New Duramax Motor Mounts From Merchant Automotive

With a few bolt-ons and some tuning, it’s pretty easy to get a lot of power and torque out of the Duramax engines that GM has delivered in the Chevrolet Silverado and GMC Sierra beginning with the 2001 models. Unfortunately, the factory rubber motor mounts are not up to the task of keeping the engine solidly located between the frame rails. In many cases, we see the factory mounts fail with stock power levels and they can literally be ripped apart by big-power trucks. Of course, if the engine is twisting around in the chassis, it’s putting more stress on the transmission case and mount, and potentially damaging external engine components from contact.


Rather than simply replacing the factory rubber mounts each time they fail, the team at Merchant Automotive (MA) in Zeeland, Michigan, has developed a permanent motor mount solution. The MA High Performance Motor Mounts are fabricated in-house from plate steel that’s precision TIG welded in two halves. These two halves are then united by high-grade fasteners and polyurethane bushings to keep even high-power Duramax engines firmly in place. The mounts are powder coated in Merchant Automotive’s signature bright orange to protect the steel.

We visited Merchant’s shop and followed along as shop technician Jake Phaff installed a set of MA High-Performance Motor Mounts on shop fabricator Joe Beaudoin’s newly purchased 230,000-mile 2003 GMC Sierra 2500HD. Ironically, Beaudoin is the welder who fabricates the motor mounts, and he knew that the high-mileage truck he purchased needed a set of mounts. Upon inspection under the hood, you could literally watch the motor rock back and forth when the engine was revved, even with the truck in park.

After removing the factory mounts, we found that they had completely failed with the rubber that fuses the two mounting plates together torn away. The failure meant that the engine was really just sitting on rubber pads and not truly bolted to the chassis.

1 Joe Beaudoin works for Merchant Automotive as a shop fabricator. Here’s he’s TIG welding a pair of motor mounts just like those that will go on his own truck.

2 Here’s an up-close look at the components that make up the robust MA High Performance Motor Mounts before the halves are powder coated. With high-grade hardware and polyurethane bushings, these mounts are sure to keep your Duramax engine secure within the frame rails.

3 The complete MA HP Motor Mount kit includes both powder-coated two-piece mounts, high-grade mounting hardware, thread locker and even a die-cut multi-color decal to show off your Merchant Automotive pride. These mounts are designed to hold your Duramax in place, even if the bushings wear out completely.

4 To get the installation started, Jake Phaff lifts the truck on a two-post lift then removes both front wheels to easily access the fender wells. Next, he removes the plastic fender liner from each side, being careful not to damage the plastic retaining clips.

5 On the driver side, he disconnects the steering shaft at the coupler (see arrow) to make it easier to work in the tight space.

6 The driver-side boost tube will be removed for additional room to work. Disconnect the top side at the turbo outlet and then the lower side at the intercooler boot as seen here.

7 With the clamps loosened at each end, Phaff can snake the boost tube out of the fender well.

8 A visual inspection of the driver-side factory motor mount looks fine when it’s sitting still and has the weight of the engine pressing down on it. The condition can be deceiving. If your truck has high mileage or you see the engine rocking under the hood there’s a good chance that the mounts are toast even if they “look” good.

9 Phaff removed the three mounting bolts securing the motor mount to the frame bracket. This allows the engine to be raised.

10 Then, using a muffler jack, he carefully lifts the driver side of the engine to allow the mount to be unbolted from the engine and removed.

11 After removing the four mounting bolts securing the motor mount to the engine block, Phaff removed the factory motor mount.

12 & 13 Despite looking okay when the engine was at rest, when removed from the truck it was easy to see that the stock motor mount had completely separated where the rubber was fused to the steel. The damaged stock motor mounts are seen here next to the more robust MA mounts.

14 Phaff separates the top and bottom halves of the MA mounts to make it easier to install the mounts into the truck.

15 Phaff uses thread locker to make sure the bolts do not get loose and back out.

16 He installs the top half of the MA mount to the engine block first.

17 After running in the bolts by hand, Phaff uses an impact gun with a long extension to tighten the four upper motor mount bolts from below the truck.

18 Phaff then reunited the lower half of the MA mount with the upper half.

19 He aligned the halves, then inserted the through bolts from the front before installing the nuts with thread locker to prevent them from loosening.

20 & 21 Next, he reinstalled the frame bracket and gently lowered the engine until it was close enough to start the lower mounting bolts (see arrow) to make sure they properly align before fully lowering the engine. Be sure to use the supplied thread locker on all of the mounting bolts and nuts.

22 He then uses the impact gun to tighten the bolts.

23 The passenger side is handled in the same basic manner as the driver side except there are fewer obstructions, so it’s easier to unbolt and remove the old mount even from above the frame rail.

24 As on the driver side, Phaff separated the top and bottom halves, then reunited them in the truck, making sure to use thread locker on all the mounting bolts and nuts.

25 If you separated the steering shaft, be sure to reconnect it before buttoning up your installation. Otherwise, you may have some problems getting out of the driveway.

26 Phaff reinstalled the boost tube through the fender well and reconnected it to the intercooler boot.

27 He then reinstalled both of the plastic fender liners as well as the front wheels.

28 Phaff slips the boot over the turbo outlet and tightens the clamp to complete the installation.

With the aid of the two-post truck lift and a muffler, jack Phaff was able to remove the worn-out factory mounts and replace them with a new set of Merchant Automotive mounts in about two hours, including time for our typical photography slowdowns. While it’s easier to work on and shoot photos when performing the upgrade on a vehicle lift, this is also a project that can be done in your garage or driveway using a quality set of heavy-duty jack stands and a good floor jack. If you choose to perform the installation yourself be sure to practice safe shop techniques, especially when working below the truck.

With the bright orange finish and polished MA logo, these motor mounts are undoubtedly good-looking parts for your Duramax-equipped truck, but unfortunately when they’re installed they can barely be seen. So if you’re looking to add some bling to your truck this might not be the right product for you. However, if you want to lock down your Duramax engine solidly into your truck’s chassis so that it doesn’t rock around like a boat in rough seas, the Merchant Automotive High Performance Motor Mounts are the product for you and your truck. Installing a set in your GM truck will help to ensure that the engine stays firmly in place and help to transmit all of the power to the driveline. DW

Merchant Automotive