Cylinder heads with a machining flaw (hair line 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.