Posted by Smooth Operator on November 09, 19100 at 10:48:57:
In Reply to: How hot it gets posted by Ben on November 09, 19100 at 09:56:56:
: Here's an actual account on how hot these things get. In the summer of 99 I was going to tow my brothers 6,200lb boat to Chincoteaque Va. from NJ with my 89 2500 Sub w/4:10 rear. He was towing my pop-up camper since his Ford Bronco was not up for a long distance towing job like that. From this point it would have the heaviest load I pulled to date. A week before leaving on the trip I did a test tow and also had the rig weighed on the scales which was 12,400lbs with truck, boat/trailer, and driver. On the way home from my brothers house doing the test tow, and it being the hottest day (99F)of the year so far, I was driving down the Garden State Parkway keeping an eye on all the guages, the rig, and where I was going. All of a sudden a huge cloud of blue/white smoke emitted from underneath the rear of the vehicle. I immediately pulled over thinking I blew something up although there was no large noise accompanying the smoke. Looked underneath and could find no evidence of a blown pinion seal or major oil leak. Touch the pumpkin on the differential and WAS IT HOT! Like an exhaust manifold.
I limped home with no further evidence of trouble and had the differential checked out by the dealer and he said everything was Ok so I specified to have the unit flushed and filled with synthetic (Thanks for that advice Ben) and had it button up. Took off on my trip loaded adding family and gear plus a Sunfish sailboat on the roof and had no more trouble. I believe the dino oil in there got so hot it must have boiled, shot out of the vent tube and sprayed my exhaust for the pyrotechnic show.
In addition , pryor to the trip I had my transmission serviced and installed the biggest baddest trans oil cooler that would fit. My TH400 never missed a beat! I miss that old sub.
Moral of the story:
If you are going to put your truck to work, use synthetics, do the maintenance, and always to a test run so you won't ruin your vacation.
SO
Good thread to raise consciousness of this part of the vehicle, which is one of the most neglected components in a vehicle.
: Many don't know the level of stresses a diff has, nor how hot it gets when everything is working right. Even hotter when things go wrong and is one thing I use as an indicator of how things are going there.
: Take a look and you'll see that most have the paint burned off or is peeling from heat of the rear diff cover.
: Another thing to watch out for in clutch type is the wear to the carrier cavity housing the clutch pack. If the fluid isn't changed often enough in realtionship to usage, it will wear and any rebuild without additional shims will have the clutches slip creating additional heat.
: I've never done one because my first attempt was stopped by my teaching buddy. I'm just plain not good at this is what he said and I've not touched one since, other than to do a "C" clip or cleanout.
: -Ben