Hello there
I have recently replaced the HG on my 1.6TD to a AAZ metal one. and also switch to ARP studs.
there are a few questions I need answered.
1. The shop I got the job done from, when tightening the studs, DID NOT use the OEM tightening pattern, as per the Bentley Manual. And I think that has caused the HG to leak. Are my suspicions plausible or am i just thinking too much?

WHY AM I THINKING THE HG IS LEAKING/BLOWN.
a. When the engine reaches normal temperature, the hoses are fairly hard. if i press them, they're not as hard as wood, but say 70% hard. you can still press but they aren't completely soft. Is that signalling a blown/leaking HG???
b. there is oil leaking from the top left corner (next to timing belt, on the manifold side) of the engine. I know for a fact that the inlet manifold gasket and BOV o-ring are leaking, and my turbo is spitting oil too, BUT I think the HG is leaking from that corner as well.
2. The ARP studs, I got in 2010, and I bought the items specified for Ford Sierra, part # 251-4701.
The instructions sheet that came along said tighten them to 90Nm. but I got them tightened to 90 lb-ft (with the wrong tightening sequence) and then tightened them to 100 lb-ft , (the last 10lb-ft using the correct tightening pattern).
I need expert opinion on this.
Rest is all good.
Doing a dynamat sound deadening project on the interior these days.
Cheers