Is changing the anti-freeze required when intake manifold on a 1996 Chevy Tahoe 5.7 liter engine?

While not strictly *required*, draining some or all of the coolant is highly recommended when removing the intake manifold on a 1996 Chevy Tahoe 5.7L engine. The reason is that the intake manifold often sits very close to or even over coolant passages, and there's a significant risk of coolant spilling or contaminating the engine during the removal process.

Therefore, while you might *technically* get away without a full coolant change, it's far safer and more prudent to drain a significant portion, if not all, of the coolant before starting the job. This minimizes the risk of contamination and makes the job cleaner and easier. Once the manifold is reinstalled, refilling with fresh coolant is a good practice anyway, as it ensures a clean system.