GM Cadillac 1967-1989 Repair Guide



All Cadillac engines covered in this guide whether V6 or V8 are water-cooled power plants with pushrod valve actuation. All engines use cast iron cylinder heads and blocks, except the 8-250 and 8-273 V8's which use an iron/aluminum alloy block.

The gasoline V8's are all very similar in construction and share common design features such as chain-driven camshafts, hydraulic valve lifters and pressed-steel rocker arms. The 8-429 and 6-252 engines differ in that they have their rockers mounted on shafts. Because of this similarity between the engines, many removal and installation procedures given here will cover several engines simultaneously.

The 8-350 diesel engine is derived from the 8-350 Oldsmobile gasoline engine, except that the cylinder block, crankshaft and main bearings, connecting rods and wrist pins are heavier duty in the diesel engine (due to the much higher compression ratio). The diesel cylinder heads, intake manifold, ignition and fuel systems also are different from their gasoline engine counterparts. Also, Aircraft-type hydraulic roller valve lifters are used in the diesel engine.

The 8-368 engine has two major variations, the conventional design V8 and the (MD) Modulated Displacement engine known as the V8-6-4. The number of cylinders operating varies according to throttle position and load. Reducing the number of cylinders operating is accomplished through the use of valve selectors. At low power levels, valve selectors deactivate both intake and exhaust valves on two or four cylinders; for full power output, normal valve operation is restored.

The 8-250 and the 8-273 V8 engines are the only engines in the Cadillac line that use an iron/aluminum alloy block. It is imperative that torque specifications be followed for all the fasteners on this engine to prevent the threads from being stripped. The cast aluminum pistons are fit into cast iron cylinder liners which themselves are fit into the iron/aluminum alloy block.