Can I block of the engine oil cooler lines on a 1991 K1500 with 5.7l?

No, you should not block off the engine oil cooler lines on a 1991 K1500 with a 5.7L engine. The oil cooler is a critical component for preventing overheating, especially under heavy loads or in hot climates. Blocking them will cause the engine oil to overheat, leading to serious engine damage, including:

* Premature engine wear: Overheated oil loses its lubricating properties, leading to increased friction and faster wear on engine components.

* Seized engine: In extreme cases, the oil can become so thick it prevents proper lubrication, causing parts to seize and the engine to fail completely.

* Damaged oil pump: The increased viscosity of the hot oil can overload the oil pump.

While you might think it's a simple solution to a leak or a perceived problem, the risks far outweigh any perceived benefits. If you have a leak, find and repair the leak in the cooler lines or the cooler itself. If the cooler is malfunctioning, replace it. Blocking the lines is a dangerous shortcut that will likely cost you far more in the long run.