1. Locate the Leak:
* Clean the engine thoroughly: Use a degreaser and engine cleaner (following directions carefully), then rinse with water and allow to dry completely. This is crucial for accurately identifying the source.
* Inspect carefully: Once dry, run the engine briefly (be mindful of safety!), then carefully examine the engine bay. Look for fresh oil stains or drips. Pay close attention to these areas:
* Valve cover gasket: A common source of leaks. Look for oil around the top of the engine.
* Oil pan gasket: Located at the bottom of the engine. Look for oil pooling under the engine.
* Rear main seal: This seal is notoriously difficult to replace and is located where the crankshaft enters the transmission. Leaking here will show oil dripping down the back of the engine.
* Oil filter: Check the gasket and the filter itself for leaks.
* Timing cover gasket (if applicable): Less common, but possible.
* Crankshaft seals (front and rear): These seals prevent oil from escaping the engine.
* Other seals and gaskets: Various smaller seals and gaskets can leak.
2. Identify the Severity:
* Minor leak (weep): A small amount of oil seepage might only require replacing a gasket or tightening bolts.
* Moderate leak: Consistent dripping requires more significant repair, likely involving gasket replacement.
* Major leak: Significant oil loss might indicate a more serious problem requiring professional attention. Driving with a major leak can cause catastrophic engine damage.
3. Repair Options (depending on the source):
* Valve cover gasket replacement: This is often a DIY-friendly repair. It involves removing the valve cover, cleaning the mating surfaces, and installing a new gasket. Requires basic tools and mechanical aptitude. You'll find numerous online tutorials for this specific repair on your Blazer.
* Oil pan gasket replacement: Also relatively accessible for DIYers, but more involved than the valve cover gasket. Requires draining the oil, removing the oil pan, cleaning surfaces, and installing a new gasket.
* Rear main seal replacement: This is a significantly more complex repair, generally requiring specialized tools and experience. It is often best left to a professional mechanic.
* Oil filter: Simply replace the oil filter with a new one, ensuring the gasket is properly seated.
* Other seals and gaskets: Repair depends on the specific location and accessibility. Some may be relatively easy to replace; others might necessitate professional help.
4. Tools and Materials:
You'll need basic tools (sockets, wrenches, screwdrivers), a new gasket (the correct type for your specific leak location), oil, and potentially a new oil filter. Consult a repair manual or online resources specific to your 1999 Chevy Blazer's engine (e.g., 4.3L Vortec V6, etc.) for detailed instructions and torque specifications.
5. Professional Help:
If you're not comfortable with automotive repair, or if the leak is significant or in a difficult-to-access location (like the rear main seal), it's crucial to take your Blazer to a qualified mechanic. Ignoring an oil leak can lead to serious engine damage.
Disclaimer: This information is for general guidance only. Improper repair can result in further damage. Always consult a repair manual specific to your vehicle and use caution when working on your vehicle. If you are unsure about any step, seek professional help.
