Home › Forum › Ask A Member › 1958 Lark 35 › Re: 1958 Lark 35
There is a hole drilled at an angle between the pump outlet area and the drive shaft area. Make sure that hole is open. Make sure there are no holes in the copper "down" pipe. Some have a hole in the "up" pipe. That is OK. A mistake many people make is removing the thermostat housing and relief valve, already mentioned. That allows air into the return line to the pump. Rare, but it happens is a crack behind the long narrow plate on the side of the gearcase. If it has ran hot, the head gasket and/or exhaust cover gaskets may be leaking, allowing air into the cooling system. In short, anything that allows air into the cooling system to return to the pump may be the problem.