A top gasket set contains only the sealing items required to service the upper section of the engine block, such as the head gasket, intake manifold rings, and rocker cover seals. A full overhaul kit includes every single internal and external seal for the entire engine, covering bottom-end oil pan seals, front and rear crankshaft seals, and timing cover profiles.

High-output turbo-charged diesel engines develop incredible peak cylinder pressures during rapid load transfers. Multi-layer steel gaskets offer superior spring-back characteristics and mechanical strength compared to old composite fibers, meaning they can flex with structural shifts without blowing out under pressure.

If the rocker cover gasket is made from high-grade silicone or rubber and remains completely pliable without physical tears or hardening, it can sometimes be carefully re-fitted. However, if the seal has baked hard from engine heat or is made from compressible cork, it must be replaced to prevent stubborn oil weeping along the top deck.