Fixing rear differential leak
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Joined: May 2022
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From: Roanoke
Fixing rear differential leak
Do you think the leak is coming from a bad seal on the front of it or somewhere else, should I just take it to a shop, I’m admittedly a novice when it comes to car issues
My rear diff has a slow leak and I think the gasket just needs to be replaced, it’s the 4.10 8.8” limited slip ( axle code R7) what oil should I use? Also is this an easy enough task a novice can do?
Last edited by Rzc; May 17, 2022 at 08:51 AM. Reason: Update
Welcome to the forum
There probably is no gasket if the cover has not been off before, factory just used black RTV
But you can buy a gasket for it which is not a bad idea
One of the axle tubes will have a VENT and hose on the top side, make sure its clean and unblocked, there should be a small filter at the end of the hose under the bed
Insects like to block this vent hose, and that causes LEAKS
Axle and fluid heats up when driving, when you heat up any fluid it expands, the vent is there to equalize pressure inside the axle housing, if vent is blocked then internal pressure will be forced out at the bearing/ale seals, pinion seal and the differential cover, where ever it finds the easiest path out
75w-140 is the synthetic version that is used now: XY-75W140-QL
But you can reuse what it came with which is XY-80W90-QL, regular oil
5 pints is spec, 2.5 quarts
Because its a Limited Slip differential you also need to add 4 ounces of the Friction modifier, XL-3
Add this first then refill
Or you can buy the synthetic or regular oil with the Friction modifier already mixed in, in the correct proportions
There probably is no gasket if the cover has not been off before, factory just used black RTV
But you can buy a gasket for it which is not a bad idea
One of the axle tubes will have a VENT and hose on the top side, make sure its clean and unblocked, there should be a small filter at the end of the hose under the bed
Insects like to block this vent hose, and that causes LEAKS
Axle and fluid heats up when driving, when you heat up any fluid it expands, the vent is there to equalize pressure inside the axle housing, if vent is blocked then internal pressure will be forced out at the bearing/ale seals, pinion seal and the differential cover, where ever it finds the easiest path out
75w-140 is the synthetic version that is used now: XY-75W140-QL
But you can reuse what it came with which is XY-80W90-QL, regular oil
5 pints is spec, 2.5 quarts
Because its a Limited Slip differential you also need to add 4 ounces of the Friction modifier, XL-3
Add this first then refill
Or you can buy the synthetic or regular oil with the Friction modifier already mixed in, in the correct proportions
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Joined: Mar 2020
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From: US
What I use to change my 2001 8.8" 4.10 LimitedSlip RearDiff, AxleCode D2, every 33kMiles:
~ Cover = 10Bolt wOut Drain
~ FillPlug = 0i500oDia*14mNPThrd*0i375Long*0i375FemaleSquareDri ve
~ PermaTex OilResitant Black RTV for CoverGasket
~ FricModifier = 4.000oz 0.125qt 0.118Lt Required For LimitedSlip, Ford# c8az-19b546-a, Swapped To AmsOil# SlipLock
~ RearGearLube = 57.60oz 1.800qt 1.703Lt Ford# 75w140.FullSyn Or Equal, Half+Half Mixed With AmsOil# SAE250.FullSyn
Hope this helps.
~ Cover = 10Bolt wOut Drain
~ FillPlug = 0i500oDia*14mNPThrd*0i375Long*0i375FemaleSquareDri ve
~ PermaTex OilResitant Black RTV for CoverGasket
~ FricModifier = 4.000oz 0.125qt 0.118Lt Required For LimitedSlip, Ford# c8az-19b546-a, Swapped To AmsOil# SlipLock
~ RearGearLube = 57.60oz 1.800qt 1.703Lt Ford# 75w140.FullSyn Or Equal, Half+Half Mixed With AmsOil# SAE250.FullSyn
Hope this helps.
