A Crack in my block?
Perhaps you have been told you have a crack in your engine block and wondered what that meant exactly and obviously your mechanic wasn’t referring to Danny here working under your hood. A crack in your block could mean exactly what he has stated but with the Rover V8, this crack is internal to your engine relative to a coolant passage.
Your engine cylinders are surrounded by a water which is where your antifreeze circulates to carry the heat away from the cylinders. The water jackets are separated within the aluminum structure whereas they never come in contact with the moving parts like your pistons, spark plugs, crank and so forth.
When these engines were first casted (manufactured), the process allowed certain levels of porosity/voids to form in the block. These micro pockets of air or fractures can be of various size and shape throughout the structure making the water jackets a very sensitive area with the Rover V8 blocks. When aluminum heats up, it heats and expands at a different rate than the other metals in the engine. When it cools, it cools or contracts at a different rate as well. These events over time can create eventual passages for which the water (antifreeze) can move from the water jacket portion of the engine to other internal chambers.
The path of the water is from the water jacket through the cylinder wall which is where the cylinder liners are located. The picture below is a cross section cut of the block through 2 of the cylinders and liners removed. The water jackets are the long narrow passages which surround the cylinder bore.
The next image is what is left of the factory liner once removed from a cylinder bore. The darkest coloring on the liner is where coolant has found its way through the water jacket and come in contact with the liner. From there, the coolant was able to travel around and eventually up into the combustion chamber. Once this has occurred, your engine management system will detect a continual misfire as the plug becomes wet with antifreeze and cannot fire and the engine is now “consuming” coolant.