How to Drain and Refill a car Differential
Note Drain plug position
Servicing a differential isn’t a job that needs done too often. However, it does need done as preventative maintenance or if the vehicle was in deep water which could have allowed water to enter the differential. Also, over the years and miles, the differential gasket can get dry causing leaks. We recommend that if there are no leaks, that you follow themanufacturer’s recommended service intervals. They can be found in the vehicle’s owner’s manual. Note: Locate the fill plug on the differential.
Chrysler products use a round, black rubber plug on the cover. Other manufactures use a threaded plug that can be located on the cover or on the differential housing. Make sure you are able to remove the plug before you begin the process. Many times the threaded ones will rust in place. If you are unable to remove the plug, you will not be able to refill the differential when you finish. If that is the case, you may need special tools to remove it.
Park your car on level ground with the engine off and the emergency brake on. Always raise a car according to the manufacturers recommended instructions and secure with jack stands. Also we will be dealing with gear oil so be sure to wear protective clothing, eyewear and gloves.
Full drain losen all bolts
Tools and Supplies Needed
1. Floor Jack
2. Jack Stands
3. Ratchet / Sockets
4. Screw Driver Set or Pry Bar
5. Drain Pan
6. Shop Towels
7. New Differential Cover Gasket
8. Gear Oil
9. Gasket Scraper
Step 1 - Place a large drain pan under the differential. Make sure it is larger than the differential and is able to hold all the gear lube in the differential. Allow the drain pan to stay in place until the job is finished to capture all gear lube.
Step 2 - Begin by loosening all the bolts holding the differential cover. Loosen them approximately two turns each.
Step 3 - Next, remove the bottom bolts.
Step 4 - Carefully, so you don’t make a mess, take your pry bar or screwdriver and gently pry out on the bottom of the cover so it opens slightly. Allow the gear lube to slowly drain into the drain pan.
rear view if no front cover access
Step 5 - Once the bulk of the oil has drained, remove the remaining bolts and remove the cover.
Step 6 - Using a clean rag, wipe all remaining oil from the differential and clean the inside of the cover. NOTE: Some covers will have a magnet attached to it to collect metal shavings. Make sure to clean it too. Brake cleaner is a strong cleaner that is helpful in cleaning the dirty parts. However, make sure to use it in a well ventilated area.
Step 7 - The old gasket material will need removed. Use a gasket scraper to clean both the differential housing and the cover. Make sure both surfaces are clean, dry, and free of old gasket material.
Step 8 - Next, inspect the cover for any damage where the bolts held it in place. If it is warped, a leak can occur.
Step 9 - Lay the differential cover on the floor (internal side facing up) and align the new gasket with the bolt holes. Place two of the bolts through the back side of the cover to hold the gasket in place.
Step 10 - Carefully, align the bolts with the correct holes on the differential housing and hand tighten them.
Step 11 - Install the remaining bolts hand tight.
Step 12 - Using a star pattern, tighten the cover to the manufacturer’s recommended torque or snug.
Step 13 - Remove the fill plug and refill the differential with the manufacturer’s recommended gear oil lube. Many require a standard GL-5. However, we recommend referring to the owner’s manual orservice manual for manufacturer recommendations.
Step 14 - The differential is full when the gear lube reaches the bottom of the filler hole. You will know because the gear lube will begin to leak back out. Once you think it is full, stop adding and allow the excess to leak from the filler hole. Replace the fill plug, clean up any gear lube from the work area, lower the vehicle, check for leaks, and the job is done. Althoughreplacing the differential fluid isn’t required too often, it still needs to be done.
We recommend following the manufacturer’s service intervals located in the vehicle owner’s manual. Also, make sure to dispose of the old gear lube properly.
Look for a metallic sheen to the gear oil, this indicates there might be a bearing that has failed or is starting to fail.
Inspect the wear pattern on the face of the ring and pinion gears teeth. The wear pattern should be in the middle of the tooth. If the wear pattern goes off the top tooth the gears are worn.