Coolant Leak in a Chevrolet 4.3

by Justin Cupler

The 4.3-liter V-6 engine is used in several Chevrolet vehicles through the 1990s and early 2000s, such as the S10, Silverado, C-Series and Astro Van. When a coolant leak surfaces, it is important to know how to test it and where to look for the leak.


The testing process involves pouring a small amount of dye into the cooling system and pressurizing the cooling system. The user then searches for the dye using an ultraviolet light and UV-sensitive glasses.


The first place to check for a coolant leak is the radiator. The 4.3-liter's radiator has plastic tanks on either side connected to an aluminum core. Focus on the seal between the tanks and the core, and look for cracks in the plastic tanks.

Water Pump

The water pump is located at the front of the 4.3-liter, directly behind the fan. This component can either leak from the seal between it and the engine or the small hole on the fan side of the pump. The latter is called a weep hole, and coolant will only leak from this as an indicator that the water pump bearing has failed.

Head Gaskets

The 4.3-liter V-6 has two cylinder heads, one on each side of the engine below the valve cover. Check where the engine and the cylinder heads meet for a leak in the seal.

About the Author

Justin Cupler is a professional writer who has been published on several websites including CarsDirect and Cupler has worked in the professional automotive repair field as a technician and a manager since 2000. He has a certificate in broadcast journalism from the Connecticut School of Broadcasting. Cupler is currently studying mechanical engineering at Saint Petersburg College.