Hi everybody,

I just did my oil today and noticed some problems with my front and rear differential fluid. In the front, there is water, indicated by the milky looking fluid coming out when i opened it up. In the rear, the fluid came out really dark and on the magnetic plug tip there was lots of shrapnel. I did not have these problems the last time i did my oil, which was about 5500km ago. I have only had the truck since October, it only has 17,500km on it and i only use full synthetic oil. Any idea what could be causing this? Leaky diff seals? Condensation? I dont drive through ponds or anything. I have an appointment to take it into Ford on monday but i wanted to see if i could get an idea what might be causing these problems before i went. The help is greatly appreciated.

Justin

 

The water in the diff may be caused by a leaky seal, but if you didn't notice any oil on the ground or any leaking out on the housing then I'd suspect thats not the problem. My guess would be the breather is stuck open and is allowing water to backflow into the housing. Have the dealership check the breather valve. In the rear axle was it chunks of metal or metal shavings? Metal shavings are normal from gears meshing, but chunks are not. Given that you said the gear oil was not very old and came out dark and had what sounds like chunks you probably have a bearing going out. When a pinion or carrier bearing goes out it creates alot of heat which overheats the oil breaking it down and turning it black. The chunks may be pieces of bearings coming apart. A good dealership should be able to diagnose that pretty easily by checking for ease of motion, excessive noise, and any play in the gearset. Make sure they check it out since you just changed the oil some dealerships may try to weasel out of it and say everything is fine. If you can watch them pull the covers and check everything out. They are less likely to skip looking things over with the customer standing right there.

 

The owners manual for my 2000 F150 says the rear diff is lubed for life. However, I dumped mine and refilled with synthetic trying to get rid of traction lok chatter. It didn't help. Then, when I did my rear brakes, I saw that the right rear axle seal was leaking. So. I had to dump the lube again to remove the rear axle to get at the seal. This last time, I used two 4 oz. bottles of friction modifier and I am getting very little chatter now.

 

NEVER believe a manufacturer when they say areas, especially like that, are lubed for life. Keep in mind Ford's lubed for life concept of the steering idler arm and pitman arm. We all know how well that has worked in the past. Unless Ford has managed to make an oil that will not break down over time under the heat of gears constantly meshing. Somehow that seems highly unlikely. Any oil no matter who makes it or what kind breaks down over time with heat. They may be able to extend the life by using synthetics (Ford uses 75W140 synth after 97 already), but thats about all they can do. Not flaming or arguing with you, just pointing out that even though the owners manual states something like that I wouldn't believe it for a second. I can't believe that Ford actually thinks something like that can be lubed for life

 

Most people don't ever change the diff fluid anyway. The older cars had removable center sections and you had to remove the center section to drain the fluid.
The manual also says that if you have severe service, the front diff which has regular lube should be changed every 3000 miles unless you also put synthetic in it too. My 20004x4 front diff has a drain plug and the rear diff does not. I have to remove the rear cover which isn't too bad. I just have to buy $50 worth of synthetic lube and keep the silicon seal gasket maker for the gasket.

 

I just got back from my ford dealer and this is what i discovered.

a) Ford uses a silicone based lubricant in the front differential that looks deceptively like watery emulsifate when you drain it. I had no water in my front differential.

b) Ford does not use this same lubricant in the rear differential. They use a darker one. The metal i was making was supposedly normal and the wear pattern on all the bearings and gears was normal for a f150 like mine.

However, they were "nice" enough to change my front and rear diff fluids anyway even though i just asked them to tell me if i had a problem and correct it if there was one. The tech also mentioned that my fluids looked very good beforehand, so why they decided i needed a change is beyond me. Ford recommends differential fluid changes only every 100,000km but i guess i got mine done at 18,000. So now that i'm $220 lighter....

 

$220 worth of education!

 

My construction company does a fair bit of business with this ford dealership. I think they will make it better.

But yes, $220 worth of education