Rear End Differential Oil Leakage.
03-19-2009, 09:12 PM
#11
Almost any "how to" you will read on here or other forums will tell you to fill the diff until fluid comes out of the fill hole, but this is incorrect. The fluid level should be roughly 1/2" to 1.5" below the fill hole (15-45mm). I measured mine with a paper clip I had bent. If you are going to retain your G80 you will need to use synthetic 75w90 gear oil. My rear took right at 2.18 qt (I'm **** and measured ) and was roughly 1/2" below the fill hole.
03-19-2009, 09:27 PM
#12
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Almost any "how to" you will read on here or other forums will tell you to fill the diff until fluid comes out of the fill hole, but this is incorrect. The fluid level should be roughly 1/2" to 1.5" below the fill hole (15-45mm). I measured mine with a paper clip I had bent. If you are going to retain your G80 you will need to use synthetic 75w90 gear oil. My rear took right at 2.18 qt (I'm **** and measured ) and was roughly 1/2" below the fill hole.
03-19-2009, 09:36 PM
#13
Well, your diff should have a little blue tag on it, at least mine does. It says to fill with 75w90 synthetic and tells you how much to fill (15-45mm below fill hole). Maybe only G80 equipped rear ends had that tag.
Removal Procedure
1. Raise and support the vehicle. Refer to Vehicle Lifting.
2. Drain the rear axle. Refer to Lubricant Change.
3. Remove the rear cover bolts (1).
4. Remove the rear cover (2) from the housing.
4.1. Catch the oil in a drain pan.
4.2. Remove any gasket material.
Installation Procedure
1. Install the rear cover (2) and a new gasket. Notice: Refer to Fastener Notice in Service Precautions.
2. Install the rear cover bolts (1). Tighten the bolts in a crosswise pattern to 40 Nm (30 ft. lbs.).
3. Fill the rear axle to the following levels. Refer to Fluid and Lubricant Recommendations.
o 8.6 inch ring gear rear axles15 - 40 mm (0.6 - 1.6 inch) below the fill plug.
o 9.5 and 10.5 inch ring gear rear axles 0-10 mm (0.4 inch) below the fill plug.
4. Remove the supports and lower the vehicle.
Removal Procedure
1. Raise and support the vehicle. Refer to Vehicle Lifting.
2. Drain the rear axle. Refer to Lubricant Change.
3. Remove the rear cover bolts (1).
4. Remove the rear cover (2) from the housing.
4.1. Catch the oil in a drain pan.
4.2. Remove any gasket material.
Installation Procedure
1. Install the rear cover (2) and a new gasket. Notice: Refer to Fastener Notice in Service Precautions.
2. Install the rear cover bolts (1). Tighten the bolts in a crosswise pattern to 40 Nm (30 ft. lbs.).
3. Fill the rear axle to the following levels. Refer to Fluid and Lubricant Recommendations.
o 8.6 inch ring gear rear axles15 - 40 mm (0.6 - 1.6 inch) below the fill plug.
o 9.5 and 10.5 inch ring gear rear axles 0-10 mm (0.4 inch) below the fill plug.
4. Remove the supports and lower the vehicle.
03-22-2009, 03:42 PM
#16
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I have to agree with everyone who has posted above, but since this is "performancetrucks.net" I am surprised that nobody recommended you fill your diff with Royal Purple. I believe Royal Purple puts more zinc in their products to reduce friction. They do have documented increases in performance on their website.
03-28-2009, 06:29 AM
#17
Almost any "how to" you will read on here or other forums will tell you to fill the diff until fluid comes out of the fill hole, but this is incorrect. The fluid level should be roughly 1/2" to 1.5" below the fill hole (15-45mm). I measured mine with a paper clip I had bent. If you are going to retain your G80 you will need to use synthetic 75w90 gear oil. My rear took right at 2.18 qt (I'm **** and measured ) and was roughly 1/2" below the fill hole.
Use a gasket!!! if the RTV Gets in the case it will cause damage to the G-80. A tube of Grey RTV is around $6.00 a gasket cost nearly the same... I see more leaks with RTV then any thing... Your choice though... Make sure you suck up any fluid so it doesnt run out while your trying to seal the cover. Also wipe the ouside edge of the gears off including the teeth area only were it's exposed so It doesn't leak down on the sealing surface. If it does you will have a leak for sure... my Dad took his Suburban in 3 times and they kept resealing it with RTV. I told him "Take it back and tell the guy to use a gasket like they did from the factory. If I have to go down there I am going to ruin his day in front of all of his customers while I am there. It didn't leak before and it shouldn't leak afterwards if was done properly. The guy finally used a gasket and what do you know... no more leak... The mechanic told my Dad That he told his boss from the beging to use a gasket but his boss didn't want to spend the money. Retail from GM is around $10 Retail at some parts stores is around $8-$9 for a fel-pro. With a discount, The average shop gets it for about $6-$7 Hell, I started buying them at the swap meet for like $2-$3 In the Original Gm packageing when I can find them...Grey RTV makes a better seal on an application like this rather then Black or Red because the grey hardens up. It's what they use to seal oil pans from the factory on a lot of newer cars when they don't use a Gasket...
03-28-2009, 09:31 AM
#19
I prefer to use a gasket myself, but when done properly, RTV will work just fine, it's just a little more tricky. The sealing surface must be completely clean and dry, or the RTV will not adhere. You must make sure that the gear oil has stopped running out of the diff or you will definitely have a problem. As for gasket choice, spend the extra $2 and get the GM gasket. The aftermarket gasket that came with my TA rear diff cover quickly blew out in the "corners" by the oil passages to the carrier bearings, creating a fairly rapid leak. I replaced it with the proper GM gasket and have been leak free ever since. 
03-28-2009, 05:55 PM
#20
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i used the one that came with my TA cover.. and i see a little oil leaking.. i think its coming from the drain bolts on the cover... either way it sucks.. gotta go get more LSD fluid.....
i was always told to use RTV and the gasket... haha.. maybe thats why mines leaking...
i was always told to use RTV and the gasket... haha.. maybe thats why mines leaking...