Hello all, 99 2WD 4.6L

I have had this issue for some time now.

If i am at a complete stop (stop sign or traffic light) and i accelerate turning right or left, there is a humming or grinding type noise with some vibration, from the rear end, almost like something is sticking. Once i make the turn and start to accelerate, the noise and vibration disappears.

If i take off from a complete stop without turning and travel straight, there is no noise or vibration.

I noticed this week some oil stains on the driveway at the rear end.
What is the most common problem for leaks in the rear differential?
Just a new gasket?

What does everyone recommend as a fluid replacement? 99 2WD 4.6L

Does this make any sense?
"For the rear you need 75w-140 full synth, and also 4 oz of MC XL-3 supplement (rear Traction Lok)"

Thanks everyone

 

if you open it up to change the gasket make sure to check for random pieces of metal and stuff like that. My buddies rear dif was making noise beyond belief this summer and when we opened it up we found a tooth from the pinion was completely sheared off! but of course this was after dragging on a stock (i mean nothing but oil changed if even that) 4.2 w/ 250k+ miles. Needless to say I dont go to him for advice on how to upkeep my truck. I strongly doubt you'll find a large chuck of metal but ya never know!

Good luck

 

Thanks, do you guys use an actual gasket, or just some oil resistant gasket maker?

how many ounces of traction lok would you guys add? i know minimum is 4oz, but some like to add more.

Thanks

 

$10.99 for a FelPro gasket at NAPA. Just did mine 3 days ago. Spend the money and do it right. You'll need to find out what rear you have... 10 or 12 bolts, 8.8" or 9.75"... It should all be on two tags hooked to the differential cover, mine even showed the reccomended fluid.

Spend a few extra minutes to clean up the two mating surfaces. If it's leaking fluid out, that means there's a way for salt and water to get in. You'll probably find some rust where the cover mates.

The fluid you mentioned is right. Look for full synthetic, not a blend. You'll probably need 2.6 liters of it. Just to warn you, it's expensive fluid... $15-$20 per liter (another reason to get the gasket and minimize your chance of doing this again). For the additive, you don't need it unless you have limited slip (Trac-Lok). The bottle says specifically "do not overtreat". Not sure what happens if you do, but I wouldn't want to find out.

 

Use one bottle of modifier, if the chatter is still there after a couple of weeks you can add one more.

 

Its not really a noise issue but more a vibration like something is slipping

 

Is one bottle usually 4 oz?

Also i know you guys in the US have alot more variety to products than we do here in Canada. Is there anyone that knows of what modifier is the best to use? We have an "Amsoil Slip Lok" here and Quaker state 75 140 synthetic.

 

Lots of guys say not to use a gasket just some rtv oil resistant liquid gasket?
I was thinking of using an actual gasket with a thin bead of liquid gasket all the way around

 

That's what I'd do.

 

You can use just RTV if you want, but it leaves more room for error and will most likely fail sooner. Do it nice or do it twice. Spend $10 and do it the best way you can. RTV on the gasket works to. I've seen that a lot.

My friction modifier/additive came in a 7 oz bottle. All three stores I went to only had one kind. I guesstimated half of it to get about 4 oz.

 

I have a 97 F150 XLT 4X4. It did the same thing.

Turns out the pinion was loose, the carrier needed replaced(teeth missing), 1 axel shaft was damaged.

So all of the bearing and seals also got replaced. Not to scare you but it could be something big. It cost $3000.00 to fix mine.

I also just bought this truck 4 months ago. Should have checked it out better.

 

my rear end (97 4x4) also says to use 75w-140 full synthetic....... but...... my book says for 'ford conventional and traction-lok axels' to use 80w90. why the discrepency?

 

Your book is old. They have changed the recommendation. Same thing with the engine oil, the current recommendation is 5w20.

I'm not saying that you can't use something else, but the RIGHT modifier to use is Motorcraft, and that comes in a 4 oz bottle. Some diff oils allegedly come with the modifier already in it too.

 

does anyone know the torque specs on the bolts?

 

I have 10 bolts, does that mean i need the 8.8" gasket? also my bolts are badly rusted and falling apart, as well as the cover. I know the cover is replaceable, where would i get the bolts from?