Engine repair options (BMW 7 Series E32)

A mechanic who intends to perform an engine overhaul will have to make a number of choices. The decision to replace the cylinder block, piston/connecting rod assemblies, and crankshaft depends on many factors, the most important of which is the condition of the engine block. Other factors include cost, availability of specialist workshops for machining, time required to perform the repair, and previous experience in performing similar work.

Some of the alternative repair methods are as follows.

Customized details

If the inspection has shown that the engine block and most of its components are in a condition that allows them to be used again, the most economical alternative is to purchase only the necessary parts and components. The cylinders, crankshaft and pistons/connecting rods should be examined very carefully. Even if there is only minimal wear on a cylinder, the cylinder bores should be ground.

Replacing the piston group

If the inspection shows that all parts are heavily worn, we recommend replacing the piston group with a new one, rather than buying parts separately. The piston group of the factory assembly includes sets of: pistons, rings (compression and oil scraper), piston pins, retaining rings.

Replace the connecting rods as a set. If necessary, if the connecting rods are not deformed or mechanically damaged, you can replace the piston pin bushings, but after replacement, you must ream the hole to the required diameter (fit the piston pin).

After a thorough inspection, the crankshaft must be replaced or reground to the next repair size.



Consider carefully which option is best suited to your circumstances and discuss the situation with specialists from the workshop or auto store, as well as with more experienced repairmen before ordering or purchasing replacement parts.

It is much easier to disassemble and work on an engine if it is mounted on a portable engine stand. Such a stand can be rented for a very reasonable fee. Before installing the engine on the stand, the flywheel/drive plate should be removed from the engine.

If you do not have a stand, you can disassemble the engine by securing it to the floor or table. Be extremely careful not to drop the engine when working on it without a stand.

If you intend to purchase a rebuilt engine, you will first need to remove all external components so that you can transfer them to the engine you purchase, just as you would if they were to be installed on an engine you decided to rebuild yourself.

Caution: When removing external components from the engine, pay close attention to all parts that may be useful during installation. Note the position of all gaskets, seals, bushings, studs, brackets, washers, bolts and other small parts.