my truck is a 2000 f150 scab 5.4 and when i am backing up in reverse i hear this whine sounds like it is coming from the drivers side front but idk plus i have been feeling a vibration in the rear at about 30mph but goes away when i accelerate heavy Any ideas?

 

Have you checked your universal joints?

 

Sounds like the rear diff fluid might be breaking down..? If so, after you change it with the RIGHT fluid, the problem may just disappear or take up to 75 miles or so to completely go away. If you haven't done that yet to your 2000 model - It's prolly due anyway.

 

Whats the right fluid to put in it? 75 140 right? Any specific brand?

 

Yea - SAE 75W - 140 GL-5 Synthetic gear lube for the rear. OR equivalent

4 ounces of "Friction Modifier" for the 8.8 & 9.75 rear gears. Don't forget the modifier !!

Both can be found at most third party auto suppliers - It doesn't have to be "Motorcraft" Fluid. If you want that , you'll probably have to make a trip to the dealership. Modifier Part # = C8AZ-198546-A @ the dealer.

I used Mobil 1 and TransX Modifier (I think it was) last time, The Mobil 1 was $12 a bottle and took 3 or 4 bottles to fill - Yea the stuff isn't cheap.

You'll need RTV Black Permatex for the rear cover gasket. Or purchase a gasket from somewhere if you choose to use one - What ever your comfortable with, I never use a gasket on the cover personally .

 

Yea, i was looking at using the mobil 1, but its $17/qt here in Ca. What is on the cover that ford put on? A gasket? RTV black never leaked for you?

 

- I know, that stuffs not cheap..I believe there was a gasket, yea a thin black gasket the first time I did it.

No, that RTV won't leak , I've always used Permatex myself. I used the High Heat Black back there, that's what I usually have on hand. Gr8 stuff - 270,000 miles on that rear end and it's never leaked.

A gasket will work just the same and I would probably use one if I had one handy. - It's not as messy and takes less time .


Yea , they show a gasket , #3 below -