TD5 engine screeching under acceleration

My 2001 TD5 has started to screech slightly under heavy/prolonged acceleration. The noise is not present when travelling at a constant speed.

I was thinking it might be the timing chains, does anyone know of anything else I should be looking for?

Thanks!

Hi
Have a look at the crankshaft pulley, my brother had an issue of a screeching noise on his Td5 when accelerating, turned out the pulley had broken up.
I think from memory there was a video on YouTube of one so you could try searching it and compare noises.

Also if you could record the noise and post it would be a great help in order to try identify the cause

blowing exhaust manifold gaskets can make similar

exhaust nuts sheared as James points out above

Thanks everyone - I'll dig around and investigate the suggestions that have been made.

Could it be as simple as a slipping aux belt or worn pulleys. Take of the belt and check your idler pulley and belt tensioner pulley by spinning quickly, you'll know if they've worn out by the noise/ movement. Easy to check and replace, check the belt for wear also.

I strongly suspect that it will be the exhaust manifold blowing. Is the engine remapped?, this can make them very susceptible to this, the exhaust manifold warps with the increased engine temperature then breaks several of the mounting studs causing the screech by way of escaping exhaust gas.
Simple check, look under the heat shield above the turbo and exhaust manifold on the right side of the engine as you look at it from the front.
Are all 10 nuts present on the exhaust manifold? Is there signs of soot around the joint?
If so then im afraid its the manifold. This has happened to me twice, hopefully now cured. The first time the manifold was replaced with a second hand one from a breaker and the broken studs replaced. It lasted about 2 years then same again. I decided that I wanted a permanent fix and did a bit of research about it. There are loads of threads and opinions on the best way to do this. Pricey tubular fabricated manifolds, ceramic coated manifolds to help the heat from warping it, cutting out the webs on the cast manifold etc etc. What I have done is bought a secondhand manifold that previously warped but which has been skimmed on a milling machine making it true again. The generally accepted wisdom is that once it has been heated to the degree that it has warped that the molecular structure has changed permanently and further heating at similar temperatures will not affect it again (some may disagree?). Then it was fitted with an uprated stud set from JE Engineering which provide a better clamping method. So far so good. I put my warping down to 1, remapped engine - provenance unknown as it was done before I got it and 2, long towing at motorway speeds with a big twin axle caravan.
Hope you get to the bottom of the problem!