>>glowplug will shear off at 85-90NM

Very helpful data - thanks for posting them.

That agrees with my experience of these glow plugs. When I removed them, I steadily increased the torque wrench settings, and while most came out at about 50Nm, 2 of them needed a bit more. I was a bit worried about going beyond Beru's 45Nm figure, but I thought it likely that they were being cautious in their specification.

As I've mentioned a time or two, it's worth plugging the vacuum lines and starting the car with the inlet manifold off. That's how I found the failed inlet valve seats on my engine which otherwise would have remained dormant, but still sapping fuel and performance.