Cylinder head — disassembly (BMW 3 Series E46)

Note: A new or reconditioned head can be purchased at service stations and from specialists. Since special tools and devices are required to disassemble and inspect the condition of the head and its components, and, in addition, repairs may require individual new parts that may not always be available, it may be more practical and cost-effective for a home mechanic to purchase a reconditioned head than to disassemble, inspect, and repair the old one. When disassembling a cylinder head, a device is required. For compressing the valve springs.

4-cylinder engines

1. Remove the cylinder head as described in chapter 2A.

2. Remove the intake and exhaust manifolds from the cylinder head (if this was not done before removing the head), rocker arms, pushers and hydraulic supports.

3. Using a valve spring compressor, compress each valve spring in turn and release the cotters. Release the spring and remove the retainer, spring and spring support washer. Note that on M43TU engines produced before September 1997, there are two springs on each valve. Using pliers, carefully remove the valve stem seals from the valve guides (fig. 6.3,a,b).





4. If the valve spring is compressed and the crackers do not want to leave their place, gently tap the device directly above the valve stem. The crackers should come free.



5. Remove the valve from the combustion chamber side.

6. It is important to store each valve together with its cotters, retainer, support washer and spring. In addition, these sets should be stored in a certain order, unless, of course, they are too worn and need to be replaced. If the valve sets are supposed to be reinstalled on the engine, store them each in their own plastic bag or box with a tag (Fig. 6.6). Keep in mind that the cylinder numbering starts from the side of the camshaft drive chain.

6-cylinder engines

7. Remove the cylinder head as shown in chapter 2B.

8. Remove the camshafts, tappets and camshaft bearings (chapter 2B).

9. Perform the actions specified in paragraphs 3-6, taking into account that the valves of 6-cylinder engines have one spring each.