Who is affected?
Any and every BMW 318 with an M42 (16 valve twin-cam 4-cylinder) engine built prior to 11/93. This includes the E30 chassis sold as a 1991 model and 1992-1994 E36 chassis models.
What is the problem?
A rubberized gasket (officially known as the “Timing Case Profile Gasket”, often incorrectly referred to as the Head Gasket) measuring approximately 10 inches long and approximately 1.5 inches high that resides between the cylinder head and timing case is defective. I hesitate to put any exact statistics on it, but this gasket is failing at an EXTREMELY HIGH rate. I would guess a 95-97% failure rate. When it fails, coolant leaks from the engine into the engine compartment, usually near the vicinity of the passenger side of the steering rack/onto the AC compressor/onto the ground.
When does this occur?
*average* failure appears to be between 68,000 miles and 77,000 miles. Some of these gaskets gradually deteriorate, leaving telltale drops of coolant on garage floors, while there have been documented cases of others failing suddenly, leaving cars overheated, stalled, and slick coolant all over road surfaces. NOT good.
Why does this occur?
According to BMW Technical Service Bulletin Number 11 10 93 (3885) dated 11/93, the Timing Case Profile Gaskets fail due to inferior/defective rubber used in the manufacture of the actual gasket. Cars built after 10/93 have Timing Case Profile Gaskets made with “an optimized rubber material composition”.
How is the repair done?
Removal of the cylinder head is necessary for repair. This is very labor intensive, once the head is off, its simply a matter of scraping/removing the old gasket off, repairing any pitting of the metal surfaces using a JB Weld type compound, allowing ample time for the JB Weld to dry, then installing a new/improved gasket.