Of all the components that silently toil away in the Duramax engine bay, one of the things that gets most overlooked by drivers is the humble motor mount. Yes, this simple part may not seem that important to the uninitiated, but it forms a crucial link between the engine and the body of your truck. For most people, the stock rubber mounts that are utilized by General Motors in 2001 to 2010

Duramax engines do the job well enough but for those that put their truck through the wringer with hardcore towing or have that deep need to push the horsepower limits; those stock rubber motor mounts are quickly overwhelmed and will succumb to a destructive phenomenon known as driveline lash.

So, what can owners of 2001 - 2010 Duramax trucks do to beef up their stock motor mounts and avoid the potentially damaging and power-robbing effect of driveline lash? Lucky for you, the team at Merchant Automotive has a solution that will help cure that driveline lash, put more power to the ground and prevent potential damage to other critical engine components.

We’re going to cover everything you need to know about upgrading your stock motor mounts in your 2001 to 2010 Duramax truck:

1. What does a motor mount do?
2. What is driveline lash?
3. How can motor mounts become damaged?
4. How can you tell a motor mount is damaged?
5. How do upgraded motor mounts work?

Trust us, if you own a 2001 - 2010 Duramax, you’re going to want to know more about these crucial engine components.

What Does a Motor Mount Do?

The motor mount is essentially a suspension for your engine.

Much like your tires, shocks and springs move up and down to keep your truck planted on the road, the motor mount functions in much the same way. It consists of a metal bracket and in the case of most stock motor mounts, a rubber bushing that is sandwiched in the center of the mount.

The motor mount is bolted to the frame of your truck in order to give it a firm anchor point, with the other side bolted right to your engine. The rubber bushing sits right in the middle.

This rubber bushing absorbs the vibrations from the engine, as well as allowing movement of the engine when it’s under a heavy load. Yes, your truck engine moves on its own with the magic of centrifugal force and actually rocks back and forth on the mounts! Here’s a video of the 6.6L Duramax being revved at a stop to illustrate the rocking motion.

Your motor mounts also perform another crucial function: supporting the engine while under load. As you accelerate, your entire drivetrain actually twists from the force being applied through the tires and this twisting can be seen from the engine to the rear of the truck.

The entire system is designed with tolerances that allow some twisting and as the drivetrain twists under load, some of that force that should be moving your truck forward is being transferred right into the motor mounts themselves. Again, this is the normal operating procedure for a motor mount but over time, this stress can cause the mounts to spectacularly fail. The more force, the quicker those mounts will give up the ghost.

What is driveline lash?

Remember that twisting we talked about above? This is known as driveline lash.

Driveline lash happens in high-horsepower, high-torque applications like the Duramax. As the tires hook up and move the truck forward, the entire driveline (axles, driveshaft, transmission housing, and motor mounts) all flex in response to the torque that’s being put to the ground. As noted above, this action is purposeful and allows your truck to minimize noise, vibration, and harshness while also providing ample capability. For most drivers, this situation never presents a problem.

When driveline lash does become a problem is under more extreme conditions that can push the stock driveline to its limits. Towing heavy loads produces extreme amounts of twisting in the driveline due to the extreme application of power to get your truck moving from a dead stop vs. the resistance of the load. Duramax owners who upgrade their engines to produce more power and torque will also see increases in driveline lash and almost certainly end up with damaged mounts.

How can motor mounts become damaged?

Over time, driveline last can wear out the rubber bushing in your motor mounts and cause them to rip or completely separate from the metal in the bracket. Once this happens, another whole can of worms is opened that could end up trying both your wallet and your sanity!

RIP Motor Mount

Not only will a busted engine mount let vibration and harshness creep into the cab of your truck but it will also put stress on other parts of your driveline because the mount itself is no longer able to shoulder the load. It’s like running your truck on a broken shock, you can still do it but your axles, tires, and spleen will all take a beating.

On Duramax trucks, the victim of this additional load is typically the transmission bell housing, which when flexed too much can crack. This is an expensive fix and not one you typically want to deal with.

How Can You Tell A Motor Mount Is Damaged?

If you suspect that you are dealing with a broken motor mount, there are several symptoms that indicate a motor mount has bit the dust:

1. Impact noises coming from the engine bay. These noises are usually described by drivers as clangs or bangs that can often be felt inside the vehicle. This happens as the engine shifts and makes contact with surfaces in your engine bay.
2. Excessive vibration. As we noted, a motor mount functions as a suspension/dampener for your entire engine and if the motor mount has failed, you will certainly feel excessive vibrations while in the cab of the truck, especially in a Duramax application.
3. Engine movement. Is it drooping to one side? Run the engine with the hood open and have a friend hit the gas, is your engine moving excessively or can you see if impacting other surfaces as it rocks back and forth? If so, your motor mount is toast.

Also, keep in mind, performing a visual inspection on a motor mount can prove quite challenging, as a broken mount doesn’t always indicate failure until it’s removed and inspected. Regardless, if you are experiencing one of the above symptoms, the culprit may be a busted motor mount.

How do upgraded motor mounts work?

Upgraded motor mounts like those offered by Merchant Automotive work by beefing up the bracket construction and by swapping out the rubber bushing in the stock mount for a more durable polyurethane bushing that better resists movement under heavy loads. Stock mounts are always built to a cost and put driver comfort above other criteria. These ultra-durable mounts are built to a higher standard of specification than any stock mount could ever hope for.

Merchant Automotive mounts will make your truck feel more locked down and ensure that more power gets to the ground and that potential damage to the mount, as well as other components, is all but eliminated due to the durable, flex-resistant construction.

Take a look at our video here. You’ll notice there is absolutely minimal shifting of the engine once our mounts are installed!

Models: 2500HD 3500 Chevrolet Silverado or GMC Sierra

Engine: 6.6L V8 Duramax diesel

Years: 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010

Trust The Duramax Experts

For nearly 20 years, we have dedicated ourselves to becoming the absolute expert in Duramax and Allison equipped trucks. From parts and upgrades that are designed and manufactured in house to impeccable standards, to offering a wide selection of tools and fluids to get the job done right; our team of experts is here to offer you the help and guidance you need so you can get back on the road confidently.