What you'll need:
* Clutch bleeding kit: This usually consists of a clear hose, a container to collect fluid, and possibly a one-man bleeder. A pressure bleeder is also an option and can make the process significantly easier and faster.
* New clutch fluid: Use DOT 3 or DOT 4 brake fluid, *never* DOT 5 silicone fluid (incompatible with other components). Have plenty on hand.
* Wrench: The size needed to fit the bleeder valve on the clutch slave cylinder. This is usually a 8mm, 10mm, or 11mm.
* Shop rags or paper towels: To clean up spills.
* Helper: Absolutely crucial for this job.
Procedure:
1. Locate the Bleeder Valve: This is on the clutch slave cylinder, typically bolted to the transmission bellhousing. It's often located near the bottom of the slave cylinder. Consult a repair manual for your specific truck model to be certain of its location.
2. Prepare the System: Have your helper sit in the truck with the engine OFF. Make sure the clutch fluid reservoir is full. Check the level regularly and top it off as needed during bleeding.
3. Attach the Bleeder Hose: Attach one end of the clear hose to the bleeder valve and the other end to the collection container. Make sure the hose is securely attached to prevent leaks.
4. Open the Bleeder Valve (Slightly): Your helper should gently pump the clutch pedal several times and then hold it down. While the pedal is held down, *slightly* open the bleeder valve to allow air bubbles to escape. You should see fluid flowing through the hose – if not, check for leaks.
5. Close the Bleeder Valve (Important!): *Before* your helper releases the clutch pedal, close the bleeder valve tightly. This prevents air from being drawn back into the system.
6. Repeat Steps 4 & 5: Repeat steps 4 & 5 several times until no more air bubbles are visible in the fluid coming from the bleeder valve. This may take several cycles of pumping and bleeding.
7. Check Fluid Level: Top off the clutch master cylinder reservoir frequently. Keep an eye on the fluid level throughout the process.
8. Test the Clutch: Once the bleeding is complete, have your helper test the clutch pedal for firmness and proper operation. The pedal should feel firm and not spongy. If it feels spongy, more bleeding is likely needed.
9. One-Man Bleeder (Optional): If you don't have a helper, a one-man bleeder kit can be used. These kits typically use pressure to force fluid through the system. Follow the instructions included with the kit.
10. Pressure Bleeder (Recommended): A pressure bleeder is the most efficient and reliable method. It applies consistent pressure to the master cylinder, ensuring a thorough bleed.
Important Considerations:
* Low Fluid Level: Never let the fluid reservoir run completely dry. This can introduce air into the system and damage the master cylinder.
* Repair Manual: A repair manual specific to your 1990 Chevy Cheyenne 4WD is highly recommended. It will provide detailed diagrams and instructions.
* Master Cylinder Replacement: If the clutch pedal remains spongy after repeated bleeding, the master cylinder might be faulty and require replacement. The same applies to a bad slave cylinder.
* Safety: Wear safety glasses to protect your eyes from splashing fluid. Brake fluid can damage paint and other surfaces, so clean up any spills immediately.
If you are not comfortable performing this task yourself, it's best to take your truck to a qualified mechanic. Bleeding a hydraulic clutch improperly can lead to clutch failure.
