Fix Coolant Leaks: 1991 GMC C3500 Sierra SLX 7.4L V8 Standard Cab Pickup

Follow the steps in this video to see how to fix minor coolant (antifreeze) leaks in your 1991 GMC C3500. Leaking coolant / antifreeze is one of the more common types of leaking fluid from C3500 engines. Engine coolant (which is also called antifreeze or anti-freeze) moves through the inside of your C3500 engine and keeps it from overheating. Coolant / antifreeze can leak from the reservoir, radiator or any hose, in 1991 C3500 with the 7.4 liter engine. However, a coolant leak (aka an antifreeze leak) is most likely to occur where the hoses connect to the engine or radiator. Otherwise, your C3500 may have a radiator leak. This video shows you where the coolant reservoir, hoses and connections on your 1991 C3500 Sierra SLX are located and the steps needed to fix minor leaks.

A few things to note about coolant is that it is sweet tasting and highly toxic, so it can end up in the dog's stomach pretty quickly. If you ignore a small coolant leak long enough, you will run out of coolant, which leads to an overheated engine and other serious, but highly avoidable, problems. An anti-freeze leak can cause the temp sensor to record high engine temperatures in a 1991 GMC C3500. Always protect yourself with safety glasses and gloves when working with the coolant on your C3500.