Jake "Torque" Davidson knew how to pull an engine without breaking a sweat, but he had never cooled one going eighty on dirt. That was the whole problem. Tinker wanted to learn, and Jake wanted to teach, but he couldn't teach a fix he hadn't proven. The copper cooling coils wrapped around Tinker's buggy engine looked right on the workbench. They had never run at racing speed. Until they did, Jake had nothing to pass on. The buggy sat low and sleek in the shed, hand-pump beside it, copper tubing snaking over the block. Jake crouched and traced the coils with one finger. "Flight engines don't get airflow down here," he said. "Full throttle on the ground, they cook. The coils should fix it. Should." Bam Bam Rubble stood in the doorway, the young caveman who had cleared this shed so Tinker had a place to work. He carried a split log under one arm out of habit. He set it down and looked at the pump. "You pump water. I push the buggy." He pointed to the dirt stretch outside. "We find out now." Jake stared at him. Simple. Dangerous. Right. "If the coils crack at speed, we lose the engine." "Then we know," Bam Bam said. "Guessing is worse." Jake made the call. He fired the engine. It caught rough, then smoothed. He grabbed the hand-pump and worked it. Water pushed through the copper. Bam Bam set both hands on the rear and shoved, and the buggy rolled hard across the dirt, throttle wide. The needle climbed. The engine screamed. Jake pumped faster, arms burning, eyes locked on the coils. A seam of copper bulged near the block. Heat shimmered off the metal. He kept pumping. The buggy hit racing speed, tires throwing grit, and the bulge held. The water ran hot but it ran. The coils did not crack. Bam Bam dug in and dragged the buggy to a stop. Jake killed the engine and pressed a bare hand near the coils. Warm, not scorching. He laughed, loud and surprised. "They hold," he said. "They actually hold." Then he saw it. Where the hot copper had flexed, it had rubbed against a bundle of engine wires. The insulation had melted through. Two bare wires touched, fused black at the tip. Jake's stomach dropped. A short circuit. The one thing he could never beat fast. The mouse-nest job had taken him three days to trace. Now he had a fix worth teaching Tinker, but the test that proved it had just chewed through the wiring. "Coils work," Bam Bam said, wiping his hands. "Coils work," Jake agreed. He stared at the melted wires. "But they melted the harness doing it." He stood slowly. Tinker was coming tomorrow to learn. Jake had a lesson to give now. First he had to find every wire the heat had touched.

The melted harness lay open on the bench. Jake traced each wire with a shaking finger. Twelve strands fed the engine, and the heat had cooked six of them black. One wrong splice and he could fry the whole block. Electrical gremlins had always beaten him. The mouse-nest job took three days. He did not have three days. Tinker came tomorrow to learn, and a bad guess would cost them the engine. Jake called his brother. Axel Wrench showed up an hour later, the mechanic who could rebuild an engine in twenty minutes and had once patched a fuel line with a boot lace. He leaned over the harness and said nothing for a while. Then he spoke plain. "You're guessing," Axel said. "Don't guess. Test." He pulled a small meter from his belt. "Power off. Touch both ends. The dead wires stay quiet. The live ones ring." Jake stared at the meter. "That's it? That finds the short?" "It finds the truth. Stop trusting your eyes." Axel set the meter in Jake's hand. He did not soften it. "You beat engines because you measure them. You lose on wiring because you stare and hope. Same job. Different tool." Jake killed the power. He touched the probes to the first pair of wires. The meter sat silent. Dead. He marked it with tape. He moved to the next pair. The meter buzzed. Live, and whole. He breathed out. For the first time the harness stopped feeling like a trap. It felt like a map. He worked down the bundle, pair by pair. Six dead wires, marked. Six live ones, clear. He cut the burned sections out. He stripped fresh copper, twisted each splice, and sealed them in heat-wrap away from the coil path. No guessing. Each one tested before he moved on. An hour passed. Jake connected the last splice and hit the meter a final time. Every strand rang clean. He fired the engine. It caught, smooth and steady. No smoke. No stall. The coils ran hot and the wires held. "It runs," Jake said. He laughed, loud. "I traced the whole thing in one night." Axel wiped his hands. "You didn't trace it. The meter did. You just believed it." He paused. "That's the part you keep forgetting." Jake looked at the clean harness. Tinker would arrive in the morning, and now Jake had the real lesson. Not the cooling fix alone. The method. Measure the wire. Trust the reading, not the eye. But he saw the problem too. He had routed the new splices tight against the block to keep them off the coils. Tomorrow Tinker would want to run the buggy at full speed. The fresh wires sat close to the hottest part of the engine. Jake frowned. He had beaten the short. He had just placed the next one an inch away.