Here's a general outline of the process, but it will *vary* depending on the specific engine and whether you have power steering, air conditioning, and other accessories that impact the serpentine belt routing:
1. Safety First:
* Disconnect the negative battery terminal. This prevents accidental shorts and electrical damage.
* Engage the parking brake.
* Wear safety glasses and gloves.
2. Gather Tools and Materials:
* Repair Manual (essential): A Haynes or Chilton manual for your specific year and engine is crucial.
* Socket set and wrenches: Various sizes will be needed, depending on the bolts holding the tensioner.
* Ratchet and extensions: To reach those hard-to-access bolts.
* Wrench (or socket) for the serpentine belt: Some tensioners have a specific tool for this, but a long wrench or a large socket might work.
* New belt tensioner: Ensure you get the correct replacement part for your van.
* New serpentine belt (recommended): Since you're already in there, replacing the belt is a good preventative measure. The old belt might be damaged from the failing tensioner.
* Jack and jack stands (optional but recommended): For easier access to the underside of the van.
3. Accessing the Belt Tensioner:
* Locate the belt tensioner: This is usually a pulley with a pivoting arm. Your repair manual will show its exact location.
* Identify the tensioner bolt(s): These bolts secure the tensioner to the engine block or other component.
4. Releasing Tension:
* This is the most critical step and varies widely depending on the tensioner design: Some tensioners use a long bolt that you turn to release tension. Others may have a pivoting arm that requires a wrench or a special tensioner tool. Your repair manual will be essential here. Incorrectly releasing tension can result in the belt snapping back and causing injury.
* Once tension is released, the belt should be easily removable.
5. Removing the Old Tensioner:
* Remove the bolts securing the tensioner.
* Carefully remove the old tensioner. There might be other components (e.g., an idler pulley) connected to the tensioner.
6. Installing the New Tensioner:
* Install the new tensioner, ensuring it's properly aligned.
* Secure it with the bolts. Tighten them to the torque specification in your repair manual.
7. Installing the Serpentine Belt:
* Route the new serpentine belt (or the old one if it's still good) according to the routing diagram in your repair manual. This is extremely important – incorrect routing can damage the belt and engine components.
* Make sure the belt is properly seated on all pulleys.
8. Testing and Reassembly:
* Reconnect the negative battery terminal.
* Start the engine and check for any unusual noises or belt slippage.
* Check the tensioner operation. It should freely pivot when the engine is running.
* If everything is working correctly, you're done.
Important Considerations:
* Torque Specifications: Always tighten bolts to the manufacturer's specified torque. Using a torque wrench is vital to prevent damage.
* Diagram: Use a diagram from your repair manual to ensure correct belt routing.
* Professional Help: If you're uncomfortable with any part of this process, take your van to a qualified mechanic. This is not a trivial repair.
This is a general guide; consult your repair manual for specific instructions and diagrams tailored to your 1990 Chevy van's engine. Improper repair can cause serious damage. Safety first!
