Aluminum Differential Cover Thermal Results
I recently installed a finned aluminum differential cover from PML Covers on my 2012 Chevrolet Avalanche 1500 that I intend to use for towing a travel trailer. In my previous truck, I had to replace ...
Forum Discussion
Agree with Turtle...it looks like corrosion damage...NOT extreme pressure. They do their dirty work differently.
Corrosion will pit by eating and pressure will flake the surface metal by work hardening
Also ask if that diff ever got underwater when it was HOT...and check your vent valve...it is supposed to prevent drawing in water (one metric...other is to vent when it gets hot).
OR you have somehow gotten water into the diff
There are other things going on that the thermal images shows
The axle tubes are also part of the heat rejection system. Heat sink in mass to absorb, hold and reject via surface area. The why it isn't that hot as you move farther away from the heat source...the gear teeth
Since ALU is a better conductor, it will reject more heat. Thickness in this case not really a component, as the lube is in direct contact with the cover. Therefore will show hotter. It is also insulated in part from the pumpkin by the gasket (reduced thermal transfer surface area) and heat will be wicked away to the pumpkin/tube material, which is larger in mass
There are anti-foaming additives in all diff lube, but it still foams a bit. The hotter it gets, the more it will foam. Foam has lots of air bubbles, which is NOT as good a thermal conductor as the lube itself. This and the fact that the flow of diff lube isn't very good going down each axle tube has the tube able to cool it way faster than the input (new, hot lube going down the axle tube)
Corrosion will pit by eating and pressure will flake the surface metal by work hardening
Also ask if that diff ever got underwater when it was HOT...and check your vent valve...it is supposed to prevent drawing in water (one metric...other is to vent when it gets hot).
OR you have somehow gotten water into the diff
There are other things going on that the thermal images shows
The axle tubes are also part of the heat rejection system. Heat sink in mass to absorb, hold and reject via surface area. The why it isn't that hot as you move farther away from the heat source...the gear teeth
Since ALU is a better conductor, it will reject more heat. Thickness in this case not really a component, as the lube is in direct contact with the cover. Therefore will show hotter. It is also insulated in part from the pumpkin by the gasket (reduced thermal transfer surface area) and heat will be wicked away to the pumpkin/tube material, which is larger in mass
There are anti-foaming additives in all diff lube, but it still foams a bit. The hotter it gets, the more it will foam. Foam has lots of air bubbles, which is NOT as good a thermal conductor as the lube itself. This and the fact that the flow of diff lube isn't very good going down each axle tube has the tube able to cool it way faster than the input (new, hot lube going down the axle tube)
