1. Identify the Source of the Leak:
This is the most crucial step. A clean engine is essential for this. Thoroughly clean the engine using engine degreaser and a pressure washer (carefully avoiding electrical components). Let it dry completely. Then, run the engine for a short time, then examine it closely. Look for:
* Valve Cover Gaskets: Oil leaking from the top of the engine, usually around the valve covers.
* Rear Main Seal: Oil leaking from the rear of the engine, near the crankshaft. This is often difficult to spot and can be messy.
* Front Main Seal: Oil leaking from the front of the engine, near the crankshaft. Similar difficulty to the rear main.
* Oil Pan Gasket: Oil leaking from the bottom of the engine, around the oil pan.
* Timing Cover Gasket: Oil leaking from the front of the engine, near the timing chain or belt.
* Distributor O-ring: If you have a distributor, a leak may appear around it.
* PCV Valve and Grommet: The Positive Crankcase Ventilation system can leak if the grommet is worn or the valve is damaged.
* Cracked Engine Block or Cylinder Head: This is the worst-case scenario and requires significant repair or replacement. Look for obvious cracks.
2. Gather Necessary Parts and Tools:
Once you've identified the leak, you'll need the appropriate parts:
* New Gaskets/Seals: Get the correct ones for your specific engine. Don't skimp on quality here; cheap gaskets can lead to recurring leaks.
* New RTV Silicone (if needed): Many gasket installations require a bead of RTV sealant for a proper seal. Use a high-temperature silicone designed for automotive applications.
* Tools: This will vary depending on the location of the leak, but you'll likely need sockets, wrenches, screwdrivers, possibly a torque wrench (essential for many gasket installations), and possibly specialized tools for seals (like a seal installer).
3. Perform the Repair:
This is where things get very specific. Repairing each type of leak requires different procedures:
* Valve Cover Gaskets: Relatively easy repair. Remove the valve covers, clean the mating surfaces, install new gaskets, and reinstall the valve covers, tightening bolts in a star pattern to ensure even pressure.
* Oil Pan Gasket: Requires dropping the oil pan. Clean the mating surfaces thoroughly, apply RTV sealant as needed, install the new gasket, and reinstall the oil pan.
* Front/Rear Main Seals: These are significantly more difficult and often require specialized tools and knowledge. It’s often best left to a professional mechanic.
* Other leaks: Each requires its own specific repair procedure. Consult a repair manual for your specific engine.
4. Reassemble and Test:
After the repair, reassemble everything, double-checking all connections and tightening bolts to the manufacturer's specifications (consult your repair manual). Refill the engine with the correct amount and type of oil. Run the engine for a short time, checking for leaks. Let it sit for a while, then check again.
Important Considerations:
* Repair Manual: A factory service manual for your specific year and model Chevy 350 is invaluable. It provides detailed instructions and torque specifications.
* Professional Help: If you're not comfortable working on engines, don't hesitate to take it to a qualified mechanic. Incorrect repairs can lead to more significant engine damage.
* Safety First: Always disconnect the battery's negative terminal before working on the engine. Use appropriate safety glasses and gloves.
This information provides a general overview. For specific instructions on repairing a particular oil leak on your Chevy 350, you'll need to consult a repair manual or seek professional help. The complexity varies greatly depending on the leak's source.
