BMW M70 / M73 / M73TU Family
Table of Contents
All Engines
Problems
- Distributor caps and rotor arms should be checked at 80k miles – if they’re worn, the engine will be down on power and get poor fuel economy
- Rubber couplers between the intake manifolds and heads can spring vacuum leaks and it’s a big job to replace them
- Oil spray bar banjo bolts can slacken and cause problems
- Throttle stepper motors can cause EML faults
- Oil can leak from the upper timing cover
M70
This engine is, in essence, two M20B25 six-cylinder engines slapped together (albeit with some differences). It has two distributors, two throttle bodies, two fuel pumps, two fuel rails, two MAF sensors, two crank position sensors, two coolant temperature sensors, and two engine computers. This makes troubleshooting issues a challenge, as it predates OBD2.