1. Diagnosis (Crucial First Step):
* Isolate the Noise: Try to pinpoint the source of the noise. Is it definitely the input shaft bearing? The noise from a bad input shaft bearing is often a whine or growl that changes pitch with engine speed. It might be confused with other noises (wheel bearings, transmission issues, etc.). Jacking up the car and running the engine in neutral (carefully!) might help isolate the source.
* Check the Transmission Fluid: Is the fluid low? Is it dirty or discolored (metallic sheen)? Low or contaminated fluid can exacerbate bearing wear.
* Professional Inspection (Recommended): Unless you're a highly experienced mechanic with transmission repair experience, it's best to take your car to a qualified mechanic specializing in Mitsubishi Evo's or performance vehicles. They have the tools and expertise to properly diagnose the problem. A misdiagnosis can lead to unnecessary and expensive repairs.
2. Possible Solutions (after proper diagnosis):
* Bearing Replacement: If it's indeed a bad input shaft bearing, replacement is the only real solution. This is a major repair requiring transmission removal, disassembly, and reassembly. It's not a DIY job for beginners.
* Transmission Overhaul (Potential): Since the transmission needs to be opened, a thorough inspection of the rest of the transmission components is recommended. Other parts may be worn or damaged and replacing them proactively is often cost-effective compared to another repair down the road. This might include synchros, seals, and other bearings.
* Transmission Replacement (Worst Case): In severe cases, the transmission might be beyond repair. A replacement transmission (either used or new) might be necessary.
3. Costs:
Expect significant repair costs. Replacing just the input shaft bearing will be expensive due to the labor involved. A full transmission rebuild will be significantly more costly. Used transmissions can offer a more affordable alternative, but their condition needs careful assessment.
4. Prevention:
* Regular Maintenance: Regular fluid changes (using the correct transmission fluid specified for your Evo VI) are crucial to prolong the life of the transmission and its components.
* Avoid Harsh Driving: Aggressive driving, especially frequent hard launches, puts significant stress on the transmission.
In short: Don't ignore a noisy input shaft bearing. Get it diagnosed by a qualified mechanic ASAP to prevent more extensive and costly damage. The cost of repair will depend heavily on the extent of the damage.
