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GMC 5.3L (325 cu in) firing order — diagram & guide

Achieving peak performance with the GMC 5.3L firing order.

The gmc logo with a man working on a car engine.
A man in a blue jacket smiling in front of a red wall.
Filip Gromovic November 7, 2023 |

Through the mid-2000s, the 5.3-liter engine proved to be one of the best-suited options for GMC SUV-class vehicles. It’s no wonder that it appeared in a wide range of different models, and these days most of these engines still run smoothly.

Of course, it’s completely normal to get some occasional misfires and worn-off spark plugs, so we’ve made this guide to help you out. We’ll be addressing the matter of the GMC 5.3L (325 cu in) firing order and cylinder numbering to give you some pointers on properly maintaining the engine.

GMC 5.3L firing order

The most important thing to note is that the GMC 5.3L firing order is 1-8-7-2-6-5-4-3 and it’s a standard firing order for Vortec engines made by GM. These engines were shared by a large number of GM’s subsidiary brands so GMC vehicles also get them under their hoods.

For this particular engine, the mentioned firing order is valid and it’s easy to apply it once you learn the cylinder positions. The engine is longitudinally placed which means it’s a regular V8 configuration, and we’ll discuss the cylinder numbers as well to ensure you’ll apply the firing sequence the right way.

GMC 5.3L cylinder arrangement

A white car with blue numbers on the hood.

We don’t need to stress the importance of knowing the cylinder positions twice, and if you are an experienced DIY mechanic you’ll know this. It’s the first step towards working on your engine, so we’ll try to explain it in the easiest way possible.

The 5.3-liter V8 engine has two cylinder banks – one on the left side of the engine and one on the right side. The left cylinder bank houses cylinders 2, 4, 6, and 8, while the right one has cylinders 1, 3, 5, and 7. Of course, this is front to rear when looking at the engine from a mechanic’s perspective outside of the car.

If you are sitting behind the wheel, the driver’s bank is that “right” cylinder bank with the first cylinder being closest to the front end near the radiator and the crank pulley.

GMC 5.3L vehicle applications

Finally, we have to give you a list of all the vehicles that use the 5.3-liter engine by GMC just to be sure that you’ll apply the right firing order. The list is pretty long considering all the models that used it overall since it’s not just GMC models, so here’s a complete overview:

As you can see, this engine was pretty common among GM’s brands and SUV or truck models including some less-known options like the Isuzu Ascender and the Saab 9-7X.

Our take

As you can see, the 5.3-liter V8 engine is pretty reliable in most vehicle applications and this guide will only serve you well in making it even more durable.

We hope you’ll be able to use the pieces of information listed in this guide for the benefit of your GMC SUV or truck since the 5.3L engine is said to last well over 250,000 miles with proper maintenance.

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