Abstract: An improved hydrocracking process, in a process for conversion of components of a heavy hydrocarbon feed to lighter, more valuable products, wherein the feed comprises foulant, the process comprising: (a.) contacting the feed with hydrogen, in the presence of a hydrocracking catalyst, at an elevated temperature and pressure in a hydrocracker, to produce a hydrocracker effluent comprising foulant; (b.) cooling and depressurizing the hydrocracker effluent to form a cooled, depressurized hydrocracker effluent comprising foulant; (c.) separating the cooled, depressurized hydrocracker effluent into the products of the conversion and an unconverted portion of the hydrocracker effluent which comprises foulant; and (d.) recycling, as effluent recycle to the hydrocracker, the unconverted portion of the hydrocracker effluent to the hydrocracker, wherein the concentration of foulant in the hydrocracker effluent is increased; the improvement comprising: (i.