1. Identify the Source:
* Is it definitely the belt? Spray a generous amount of silicone-based belt dressing (NOT WD-40; it's a temporary fix that can attract dirt and damage the belt) onto the belt while the engine is running. If the squeak stops temporarily, it's likely the belt. If not, the squeak might be coming from a pulley bearing or another component.
* Listen carefully. Try to pinpoint the location of the squeak. Is it consistent, or does it change with engine speed or load? This can help determine if it's the belt itself or a specific pulley.
2. Check Belt Tension and Condition:
* Visual Inspection: Look for cracks, glazing (shiny, smooth areas), fraying, or missing chunks of rubber on the belt. A worn belt needs replacing.
* Tension: Locate the belt tensioner. It's usually a pulley with a spring or hydraulic mechanism. There should be some give when you push on the belt between two pulleys. Consult your owner's manual or a repair manual for your Blazer's specific tension specifications. If it's too loose, the belt will slip and squeak. If it's too tight, it can put undue stress on the bearings and the belt itself. Adjusting tension usually involves turning a bolt on the tensioner. You might need a socket wrench and possibly a ratchet. Caution: The tensioner is under spring pressure, so be careful when adjusting it.
3. Clean the Belt and Pulleys:
* Cleaning: If the belt looks okay but is still squeaking, it might be glazed. Try cleaning the belt and pulleys with a degreaser and a clean rag or brush. Be sure to let everything dry completely before restarting the engine.
4. Consider Replacing Components:
* Replace the Belt: If the belt is cracked, glazed, or worn, replace it. This is the most common solution. Make sure you get a belt of the correct size and type for your 1999 Chevy Blazer. Your owner's manual or an auto parts store can help with this.
* Replace a Pulley: If you've determined a specific pulley is the source of the squeak (even after cleaning), that pulley likely needs to be replaced. A bad pulley bearing will continue to squeak even with a new belt.
5. Seek Professional Help:
If you're uncomfortable working on your vehicle, or if you've tried these steps and the squeak persists, it's best to take your Blazer to a qualified mechanic. A persistent squeak could indicate a more serious problem.
Important Safety Note: Always disconnect the negative battery terminal before working on any part of your vehicle's electrical system or drive belt system. Be aware of moving parts when the engine is running, and never put your hands or tools near a moving belt.
