* Clutch not fully disengaging: This is the most likely culprit. Even with a new clutch, improper adjustment of the clutch cable (if cable-operated) or hydraulic system (if hydraulic) can prevent the clutch from fully separating the engine from the transmission. The pressure plate might not be releasing fully, leaving the clutch disc slightly engaged, preventing gear selection.
* Clutch cable (if applicable) adjustment: If your Geo Storm has a cable-operated clutch, the cable might be too tight. This needs adjustment. Too loose is less of a problem than too tight.
* Hydraulic system issues (if applicable): If your Geo Storm has a hydraulic clutch, there might be air in the hydraulic line, a leak in the system, a failing slave cylinder, or a failing master cylinder. This prevents the proper release of the clutch. Bleeding the clutch system is essential here.
* Transmission problems: While less likely immediately after a clutch replacement, there's a small chance of a transmission problem. This could include:
* Worn synchronizers: Synchronizers help match the speeds of the gears before engagement. Worn synchronizers make shifting difficult, especially into certain gears. This is more likely to manifest as difficulty shifting into gear, but not impossible to be only evident when the engine is running.
* Bent shift fork: This is a rare possibility, but a damaged shift fork could prevent a gear from engaging properly.
* Internal transmission damage: This is less likely after a recent clutch replacement, but serious internal damage could prevent gear selection.
* Incorrect clutch installation: While unlikely if done by a mechanic, a wrongly installed clutch could also cause this. The alignment of the clutch disc and pressure plate is critical.
Troubleshooting Steps:
1. Check the clutch cable (if applicable): Adjust the clutch cable according to your car's specifications. Too tight is the most likely problem here.
2. Check the hydraulic system (if applicable): Look for leaks. If you have any experience with bleeding brakes, bleeding the clutch system (master cylinder to slave cylinder) is the next step. If you're not comfortable doing this, have a mechanic do it.
3. Listen for unusual noises: While trying to shift, listen carefully for any grinding, whining, or other unusual noises from the transmission. This can help pinpoint the source of the problem.
4. Try shifting with the engine off: If you can shift gears easily with the engine off, the problem is almost certainly with the clutch not fully disengaging.
5. Try shifting with the engine running, but clutch pedal fully depressed: If you can still not shift gears, that points more towards an internal transmission issue.
If you've tried these steps and are still unable to shift gears, it's best to take your Geo Storm to a mechanic specializing in manual transmissions for a proper diagnosis. They have the tools and experience to identify the specific problem and perform the necessary repairs.
