Welcome to the continuation of a new DIY series where CorvSport canvasses the internet for the best do-it-yourself guides. Let CorvSport be your digital encyclopedia and bring you the best guides and resources from our vast Corvette community. This series can also give an enthusiast contemplating a DIY project the clarity needed to realize they should hire an expert.
Nearly every generation has at least one component that enthusiasts are urged to proactively replace due to some inherent issue. You’ll hear something like this: “If you don’t replace that now, it’s going to fail at the worst time and cause damage!” For instance, with the C5, that component is the harmonic balancer, and we’ve published a guide for that DIY fix here. For the fourth-generation Corvette, that component is the Opti-Spark. And today’s guide will also include a “while you’re in there” component, the water pump.
CorvSport Complexity Guide
- Difficulty: 7 (10 most difficult)
- Patience Needed: 9
- Level of Specialty Tools Required: 5
- Is a Helper Recommended? No
Today’s guide comes from Corvette Forum member “LT1*C4” and is the best and most comprehensive guide I could find on the internet. To augment this guide, I’ve also included a highly recommended YouTube video. This curated C4 Opti-Spark and water pump replacement is fully credited to “LT1*C4” and is being presented to our CorvSport community in an unedited format. You’ll note in these steps that LT1*C4 took the time to put the detailed instructions in the pictures.
How To Replace The Opti-Spark And Water Pump On Your C4
Step 1: Disconnect the battery
Step 2: Drain the engine coolant
Step 3: Unplug the IAT sensor
Step 4: Gain access to the throttle body and water pump
Step 5: Remove the coil wire
Step 6: Remove the passenger-side hose
Step 7: Unplug the IAC valve
Step 8: Remove the TPS sensor
Step 9: Remove the vacuum line
Step 10: Remove the coolant hoses
Step 11: Remove the throttle cable
Step 12: Remove the throttle body
Step 13: Preparation for water pump removal
Step 14: Disconnect the ECT sensor
Step 15: Remove the connection to the Opti-Spark
Step 16: Remove the serpentine belt
Step 17: Remove the water pump
Step 18: Remove the plug wires
Step 19: Remove the crank pulley
Step 20: You’re halfway done; time for some cleaning
Step 21: Check the weep hole on your water pump (if not replacing with a new one)
Step 22: Electric water pump installation preparation
Step 23: Opti-Spark preparation and installation
Step 24: Pulley reinstallation
Step 25: Opti-Spark preparation and installation
Step 26: Reinstall the plug wires
Step 27: Prepare and install the water pump
Step 28: Reinstall the 6 cover bolts
Step 29: Bypass the throttle body coolant (optional)
Step 30: Refill your coolant system
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