The 53 series is a wet sleeve engine. The 71 series is a dry sleeve. The most common coolant failure on the 71's is oring failure on the head gasket or a cracked cylinder head. You can also leak coolant from the injector tubes and the water pump seals. The oil cooler can leak also. Remove the valve cover and see if that engine still has the 2 valve head...........if so you will want to replace it with a 4 valve. OK, its not that necessary to update, but thats what I do when I run across them.
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