This thread is in regards to the Ford Expedition, Ford F150, Ford F150 Raptor and Lincoln Navigator front differential problems in the 2021 through 2025 model year vehicles. Im posting this here because I want to be helpful to whoever finds it. There are a bunch of different threads on Reddit and in F150 forums about it.
My former vehicle was a 2023 Lincoln Navigator L and it developed a whirring noise which turned into a grinding noise. Every time I took it to the Ford dealership I kept getting the run around. One day I took it to an independent mechanic who was extremely helpful and way better than the technicians at the Ford dealership. He showed me the front differential. Fluid was black (out of a new bottle its clear) and there was a glittery silver metal running through it. He told me the front differential was literally eating itself. I took photos and went back to the Ford dealership. The next thing I knew they had my truck for over a month. When I got the truck back there was that noise again. Took the truck back to the dealership and they replaced the left wheel bearing...still there was that noise...took it back and they replaced the the right wheel bearing...still there was that noise. This eventually ended one day when I sold the vehicle to Carvana and got myself a 2025.
I thought all the problems of the 2023 "Covid trucks" were solved in 2025...little did I know that I was wrong. All of a sudden I heard that whirring noise. This time I took it to an independent mechanic to have a look. He told me the front differential was leaking and showed me the entire bottom was wet with gear oil. Furthermore he ended up adding gear oil stating there was only 1 quart of gear oil left in it. After that I drove it around and looked underneath. Sure enough there was a drip. I took it to the Ford dealership and after 1 hour their best technician took me aside, looked me in the eye and told me it was the fill plug...he told me there was not enough sealant on it. The gear oil was passing through the threads.
So I left the Ford dealership and take note I will never go to that one again. Either they were deliberately lying to me or they did not know what they were doing. I went right back to the independent mechanic and decided to take matters into my own hands. I spoke with the independent mechanic and asked if he knew where it was leaking and what he needed to do to fix it. Affirmative! He told me what he needed and that was "Permatex Grey". I enjoy being informed about these matters so I turned to the internet for a crash course on sealant. There is Permatex Ultra Grey and Permatex Optimum Grey. The Optimum Grey is an improved version of the Ultra Grey. I went around to 3 parts stores and finally found a single tube on the shelf of the Optimum Grey. Apparently Optimum Grey is a very popular product around here.
The "fix" the mechanic told me was to take off the metal cover on the differential...there are several bolts...and seal it with the Permatex. He pointed out there is no gasket between the cover and the differential. I looked on the Ford parts website and he was right. Somehow Ford thought it was a good idea to have no seal between the cover and the differential. (see attached image).
Yesterday the entire truck was left at the mechanic at 8am. On the Reddit and Permatex website there were certain ways to use these sealants to perfection. After use you really should not disturb it for at least 6 hours, but preferably 24 to 48 hours. After the work was done I opted to pickup the truck 15 minutes before the mechanic closed for the day allowing it to sit for at least 6 hours. I drove the truck right back to home which wasnt far and its been sitting in my driveway. Im going to try to leave it alone in the driveway until it reaches at least 24 hours from the time of installation. In various forums it was suggested to leave it sit overnight. One forum even stated to try not to disturb it for 48 hours.
As for the gear oil to use, prior to 2015 was 80w90 in the front and 75w140 in the rear. After 2015 because of government CAFE mpg (fuel economy) requirements its been 75w85 in both front and rear. I went with Amsoil 75w140 in both front and rear differentials. Amsoil is well known for putting out premium oil products and since these differentials only hold 2-3 quarts I figured it was a good idea to get the best. There wasnt much of a price difference between the Valvoline gear oil on the Walmart shelf and the mail-order Amsoil. To sum up you absolutely should not put the 75w85 into the differential. If you really want it to last you should go thick and get a premium gear oil. Ive read about different change intervals on the internet. Conventional internet wisdom states to change it at least every 50,000 miles, but some state 30,000 miles. There is a tendency for water or condensation to get into these things and for offroad or oil field work thats something to think about. Take note some members of this forum advised me to go a little thinner on the front differential and that advice was noted, but I decided to go the thicker route. The differential was leaking...had problems with the front differential in the past...lets go thick and dont look back.
To sum up if you are hearing a whirring noise up front and to the left on a Ford or Lincoln truck / suv than carefully examine the front differential for leaks. Its not hard to crawl underneath the front and take a look yourself. Start at that point. Most likely it will be a slow drip drip leak and over the course of lets say 15000 miles about half of the gear oil is left. It takes about 2.5 quarts. You probably wont see it on the pavement or driveway. It will drip out during operation of the vehicle.
My former vehicle was a 2023 Lincoln Navigator L and it developed a whirring noise which turned into a grinding noise. Every time I took it to the Ford dealership I kept getting the run around. One day I took it to an independent mechanic who was extremely helpful and way better than the technicians at the Ford dealership. He showed me the front differential. Fluid was black (out of a new bottle its clear) and there was a glittery silver metal running through it. He told me the front differential was literally eating itself. I took photos and went back to the Ford dealership. The next thing I knew they had my truck for over a month. When I got the truck back there was that noise again. Took the truck back to the dealership and they replaced the left wheel bearing...still there was that noise...took it back and they replaced the the right wheel bearing...still there was that noise. This eventually ended one day when I sold the vehicle to Carvana and got myself a 2025.
I thought all the problems of the 2023 "Covid trucks" were solved in 2025...little did I know that I was wrong. All of a sudden I heard that whirring noise. This time I took it to an independent mechanic to have a look. He told me the front differential was leaking and showed me the entire bottom was wet with gear oil. Furthermore he ended up adding gear oil stating there was only 1 quart of gear oil left in it. After that I drove it around and looked underneath. Sure enough there was a drip. I took it to the Ford dealership and after 1 hour their best technician took me aside, looked me in the eye and told me it was the fill plug...he told me there was not enough sealant on it. The gear oil was passing through the threads.
So I left the Ford dealership and take note I will never go to that one again. Either they were deliberately lying to me or they did not know what they were doing. I went right back to the independent mechanic and decided to take matters into my own hands. I spoke with the independent mechanic and asked if he knew where it was leaking and what he needed to do to fix it. Affirmative! He told me what he needed and that was "Permatex Grey". I enjoy being informed about these matters so I turned to the internet for a crash course on sealant. There is Permatex Ultra Grey and Permatex Optimum Grey. The Optimum Grey is an improved version of the Ultra Grey. I went around to 3 parts stores and finally found a single tube on the shelf of the Optimum Grey. Apparently Optimum Grey is a very popular product around here.
The "fix" the mechanic told me was to take off the metal cover on the differential...there are several bolts...and seal it with the Permatex. He pointed out there is no gasket between the cover and the differential. I looked on the Ford parts website and he was right. Somehow Ford thought it was a good idea to have no seal between the cover and the differential. (see attached image).
Yesterday the entire truck was left at the mechanic at 8am. On the Reddit and Permatex website there were certain ways to use these sealants to perfection. After use you really should not disturb it for at least 6 hours, but preferably 24 to 48 hours. After the work was done I opted to pickup the truck 15 minutes before the mechanic closed for the day allowing it to sit for at least 6 hours. I drove the truck right back to home which wasnt far and its been sitting in my driveway. Im going to try to leave it alone in the driveway until it reaches at least 24 hours from the time of installation. In various forums it was suggested to leave it sit overnight. One forum even stated to try not to disturb it for 48 hours.
As for the gear oil to use, prior to 2015 was 80w90 in the front and 75w140 in the rear. After 2015 because of government CAFE mpg (fuel economy) requirements its been 75w85 in both front and rear. I went with Amsoil 75w140 in both front and rear differentials. Amsoil is well known for putting out premium oil products and since these differentials only hold 2-3 quarts I figured it was a good idea to get the best. There wasnt much of a price difference between the Valvoline gear oil on the Walmart shelf and the mail-order Amsoil. To sum up you absolutely should not put the 75w85 into the differential. If you really want it to last you should go thick and get a premium gear oil. Ive read about different change intervals on the internet. Conventional internet wisdom states to change it at least every 50,000 miles, but some state 30,000 miles. There is a tendency for water or condensation to get into these things and for offroad or oil field work thats something to think about. Take note some members of this forum advised me to go a little thinner on the front differential and that advice was noted, but I decided to go the thicker route. The differential was leaking...had problems with the front differential in the past...lets go thick and dont look back.
To sum up if you are hearing a whirring noise up front and to the left on a Ford or Lincoln truck / suv than carefully examine the front differential for leaks. Its not hard to crawl underneath the front and take a look yourself. Start at that point. Most likely it will be a slow drip drip leak and over the course of lets say 15000 miles about half of the gear oil is left. It takes about 2.5 quarts. You probably wont see it on the pavement or driveway. It will drip out during operation of the vehicle.
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