Much has been written about the failure of K Series head gaskets and the reliability of the engines.
What happens:
Overheating of the K Series is the main cause of the problem. This overheating causes movement of the cylinder head which leads to failure of the gasket. The overheating is often caused by a loss of coolant or failure of the pressure cap.
The K Series engine uses a sandwich design with the cylinder head retained by long bolts that go through the block and fix into a lower rail, clamping the engine together. The original design also allowed for expansion movement in the cylinder head. To achieve this, the cylinder liners sit slightly proud of the block and a gas tight seal is produced around the combustion chamber.
The expansion movement is between the head and block castings around the water jacket & oil ways. The original composite gasket features silicone beading to allow for this expansion whilst maintaining a seal. When the engine overheats, the cylinder head moves outside of the original design tolerances and the beading fails - causing failure.
The cylinder head is also located using dowels. The original dowels were made from nylon and are not strong enough to prevent movement of the cylinder head, leading to gasket failure.
The cure:
The gasket failure problems of the K Series can be overcome by using the Multi Layer Steel (MLS) type of head gasket and the uprated lower rail.
This gasket set is a two part kit. The main part is a 3 layer MLS gasket; the second part is a special Head Saver shim. The 3 layer gasket works as per a normal head gasket with fire rings around the combustion chambers and sealing oil and water ways.
The Head Saver shim is a special gasket that should be used if the head has to be skimmed. The shim is treated on the upper face with a special bonding compound that binds to the cylinder head as the engine heats up. This MLS gasket set is supplied with steel dowels for positive head to block location.
The uprated lower rail is stronger than the original Rover item. The additional strength of this lower rail and the steel dowels keep the cylinder head firmly fixed to the block, and combined with the multi layer cylinder head gasket, eliminate the head gasket problems.
We recommend that new cylinder head ‘stretch’ bolts be used and any work carried out to your engine is done in accordance with a factory workshop manual. Whilst you are doing this job we consider it advisable to replace the water pump and expansion cap to minimise any future problems. Please refer to the service parts section for more information.
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