2.2 tdci engine block 2007 mk7

[Cellutron]

Hello
Currently I am rebuilding the engine. Engine had been running dry due to gunk. On complete strip down, found cyl. 3 piston and bore chewed up.had a new liner fitted, honed, and skimmed the top. Found it quite expensive,£300 just that! There seems to be only 2 machine shops in Bournemouth area, so not only it took weeks to do the job, but the fees are higher as well!
So far spend days cleaning the block, then found what looked like an 'o'ring in the front main bearing oil hole, asked the machine shop who said it might be the gunk solidified. Tried screw driver to pull it out. Broke the top of what seems like a 2" wire mesh filter in hard plastic cylindrical holder, that sits in the oil passage to this first crank main bearing, all the way to the bottom where the hole links to the turbo oil return hole on the side of block, and also to another hole where the chain tensioner sits.
The puzzle is this: what is the function of this filter inside the oil feed to only one of the main bearings?
Is it anything to do with turbo oil return and if so how the designer envisaged maintenance as to replace or clean it, you need to strip the engine to remove, clean, replace it?
Most importantly, where to find one now that I have damaged it?

Next puzzle is to do with bottom end stretch bolts. Fords, don't supply or sell them but the whole reconditioned bottom end at some £1500!
I have been told to use the old main bearing cap bolts! But as you can strech them no more, what torque to apply? This torque can not be the same as the one applied to new bolts with the 120 degrees! So danger of breaking off!
There is a chance that big end cap bolts can be found I ve been told, so waiting to see the guy in machine shop can get them!
The next puzzle is the depletion of engineering and manufacturing industry in GB that was once the envy of the world, but now a simple but fundamental component in engineering can't be found- damn you stretch bolts!

Can any one advise please?

[paul2012]

"oil gallery filter" See my rebuild thread here viewtopic.php?f=5&t=172985&start=30#p1474046

[Cellutron]

Yes, thanks. Managed to order one today! And the stretch bolts.