8 3/4 323 surgrip, what is normal temp for the pumpkin during normal driving?

[Back N Black]

I drove my charger for 30 min on the highway at 75 mph and when i got back home i put my hand on the pumpkin and could hold there for about 5 sec before it got uncomfortable. I'm losing oil out the diff vent?

[firefighter3931]

It sounds like there's a bearing issue going on in the centersection.

What type of lube are you using Eldon ?

Overflow out the vent means it's overfilled or something is causing the lube to overheat and expand 



Ron

[Back N Black]

It sounds like there's a bearing issue going on in the centersection.

What type of lube are you using Eldon ?

Overflow out the vent means it's overfilled or something is causing the lube to overheat and expand 



Ron

I have 80/90 weight gear oil with the dealer additive.

[flyinlow]

This gave me a chance to use my lazer thermometer.

After a 30 mile run on the interstate with a 3.55 suregrip 742 axle . Mobil1 Gear oil + suregrip lube.

Temps:   145-155 * F  highest temp near pinion. Axle uncomfortable to touch for long. 80* day.

Any chance you have gotten water in the axle?

Check fluid level.

Might consider changing the gear oil . I would before I would start looking for a problem if its not making noises. 

[Sublime/Sixpack]

I've never really thought about what the normal operating temperature of these units would be. Now I'm curious. I'll break out the laser thermometer next time I take the car out.

[elacruze]

"Further evidence of stress and increased temperatures during the differential break-in period is documented in a 2005 SAE paper entitled The Effect of Heavy Loads on Light Duty Vehicle Axle Operating Temperature. A light duty GM truck towing 14,000 pounds was driven from Orange County, Calif. to the Nevada state line. The test was conducted with both a new axle and a broken-in axle. Over level ground towing, oil temperature was measured at 230 degrees F in the new axle and 203 degrees F in the broken-in axle. Oil temperature over the most grueling portion of the trip, during which a maximum 6% grade was encountered, revealed the new axle was operating at 350 degrees F and the broken-in axle was operating at 300 degrees F. Laboratory dynamometer test results simulating a truck hauling a trailer provided similar results, with level ground towing temperatures recorded at 266 degrees F with the new axle and 194 degrees F with the broken-in axle and towing temperatures (at a 3.5% grade) recorded at 370 degrees F with the new axle and 295 degrees F with the broken-in axle."

http://www.upmpg.com/lubricationnews/differential_maintenance/

Most commercial water heaters are limited by law to 150*F because that is below the scalding threshold. It is still extremely hot.
Put your hand on your upper radiator hose next time your car is up to temp, and compare that temp with your rear axle. You'll see that it is not nearly as hot as you probably think it is. The SAE paper cited above shows the normal operating temperature of a heavy loaded pickup to be ~250-~370*F. That's smokin' hot.
Ford F53 motorhome chassis rear axles are famous for getting hot enough to melt the sway bar bushings off. They're also famous for killing the gears if you don't service the lube by the book, too.

[flyinlow]

Interesting 

Did not think axles lube would see 300* +

I thought 150* was fine. Most of the time our axles are not working that hard. Not towing for long periods .



"Put your hand on your upper radiator hose next time your car is up to temp, and compare that temp with your rear axle. "



No thanks, I prefer to burn my hands on 98* female things!

[elacruze]

No thanks, I prefer to burn my hands on 98* female things!

It burns because you're wicked 

[Back N Black]

Thanks guys, lots of great info. I'm going to take the charger for a drive later today and check the temp with my lazer thermometer. I will keep you updated.

[Back N Black]

Took the Charger for a 30 min drive and checked temp with lazer thermometer, it was 150 F at the pumpkin and 105 F on the axle tubs. Seem normal but still oil out the vent tube? i will take a little more oil out and check again.

[y3chargerrt]

Did you seal the threads on the vent tube? They will leak oil if you don't use teflon on them.