PML Differential Cover - Install and Review

Waterfowler41 · August 6, 2018

Finished up my PML diff cover about a week ago and figured I would post my thoughts on the part and the install.

Overall the installation is easy. If you can change your oil, you can change your diff cover. Link to the cover: https://www.yourcovers.com/diffcover_11129.php

About the cover: The PML cover increases the oil capacity of the rear diff by about 0.4-0.6 quarts. Part number 11129 comes in 3 finishes; standard silver, black powder-coat, and chrome. I opted for the black powder-coat cover. It fit well with my truck's theme and wasn't too showy. Its made out of aluminum and in conjunction with the cooling fins, allows your diff to run cooler. The cover fits the 9.5" ring gear in the standard rear diff and the 9.75" ring gear available with the max tow package. The covers comes with stainless steel allen head bolds and washers along with a plug for the fill hole and a stainless/magnet drain plug. Fit and finish were on point, not one issue with the installation.

Install: Along with the diff cover you will need:

4 quarts of oil, 75W-90
Oil pump
Drain pan
Medium strength threadlocker (the blue stuff)
Optional: RTV gasket maker if you do not want to reuse your OEM gasket

Make sure truck is parked on level ground.
Remove the (12) 10-mm bolts around the OEM cover. Remove all but two; leave one bolt finger tight on the bottom and one bolt finger tight on the top to allow a controlled drain of the oil.

Inspect the OEM gasket, if you see any damage it should be replaced by RTV gasket maker.
Use a razor blade to clean the mating surface of the diff cover making sure any oxidation is cleared off. Shouldn't be any if you were using the OEM gasket.

Install the diff cover by carefully threading the bolts through the cover into the diff housing. Use blue threadlocker on each bolt. The bracket holding the emergency brake cable will need to be bent upwards to allow for cable clearance over the top cooling fin.
Use the longest bolt in the pack in the hole for the brake cable bracket. All other (11) bolts are the same size.
Tighten the bolts in a star pattern like you do with wheels. Tighten drain plug. Torque appropriately.
Fill the diff casing by pumping oil. Continue pumping oil into the casing until it starts to spill out of the fill hole.
Close up drain plug and wipe down the casing. If you used your OEM gasket you're good to go to drive. If you used RTV gasket maker than you should wait a few hours to let the gasket maker set up.

And for good measure, here's my video of the installation! Again very happy with the cover. The cover looks great and is extremely functional for those of us that tow quite regularly.

Willie will · August 6, 2018

Great write up bro. Guess I’ll put that on my list to do lol

WSFD6107 · August 6, 2018

Thanks Britt!!!!!

Now, not only do I have to purchase and install my Bumpershellz, but I also have to purchase and install a new Diff cover. Thanks for sharing your experience. (Still recovering financially from the Disney trip) Jason.

Sierra Dan · August 6, 2018

Great Post and Review

And a nice looking cover.

Waterfowler41 · August 6, 2018

Thanks Britt!!!!!
Now, not only do I have to purchase and install my Bumpershellz, but I also have to purchase and install a new Diff cover. Thanks for sharing your experience. (Still recovering financially from the Disney trip) Jason.

You need both!!!!

Waterfowler41 · August 6, 2018

Great write up bro. Guess I’ll put that on my list to do lol

It’s been on my list a while, felt good to check it off! Now on to shocks!

Waterfowler41 · August 6, 2018

Great Post and Review

And a nice looking cover.

Thanks!

Sierra Dan · August 6, 2018

23 minutes ago, WSFD6107 said:

Thanks Britt!!!!!

Now, not only do I have to purchase and install my Bumpershellz, but I also have to purchase and install a new Diff cover. Thanks for sharing your experience. (Still recovering financially from the Disney trip) Jason.

Are you sure the recovery is not Emotional related, rather than financial? LOL

Been to the 8th gate of hell myself.

Waterfowler41 · August 6, 2018

Are you sure the recovery is not Emotional related, rather than financial? LOL
Been to the 8th gate of hell myself.

It’s a small small world after all....

CDNSS · August 6, 2018

It only ads 1/2 qt ?? Or did I misunderstand not sure if that is enough to lower diff temp enpugh when towing heavy loads non stop for hours with 1500 diff

i used the Mag Hytec cover it added at least 2 qts and no gasket needed has an integral o ring Instead of gasket. Dipstik and temp sensor port I was burning up pinion bearings until I added larger cap cover check my temps on long tows now never an issue

Waterfowler41 · August 6, 2018

It only ads 1/2 qt ?? Or did I misunderstand not sure if that is enough to lower diff temp enpugh when towing heavy loads non stop for hours with 1500 diff

i used the Mag Hytec cover it added at least 2 qts and no gasket needed has an integral o ring Instead of gasket. Dipstik and temp sensor port I was burning up pinion bearings until I added larger cap cover check my temps on long tows now never an issue

Does mag hytec make a cover for the 12 bolt gm rear on the 1500’s?

Jon A · August 7, 2018

1 hour ago, CDNSS said:

i used the Mag Hytec cover it added at least 2 qts and no gasket needed has an integral o ring Instead of gasket. Dipstik and temp sensor port I was burning up pinion bearings until I added larger cap cover check my temps on long tows now never an issue

How much farther than stock does the Mag Hytec protrude from the axle? One thing for people to consider, if you have a larger than stock spare tire the diff cover could interfere if it sticks out far enough.

I agree a larger capacity should result in even lower temps, but the cooling fins alone on the PML should reduce temps from stock substantially.