1. Preparation:
* Safety First: Jack up the Blazer securely using jack stands. Never work under a vehicle supported only by a jack. Wear safety glasses.
* Gather Supplies: You'll need:
* New differential fluid (check your owner's manual for the correct type and weight – usually 75W-90 or 75W-140, possibly synthetic).
* A new crush washer for the fill plug (essential to prevent leaks).
* A drain pan to catch the old fluid.
* A wrench or socket that fits the drain and fill plugs.
* A funnel (preferably a flexible one).
* Rags or paper towels.
2. Draining the Old Fluid:
* Locate the Drain Plug: This is usually located at the bottom of the differential housing on the rear axle.
* Remove the Drain Plug: Carefully loosen and remove the drain plug, letting the old fluid drain completely into your drain pan. Be careful; the fluid will be hot if the vehicle has been recently driven.
* Inspect the Old Fluid: Check the color and consistency. Metallic particles or a burnt smell indicate potential problems.
3. Replacing the Drain Plug:
* Clean the Drain Plug: Wipe the drain plug clean.
* Install the Drain Plug: Replace the drain plug and tighten it securely (don't overtighten).
4. Locating the Fill Plug:
* Find the Fill Plug: The fill plug is usually located on the top or side of the differential housing. It might be slightly higher than the drain plug. This is often a different size than the drain plug.
5. Filling the Differential:
* Remove the Fill Plug: Remove the fill plug.
* Add New Fluid: Using the funnel, slowly add the new differential fluid. Refer to your owner's manual for the correct amount. You'll know you've added enough when fluid begins to trickle out of the fill hole.
* Replace the Fill Plug: Install the new crush washer onto the fill plug before screwing it back into the differential housing. Tighten it securely.
6. Clean Up and Lower the Vehicle:
* Dispose of the old fluid properly. Check with your local regulations for proper disposal methods.
* Carefully lower the Blazer using the jack stands.
* Check for leaks around both plugs.
Important Notes:
* Overfilling can damage the differential. It's better to slightly underfill than overfill.
* If you're unsure about any step, consult a qualified mechanic. This is a relatively straightforward task, but incorrect procedure can cause damage.
* The location of the drain and fill plugs can vary slightly between Blazer models. Always refer to your owner's manual or a repair manual specific to your vehicle.
Remember safety first! Always use jack stands and follow proper safety procedures when working under a vehicle.
