ticking noise - help greatly appreciated!

My 2.5 N/A is making a noise that I haven't been able to troubleshoot. Thanks in advance for any help...

- The engine is relatively new (less than 3,000 miles but a little over 1 year old, so unfortunately out of warranty). It ran well without any abnormal noises for the first few thousand miles.
- It has never overheated and oil pressure has always been normal.
- The noise starts as soon as I start the engine, and it gets louder as the engine heats up to operating temperature. It increases frequency with RPM to the point where driving it makes it loud enough to hear in the cab with the windows up.
- It's a consistent, rhythmic "tick tick" that seems to be coming from the rear of the block (fuel lift pump area) when I use a stethoscope. It seems to happen on the 5th and 6th beat of the normal rhythmic noise coming from the fuel lift pump rocker arm.
- I put in a new fuel lift pump, but the noise didn't go away.
- The rocker arm on the old pump was loose (had lateral play that the new one didn't have). When I first inspected the old pump, I was sure that would be the problem...big disappointment when the noise was still there.
- The valves have been checked (torque settings and for any damage or abnormalities) and are good to go. They're also relatively quiet when checked with a stethoscope.
- The fuel injectors have been checked and are fully operational - they correctly squirt fuel, don't leak and sound normal.
- The oil pan has been dropped to check for anything in the oil and for cylinder liner migration - no metal/coolant/etc. found in the oil and the liners check out.
- The engine output is great, there's no smoke (other than a bit of normal white smoke a few second after start-up), and it doesn't vibrate abnormally. The sound is the only odd thing.

Could it be the gear on the crank that actuates the lift pump rocker arm? Could it be a crank bearing? Flywheel torque?

Any insight is tremendously appreciated!

Thanks!

check you glow plugs to see if its loosing a bit of compression through the centre of them could also be exhaust manifold blow .

think you can manually adjust valve clearances on the 2.5 are they adjusted correctly?

If it were a 200 or 300, I'd say vacuum pump, dunno bout N/A injuns though.

head gasket's very common on the tdi's especially at the back which makes a sort of tick, dunno about the n/a.

first thing I'd try is valve clearences, then I'd be looking at that fuel pump drive gear....

Thanks for the replies, everyone! The valve clearances, the vacuum pump and compression all check out. I think it'll be time for me to check the fuel pump drive gear.

I checked in my workshop manual, and there's nothing at all mentioned for this procedure. I'd like to do as much inspecting as possible before taking out the engine. I assume that the drive gear can be inspected by dropping the oil pan. What's the best way (if at all) to advance the crank with the oil pan off so I can inspect all of the gear? What else besides worn gear teeth should I look for?

Thanks again!

Had the same with my 2.5 N/A it was a rattling hot spot which then fell out and went through piston 3 cheers ian.

i would check cam followers and guides not fuel pump drive gear as there isnt one ,guides can wear causing brass follower to stick or locating bolt on out side of block come loose,check 8 x bolt .remove rocker box feel each rocker arm whilst running use screw drive etc to feel notchiness