77 K20
Full Access Member
- Joined
- Nov 9, 2012
- Posts
- 3,121
- Reaction score
- 3,195
- Location
- Montana
- First Name
- Mike
- Truck Year
- 1977
- Truck Model
- K20 5" lift
- Engine Size
- HT383 fuel injected
My truck seems to be doing odd things lately. This one was a new one...
For 10 years I have driven the truck and not had this happen- but yesterday it was about 70 degrees here and did some exploring in the forest service all day long. It took longer to get back to the main road than I thought and then was going to be late for an appointment. I drove 75 mph on the highway for about an hour. (My speedometer doesn't work that well- lots of bounce. But engine RPM was 3,500. Truck has 4.10 gears) When I stopped I wondered why I smelled oil. Looked under the truck and the rear diff is covered in oil. The vent line comes out of the diff and is mounted to the underside of the bed right over the diff. Oil had gushed out of the vent tube and spilled down on the axle. I'm guessing maybe about a cup was lost?
I've driven it at 65 mph for 4 hours straight before without this happening.
Only thing different lately was I had by old summer tires mounted on new wheels and installed a few days ago. Tires were marked on where they came from and needed to be rotated. They rotated the passenger side but not the drivers side. My rear tires do wear faster than the front as it has a detroit locker in it. I'm guessing there might be a very slight difference in rear tire height, but that shouldn't make a locker heat up right?
Or I do have the exhaust cut off and dumps on the ground before the rear axle. Would 3,500 RPM be a "blast furnace" of heat to the rear axle?
Today or tomorrow I'll rotate the driver side tires and add fluid to the rear diff again. Just enough for it to start to spill out the add tube. Fluid back there was only about a year old. Conventional 80-90 weight. Directions for the detroit locker said not to use synthetic.
For 10 years I have driven the truck and not had this happen- but yesterday it was about 70 degrees here and did some exploring in the forest service all day long. It took longer to get back to the main road than I thought and then was going to be late for an appointment. I drove 75 mph on the highway for about an hour. (My speedometer doesn't work that well- lots of bounce. But engine RPM was 3,500. Truck has 4.10 gears) When I stopped I wondered why I smelled oil. Looked under the truck and the rear diff is covered in oil. The vent line comes out of the diff and is mounted to the underside of the bed right over the diff. Oil had gushed out of the vent tube and spilled down on the axle. I'm guessing maybe about a cup was lost?
I've driven it at 65 mph for 4 hours straight before without this happening.
Only thing different lately was I had by old summer tires mounted on new wheels and installed a few days ago. Tires were marked on where they came from and needed to be rotated. They rotated the passenger side but not the drivers side. My rear tires do wear faster than the front as it has a detroit locker in it. I'm guessing there might be a very slight difference in rear tire height, but that shouldn't make a locker heat up right?
Or I do have the exhaust cut off and dumps on the ground before the rear axle. Would 3,500 RPM be a "blast furnace" of heat to the rear axle?
Today or tomorrow I'll rotate the driver side tires and add fluid to the rear diff again. Just enough for it to start to spill out the add tube. Fluid back there was only about a year old. Conventional 80-90 weight. Directions for the detroit locker said not to use synthetic.
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