This is a common S-truck and S-Blazer issue that if not caught soon enough can wipe out the otherwise reliable 700R4 or 4L60E transmissions in these vehicles. Fortunately, if you check your trans fluid on a regular basis, you'll notice it right away. Around 120,000 miles, I was driving my wife's Blazer when we stopped for fuel and I just decided to check the fluid. It was two quarts low. I had gone through this with two earlier S-vehicles so I immediately called my mechanic and scheduled a service call. The problem is that in the output end of the transmission that goes into the transfer case, there is a seal that gets rock hard due to heat. At some point, it no longer holds onto the fluid, and due to the tilt of the transmission, it allows it to drain into the transfer case, overfilling the transfer case and allowing the remaining fluid in the transmission to overheat. My mechanic pulled the trans, drained the transfer case to the correct level, replaced the seal, and put it all back together.
Symptoms of this problem include trans fluid blowing out of the transfer case vent line in the underhood space, and loss of transmission fluid with no external evidence (no puddles under the vehicle, but fluid level keeps dropping). The fix is simple, and will save you expensive repairs.
A D V E R T I S E M E N T S
This is a common S-truck and S-Blazer issue that if not caught soon enough can wipe out the otherwise reliable 700R4 or 4L60E transmissions in these vehicles. Fortunately, if you check your trans fluid on a regular basis, you'll notice it right away. Around 120,000 miles, I was driving my wife's Blazer when we stopped for fuel and I just decided to check the fluid. It was two quarts low. I had gone through this with two earlier S-vehicles so I immediately called my mechanic and scheduled a service call. The problem is that in the output end of the transmission that goes into the transfer case, there is a seal that gets rock hard due to heat. At some point, it no longer holds onto the fluid, and due to the tilt of the transmission, it allows it to drain into the transfer case, overfilling the transfer case and allowing the remaining fluid in the transmission to overheat. My mechanic pulled the trans, drained the transfer case to the correct level, replaced the seal, and put it all back together.
Symptoms of this problem include trans fluid blowing out of the transfer case vent line in the underhood space, and loss of transmission fluid with no external evidence (no puddles under the vehicle, but fluid level keeps dropping). The fix is simple, and will save you expensive repairs.
- r a, Albuquerque, NM, US