Abstract: A hung combustion chamber for internal combustion engines comprising a cylinder and detachable cooling jacket welded to a cylinder head. The cylinder and the cooling jacket are within a cylinder block, but unsupported by the cylinder block. Coolant is supplied to the jacket by a non-rigid connection. The hung combustion chamber contains the combustion gas pressures and temperatures while the jacket contains the coolant flows, eliminating many gaskets, seals, attachment and alignment components. The simplified one-piece chamber construction and limited number of components reduce stress concentration points and hot spots. The hung combustion chamber is particularly applicable to the retrofitting of existing worn diesel engines in heavy duty service environments.