers were as round as I'd expect them to be but with what you and James say it's looking cam related. As for having rocker off, I set the tappets last Friday nite because they were noisy and I was hoping they may be the cause of the noise but nope. As I write this I'm sat in the landy on tickover on a slight hill and no noise again... Until I move. When listening outside for the noise, it appears to be t-chest though, it's at its loudest level with the radiator/crank pulley but I know that noises aren't always where the fault is. When using the stethoscope there was no significant noise anywhere along the cam side of the engine or timing chest.

lynall said:

Weirdly Ive never seen it myself on the land rovers and Ive had a few tdis.
I can remember a post on the series 2 forum where two guys spent ages trying to track down intermittent noise on a 300 and it was the roller flat spotted.
Trucks its catastrophic as its gearbox and rad out for access to change cam!

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Well at least it's not as a drastic issue for the tdi then!

lynall said:

Weirdly Ive never seen it myself on the land rovers and Ive had a few tdis.
I can remember a post on the series 2 forum where two guys spent ages trying to track down intermittent noise on a 300 and it was the roller flat spotted.
Trucks its catastrophic as its gearbox and rad out for access to change cam!

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last one i had was last spring in a 2..5 na,roller looked like it hadnt been in too long ,luckily it hadnt damaged cam lobe.previously it was usually the brass follower that failed ie rod punching through locating cup

its worth checking when you set tappets that all the adjuster have a similar amount of thread above the nut

Ok well for the sake of three bolts and a breather I will check that. Landy mates keep saying let it develop and I'm almost inclined to agree however I've invested a lot of time and money into the rebuild for something to go tits up now.

And thanks for your input, will keep you posted on my findings/developments.

Well then... After much prodding and poking and prying the problem appears to be excessive end float. I have no bloody idea why as the washers were new and fitted correctly 300miles ago.
I've been doing some research but can't find a definitive answer as to whether or not I can replace the thrust washers in situ, can anyone advise me please? Cheers.

end float on the cam ?