Poor Fuel Economy A leak in the exhaust manifold can reduce your vehicle's fuel efficiency. 21 déc. 2021 · What Are Exhaust Manifold Gasket Leak Symptoms? If you hear a clicking or ticking noise under the hood when starting your car or truck, that usually disappears after the engine warms up, it could mean there’s an exhaust manifold leak due to a cracked or broken exhaust manifold or broken exhaust manifold gasket.