Front Differential Issues after engine modifications

[Doghouse Dweller]

Yo! I have a 2004 Yukon Denali with a LQ4 6.0, 4L65E with 258,000 miles. At 255,000 miles I swapped the heads for 706s, installed a Truck Norris cam, long tube headers, 44lb fuel injectors and a 2800 stall torque converter. Shorty after the build my front differential became super hot and puked black gear oil out the vent. I changed the oil and drove it another 3 months at which point it starting making a growling noise. The oil looked like black metallic paint. I knew the diff was done, so I installed an overhauled unit and now after a 25 mile drive its very hot to the touch. What could be causing my new front diff to get hot? Could worn out drive shafts or transfer case cause a diff to get hot and fail early? Could I have installed something incorrectly? I had no issues before the engine build? I'm not experiencing any other issues with the drivetrain except with the front diff.

 

[SpareParts]

Different tire sizes between front and rear?

 

[Joseph Garcia]

I'm sure that you checked up front, but I'll ask anyway.... Are the gears in the front differential the same as in the rear axle?

 

[SpareParts]

Another possibility. Could you have somehow hooked the diff vent line to something on the engine?
I have no idea what but weirder things have happened.

 

[rockola1971]

Notice any noise when turning, especially in a tight parking lot? Drain front diff and inspect for metal flake. Overhauled unit may have been improperly setup.

 

[Doghouse Dweller]

All good ideas! And I love the profiles! The temp was hot to the touch, I couldn't put a hand on it for more than 3 seconds. I asked google what the normal operating temps are for an AWD front diff and it said 170 to 220. 170 is about a 3 second touch, so I'm just keeping an eye on it for now. But, man, I did everything a DIY'er could do to inspect and check everything related. As far as I can tell, the front end is true as it can possibly be. Thanks for all the suggestions!

 

[swathdiver]

Yo! I have a 2004 Yukon Denali with a LQ4 6.0, 4L65E with 258,000 miles. At 255,000 miles I swapped the heads for 706s, installed a Truck Norris cam, long tube headers, 44lb fuel injectors and a 2800 stall torque converter. Shorty after the build my front differential became super hot and puked black gear oil out the vent. I changed the oil and drove it another 3 months at which point it starting making a growling noise. The oil looked like black metallic paint. I knew the diff was done, so I installed an overhauled unit and now after a 25 mile drive its very hot to the touch. What could be causing my new front diff to get hot? Could worn out drive shafts or transfer case cause a diff to get hot and fail early? Could I have installed something incorrectly? I had no issues before the engine build? I'm not experiencing any other issues with the drivetrain except with the front diff.

If the ring and pinion are tight or any other bearings too tight, they'll generate heat until they wear in or destroy themselves.

What did you set the rotational torque and backlash to? Did you replace the gears or just the bearings and seals?

 

[Doghouse Dweller]

If the ring and pinion are tight or any other bearings too tight, they'll generate heat until they wear in or destroy themselves.

What did you set the rotational torque and backlash to? Did you replace the gears or just the bearings and seals?

I installed an overhauled front differential from Powertrain Products Inc. I'm following the break-in instructions that came with the assembly. so far so good....

 

[Geotrash]

If the ring and pinion are tight or any other bearings too tight, they'll generate heat until they wear in or destroy themselves.

What did you set the rotational torque and backlash to? Did you replace the gears or just the bearings and seals?

^^^This^^^

Newly overhauled differentials will get hotter than normal until the gears get broken in, typically within 200-500 miles. If the backlash wasn't set right, you should find out within the warranty period when it eats itself. If after 500 miles it's still getting that hot after a short 10-15 mile drive, then I would start to get concerned.