However, if you're determined to tackle it yourself, here's a general overview. This is NOT a complete step-by-step guide and omits crucial details for brevity. You MUST consult a repair manual specific to your 1987 Chevy G20 van for detailed instructions, diagrams, and torque specifications.
General Steps (Highly Simplified):
1. Preparation: Disconnect the battery's negative terminal. Drain the coolant completely. Gather your tools: screwdrivers (Phillips and flathead), wrenches (metric), sockets, pliers, a coolant recovery system, new heater core, new O-rings, possibly new hoses, shop rags, and possibly a flush kit for the cooling system.
2. Dash Removal: This is the most labor-intensive part. You'll likely need to remove the steering column (partially or fully), glove box, radio, instrument cluster, possibly parts of the center console, and potentially the entire dashboard. This varies depending on the specific G20 model and trim level. Your repair manual will be crucial here. Take many pictures as you go!
3. Heater Core Access: Once the dash is out (or sufficiently disassembled), you'll locate the heater core housing behind the dashboard. This often involves removing various brackets and components to gain access.
4. Heater Core Removal: Carefully disconnect the heater hoses from the core. Expect coolant leakage. Be prepared to catch the fluid. Then, remove the heater core itself. This may involve removing screws, clips, or other fasteners. The core is usually a relatively fragile component.
5. Installation: Install the new heater core, ensuring the O-rings are properly seated. Reconnect the hoses. Double-check all connections for leaks.
6. Reassembly: Carefully reassemble the dashboard and all the components you removed in reverse order of disassembly. This is just as painstaking as the disassembly process.
7. Coolant Refill and System Pressure Test: Once everything is back together, refill the cooling system with coolant, following the proper procedure for your vehicle. Perform a pressure test to check for leaks.
8. Final Check: Run the engine and check for leaks, proper heater operation, and for any unusual noises.
Important Considerations:
* Repair Manual: A factory service manual or a Haynes/Chilton manual specific to your 1987 Chevy G20 is absolutely essential. These manuals provide detailed diagrams and instructions that are crucial for success.
* Coolant Type: Use the correct type and concentration of coolant for your system.
* Bleeding the System: After refilling, you'll likely need to bleed the cooling system to remove any trapped air bubbles.
* Patience: This is a long and challenging job. Be patient and methodical.
* Safety: Wear safety glasses and gloves. Coolant is corrosive.
Again, strongly consider seeking professional help from a qualified mechanic. The cost of professional repair might be less stressful and potentially less expensive than the time, effort, and potential damage involved in a DIY attempt. The labor cost alone can be substantial, though, reflecting the difficulty of the job.
