I had a similar thing with my 12j not reaching temperature in yhis cold weather.
I removed the shroud and fan but still it ran cold. Fitted rad blind but that made no difference either.
Replaced the thermostat, refitted the fan and shroud and now the temp gets to half on the guage within a couple of miles and the heater works!
As for repairing the shroud, as above, drill the ends of the cracks to stop them spreading then drill holes either side of the cracks and stitch it together with cable ties.
I imagine it would be fine without it though
So the temp gauge is meant to be at 1/2 way? I always assumed that 1/4 way was fine, had no idea that counted as cold running, would any adverse effects occur if it was routinely run with the temp gauge 1/4 way? In reference to the shroud most of the cracks surround the retaining bolts and can't really be repaired.
