DVA has provided some photographic proof of what has been known for a long time - Rover K series heads can suffer head gasket failure (HGF) due to poor casting and quality control in the Rover foundry. Poor control of hydrogen in the casting process, even after Rover installed a hydrogen scrub for the K series head castings, leads to small voids in the casting that can be big enough to breach the fire ring (as in the image).
Rover skimmed their heads in such a way as to collapse the immediate top layer of the material - the voids then being filled in or bridged, presenting a uniform face to the head casting. This enables the head gasket to seal correctly preventing failure. Of course this technique is less effective on edge areas like the fire ring.
Such heads are also going to be an issue when it comes to after market skimming. Removing the top "smeared" layer of material could easily expose voids. The use of shims could help.
So if you have a K Series head that requires skimming what should you do? Obviously carefully check after the skim that no porosity has been exposed but it would take use of ultrasound to spot any that are just under the surface and will collapse when the head is installed and used. Avoiding skimming in the first place is perhaps the best solution.
If you have a shagged head then avoid replacement with any K series head from 2000-2002 as these apparently these are the most porous. Other options include getting hold of a vulcan motorsport head but thats is likely to prove expense and hard to modify, or contact Nevlok in Coventry on 02476 450 777 - they sell sell K series castings.
£25.00
