When a 4AGE Breaks – The Beginning
When a 4AGE breaks, it doesn’t go down quietly. My mechanic learned this the hard way. He had a Toyota Corolla SEG AE100 fitted with a 4AGE 20V silver top engine as track car. At first, the car only had a minor issue — it was losing coolant. But instead of fixing it, he kept pushing the engine to its limits. He believed in the toughness of Toyota’s engineering.
Week after week, he topped up coolant and kept driving hard. One day, he called me. The engine had started knocking. Moments later, it stalled completely. It wouldn’t even crank. A compression test confirmed the worst — all four pistons had zero pressure. The 4AGE was dead.
Diagnosing the 4AGE Engine Knock
When a 4AGE breaks, the first thing you do is check the ignition and ECU. Ignition was fine. But when he opened the ECU, things got ugly. Several capacitors and diodes were burnt. The damaged ECU could’ve triggered the engine knock.
He repaired the board and even tested a replacement ECU. Still, the engine wouldn’t turn over. So, he took the next step — disassembling the engine.
Good News: The 4AGE Was Still Salvageable
Surprisingly, the internals weren’t destroyed. There were no bent valves or damaged pistons. Instead, a worn head gasket caused the loss of compression and coolant leak. A small issue turned big due to neglect.
He replaced the gasket with a new one. Since the top part was already removed, he decided to clean and polish the cylinder head. A basic gasket job turned into a top overhaul.
Adding Style While Fixing What Broke
When a 4AGE breaks and you have to pull it apart, it’s a perfect excuse to beautify things. Inspired by our past engine bay upgrades, he decided to paint the engine cover and manifold. We brainstormed a few styles. He picked the most detailed design.
After some sanding, priming, and careful spraying, the 4AGE 20V looked brand new. It wasn’t just running again — it looked fantastic.
When a 4AGE Breaks – Lessons Learned
The moral here? Don’t ignore coolant loss. A simple issue, if left unchecked, can cause major failures. But thankfully, Toyota’s 4AGE is a tough little engine. Even after overheating and ECU damage, it came back strong — with a fresh look, too.
Thinking of giving your 4AGE a second life? Whether it’s a full rebuild or a custom paint job, feel free to reach out or drop a comment!
