Cylinder heads with a machining flaw (hairline crack) may have been installed on M52TU engines in production on a limited number of vehicles. The machining flaw (if present) is located in the front right side of the cylinder head and will cause a coolant leak in the area of cylinder 1 as shown in the illustration (Figure 1).
Only if a customer complaint is received and a coolant leak is verified coming from the area shown in the illustration, should the cylinder head be replaced, according to BMW.
Replace the cylinder head and replace all valve stem seals as outlined in the appropriate repair manual (repair group 11 sections U 12 100 and 11 12 503).
Some or all of this information was provided by the Automotive Parts Remanufacturers Association (APRA). For more information on technical bulletins available through APRA call 703-968-2772 or visit www.AutoBulletins.com.