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Transmission seals keep fluid inside where shafts pass through the case, and Route 66 Auto Repair in Upland replaces them when they harden, crack or wear. There are several seals, and they differ a lot in effort. An axle seal can be a quick job. A front pump seal means removing the transmission. Our ASE-certified technicians identify which seal is leaking and explain the work before you approve it.
Which transmission seals leak most often?
- Axle seals on front-wheel-drive cars, where the drive axles enter the transmission
- Output shaft seal at the rear on rear-wheel-drive trucks
- Front pump seal between the engine and transmission
- Shift shaft seal where the linkage enters the case
- Sensor O-rings on speed and range sensors
Why does seal location change the job so much?
Axle seals are replaced after pulling the axle, which often needs a wheel bearing and suspension check anyway. Shift shaft and sensor seals are reachable from outside. The front pump seal sits behind the torque converter, so the transmission must come out, and we often inspect the converter and pump bushing at the same time.
We also ask why the seal failed. A worn bushing or bearing lets the shaft wobble and will ruin a new seal quickly. Those checks are part of the job. Rear seals on trucks are covered on output shaft seal replacement. If you are not sure where your leak is, start with transmission fluid leak repair.
Our seal replacement process
Step 1: Confirm the seal
We trace the leak to a specific seal and photograph it.
Step 2: Check for shaft play
The shaft, bushing or bearing behind the seal is checked for wear.
Step 3: Replace the seal
The old seal is removed without scoring the bore and the new one is installed straight.
Step 4: Refill and verify
Fluid is topped off and the seal is checked after a road test.
What's included in seal replacement
Included on the work order
- 01Leak source identification with photo
- 02Shaft and bushing play check
- 03New seal of the correct type
- 04Related parts removed and reinstalled as needed
- 05Fluid top-off to the specified level
- 06Road test and leak recheck
Which seal leaks need attention now?
Need now: call
- A front pump seal leak that is getting worse
- An axle seal dripping on a brake or CV boot
- Any seal leak dropping the fluid level
Need later: book
- A shift shaft seal that is only damp
- A sensor O-ring seep with a steady level
How seal pricing works
The seal part is usually small. Labor is the difference, and it depends on what must come off to reach it. The written estimate names the seal, the parts removed and the fluid. If we find worn bushings, we stop and call before adding them. Outside seals often finish the same day when the board allows.
After seal replacement
A little residue may drip for a day. Fresh spots after that are worth a return visit. If the transmission came out for a front seal, we check mounts and connections again at your next oil change.
Frequently asked questions
Can a seal leak cause transmission damage?
Yes, if it drops the fluid level. Low fluid means slipping and heat. That is why we treat level-dropping leaks as need-now.
Why replace the front seal with the transmission out?
There is no other way to reach it. When it is out, we check the converter hub and pump bushing too, so the new seal lasts.
Do axle seals come with a new axle?
No. Seals are separate parts. If an axle is being replaced for a torn boot, replacing the seal at the same time is smart, and we will quote it.