Symptoms of Rear Differential Issues

Typically, there are two symptoms you’ll notice when you have a bad differential, or car differential problems:

Rear Differential Noise – if you hear howling from the rear of your truck or SUV when you’re driving, it’s possible it’s rear differential noise. It can change in pitch as well as come and go depending on the severity of the issue and load on the diff. Many times, rear differential noise is mistakenly thought to be tire noise and ignored, leading to more expensive repairs.
Rear Differential Leak – more commonly, the problems stem from low rear differential oil. Rear differential leaks are the culprit, either at the axle seals, the pinion seal (where the driveshaft attaches), or the rear differential cover. Light brown or grayish fluid on the ground under the back of your truck is an indication that you have a differential fluid leak. Rear differential leak repair costs can range depending on whether they are light repairs such as replacing the oil seal, or adjusting backlash, or if you need to overhaul and rebuild the differential.

Types of Rear Differential Repairs

Obviously, the less intrusive the repair is a rear differential oil leak before it causes other issues. Different oil leak repairs include:

Rear differential gasket replacement. The rear differential cover is typically silicone or rubber and can deteriorate and leak. It’s the easiest to repair – all that’s required is removing the rear differential cover, cleaning the sealing surface, and resealing the cover. It’s all done in less than an hour.
Rear differential pinion seal. At the front of the differential is a yoke that attaches to the driveshaft. The seal around the yoke can develop a leak over time, either from nicks in the rubber or from age. This can take a bit more time to repair as the yoke needs to be removed, the seal pried out, and a new seal driven into place without damaging it.
Differential side seals. These seals prevent the diff fluid from leaking onto your rear brakes. It’s more intrusive because the axle shafts must be removed. The old, leaking seals are pried out and new ones are carefully installed before the whole assembly is put together.

Rear differential bearing replacement. There are side bearings and a pinion bearing which can pit or deteriorate, causing your rear differential noise. These bearings are part of a rear differential overhaul, taking three to five hours to complete.
Replacing the rear differential gears. When teeth on the gears have chipped or worn badly, they must be replaced to eliminate the noise and potential for failure. These ‘hard parts’ are the costliest components, and repairs can only get one step worse.
Complete rear differential replacement. If the gears have ‘grenaded’, the case might not be salvageable. That’s when a complete rear differential replacement comes in – housing, gears, bearings, seals, and all.