Understanding the Situation
* 350 Turbo: This refers to the common General Motors automatic transmission used in a variety of vehicles from the 1970s to the 1990s.
* BM Shift Kit: BM stands for "Bowler Motorsports" or "B&M" (Bowler & Martin). These are popular brands for performance transmission upgrades.
Potential Causes
1. Incorrect Shift Kit Installation:
* Valve Body Issues: The shift kit's components need to be installed precisely within the transmission's valve body. Improper placement or incorrect adjustment of springs or check balls can severely affect shifting.
* Misaligned or Damaged Parts: Double-check that all components are in the correct position, haven't been bent or damaged during installation.
2. Other Transmission Problems:
* Fluid Issues: Low, dirty, or incompatible transmission fluid can hinder proper shifting.
* Clutch Packs: Worn or damaged clutch packs in the transmission can prevent third gear engagement.
* Governor Issues: The governor controls shift points and needs to function correctly.
3. Wiring and Electrical:
* Wiring Issues: Check for any damaged or loose wires connecting the transmission to the vehicle's electrical system, particularly those involved with the shift solenoids.
* Solenoid Problems: The solenoids control fluid flow within the valve body. Faulty solenoids can prevent the transmission from shifting into third gear.
4. Engine RPM Issues:
* Engine Stalling: If the engine stalls or loses power before reaching the point where third gear should engage, the transmission won't shift.
* Incorrect Governor Setup: The governor controls the RPM at which the transmission shifts. If the governor is misaligned or damaged, it could affect the shift points.
Troubleshooting Steps
1. Double-Check Shift Kit Installation:
* Refer to Instructions: Consult the specific instructions for your BM shift kit. It should have a detailed diagram showing component placement.
* Visual Inspection: Carefully inspect all components for damage, misalignment, and proper assembly.
2. Check Transmission Fluid:
* Level: Ensure the transmission fluid is at the correct level.
* Condition: Check the fluid for color and smell. It should be red and smell clean; if it's dark, burnt, or smells burnt, you need a fluid change.
3. Diagnose Electrical System:
* Wiring Checks: Look for damaged, loose, or corroded wires.
* Solenoid Testing: Use a multimeter or test light to verify the solenoids are receiving power and responding correctly.
4. Engine RPM Check:
* Engine Performance: Ensure the engine is running smoothly and is able to reach the RPM range where third gear should engage.
* Governor Function: Consider testing the governor's operation.
Seeking Expert Help
If you're not comfortable with the complexity of transmission repairs, it's best to consult a qualified transmission mechanic. They have the tools, expertise, and experience to:
* Properly diagnose the problem: They can use diagnostic equipment to analyze transmission performance and pinpoint the root cause.
* Carry out repairs: They have the skills to address any mechanical or electrical issues.
* Ensure correct installation of the shift kit: They can make sure the kit is installed correctly and components are adjusted for optimal performance.
Important Safety Note: Be aware that working on a transmission involves dealing with pressurized fluid and hot components. Exercise caution and use appropriate safety measures. If you're not comfortable working on your vehicle, leave it to a professional.
