Here's a breakdown of likely culprits and why you need a professional:
* Transmission Problems: This is the most probable cause. Internal issues within the automatic transmission, such as worn clutches, a malfunctioning valve body, or a damaged planetary gearset specifically affecting forward gears, could be the root of the problem.
* Torque Converter Issues: The torque converter connects the engine to the transmission. A problem within the torque converter could prevent power from being transmitted to the forward gears.
* Shift Linkage/Selector: While less likely given it works in reverse, a problem with the shift linkage or the selector itself *could* be preventing the transmission from engaging forward gears correctly.
* Engine Issues (Less Likely): While less probable given reverse works, a severe problem with the engine's power delivery (like a major internal failure) *could* manifest as a loss of forward motion while still allowing reverse.
* Electrical Problems: Faulty sensors, wiring harnesses, or the transmission control module (TCM) could disrupt the signal to engage forward gears.
What you should do:
1. Do NOT attempt to drive the car further. Continuing to drive it could cause further damage to the transmission.
2. Have it towed to a reputable mechanic: Ideally, find a specialist who is experienced with older BMWs and automatic transmissions. A regular mechanic might not have the specific knowledge or tools to properly diagnose this type of problem.
3. Describe the problem clearly: Tell the mechanic exactly what's happening – that the car goes into reverse but not forward – and mention the year and model of your BMW.
4. Get a proper diagnosis: Don't authorize any repairs until you understand the problem and the cost of the repair. A good mechanic will provide a clear diagnosis before starting any work.
Ignoring this problem will almost certainly lead to more expensive repairs down the road. Get professional help immediately.
