I changed the rear diff cover gasket in our Tahoe today because it was leaking badly. It was an act of congress to get the 10 bolts off thanks to 12 years of rust. I got the bolts off, wire wheeled each one of them, then wire wheeled the cover. I scraped off the old gasket from the rear diff and used brake cleaner to get everything spic and span. I coated the bolts with PB Blaster before reinstalling so they'd torque down correctly. I RTVed both sides of the gasket and set it in place, then finger tighetened each bolt. I torqued all the bolts down to 165 inch lbs. (13.75 ft. lbs.). Topped it off 2.5 quarts of 80w90. Drove it around for about 60 miles today and the dammn leak is back.

Do I have to start all over again to correct this? Such a simple thing has turned into a debacle. If I go at it again, what do I need to do to ensure that it seals correctly? I guarantee everything was CLEAN. Cleanliness was not the issue. You could eat off each mating surface. Was my torque value too low?

I've done this job on four other cars/trucks and never had this issue.

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2012 Ford Fusion SEL, 2012 Chrysler Town & Country, 2007 Chevy Silverado LT, 1999 Pontiac Firehawk, 1979 Pontiac Trans Am

Make sure that both mating surfaces are flat and smooth. If there's rust pits or the bolts were over-tightened, the flange on the cover could be bent. Then you'd have to find one from a JY.

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Bye Bye:

RIP sandrock

You could also tighten the bolts a little more. There might have been a little resistance from the threads and therefore the bolts may not be applying the correct pressure to the cover. I had to do the same thing to my suburban. I checked the cover and everything was clean and flat and leaked until I put a 1/4 turn on each bolt. I think after the rtv set up, it acts as a rubber gasket once it is tetightened.

i would guess tighten up the bolts. I changed the oil in my diff (it wasn't leaking I just figured it could use it) and I just put the bolts back on tight and no problem in fact now that I am thinking about it I may not have used a gasket I think i just rtv'd the thing

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2000 ssei gone but not forgotten

Current fleet:
2009 G8 v6, 2009 Avalanche LTZ, 2013 Volt

Sounds like it was done right. Clean, gasket, install. Like the oil pan, the stamped flange on the cover needs to be perfectly flat.

Are you sure the leak is coming from the cover? Any kind of leak on the diff case will end up dripping off the cover (front seal, crack in the cast iron case, etc.) Another thing to check is the breather on the top of the diff case. If it gets plugged up, the pressure inside the case will force the oil out past the seals when it heats up.

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Bye Bye 1990 Bonneville LE... Now it belongs to my daughter
In the Garage: 2009 Subaru Outback, 1987 Camaro, 2006 SV650S, 1995 Regal 182 "ASANAGI", 1962 Ford Galaxie 500, 1995 Ford F150 XL 4WD, 1953 Farmall Cub

Dont use a gasket, get some black RTV 732 silicone, works everytime, we use it at work on all diffs we build. We do a few a week.

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2016 Dodge Charger Scat Pack 392
3.09's 8 Speed Auto
04 GTP

My experience with solid axles, well any gasket for that matter is to use RTV or a gasket, never both, the RTV doesnt let the gasket seal. If you use RTV make sure you give it time to set up. If I have a gasket I only use a lil thin bit of RTV in a couple spots just to hold the gasket in place while I get the bolts in the piece im bolting down.

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Are you sure the leak is coming from the cover?
Could it be coming from the pinion seal?

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2000 SSEi - SilverBullet - 78,000 kms, 4" "straight shot" custom headlight ram air inlet, TOGs, 1.9's, Lsd, 2.9-3.4"MPS 10-15 psi, Ported GenV, EGR eliminated, OR pushrods, oil volume kit, trani cooler & shift kit, Titanium retainers, 90 lb springs, 160 Stat, 42# injectors, Fuel pump voltage increase, Wideband O2, 3" to dual 2 1/2" Magnaflows, Snow Meth/water injection, after SC temp gauge, 255/50WR17, timing commander set 15-18*@WOT, 2 speed Fan over-ride, disabled DRL, Solid motor mount, Meziere Electric water pump, adjustable fuel pressure regulator, Drilled & slotted rotors/ceramics, GXP sway bars and STB, Upgraded and rebuilt transmission with ZZP 2500 rpm stall TC, Pioneer Bluetooth stereo with sub and 800 W amps, PB 13.5 quarter, (April 2014 car of the month)

Sorry to be so late back into this thread.

Right after I posted this I went back into the garage and tightened the bolts. I took them down to 205 inch lbs. I figured it couldn't hurt since it was already leaking. I also rewiped everything down to be able to start fresh on where the leak was coming from. That was Saturday night...

Sunday AM I checked it before we headed out to breakfast and it was bone dry. No drips on the ground, nor anything on the under side of the diff. We then drove it about eight miles...when we got out I inspected it and the bottom of the pan was wet. Ironically, though, there was a wide streak of fluid coming down from about an inch and a half from the top of the cover. Almost like there's a pin hole or something in the cover, right behind the vertical gear in the diff. This coincides with the fact that it will only leak when being driven. The top of the axle is also dry.

The other interesting point was when I cleaned the over, the rust was coming off in sheets. I'm thinking the metal just has so much corossion that there is at least one pin hole leak.

The next best bet will be to pick up a new cover and give it a shot again. I've never heard of not using RTV with a paper-gasket, but am open to suggestions! My father-in-law suggested using "High Tack" instead of RTV.

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2012 Ford Fusion SEL, 2012 Chrysler Town & Country, 2007 Chevy Silverado LT, 1999 Pontiac Firehawk, 1979 Pontiac Trans Am

Dont use the Paper gasket at all. Just RTV. Hi-tak will help hold the gasket in place if you decide to go that route. Rust like that is very common, pin holes certainly are not. Hard to say though. I can probably get you the cover for cheap if u want.

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2016 Dodge Charger Scat Pack 392
3.09's 8 Speed Auto
04 GTP

Oops...forgot to update this..

I ended up buying a new diff cover and gasket. I swapped it out Tuesday night. I didn't use any RTV and just the dry gasket which was supplied with the diff cover. Everything was good for three or for days, now I have a very small drip again. I think it's my own fault - I only tightened the bolts down to 15 ft. lbs. I'm reading that I should have gone to 32 ft. lbs. I just haven't had the time to get back under there and retorque everything.

The major leak is now gone. It had to have been that old diff cover.

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2012 Ford Fusion SEL, 2012 Chrysler Town & Country, 2007 Chevy Silverado LT, 1999 Pontiac Firehawk, 1979 Pontiac Trans Am

Ive always just used an air ratchet and cranked em down, never had any problems.

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loose the gasket, use RTV

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2016 Dodge Charger Scat Pack 392
3.09's 8 Speed Auto
04 GTP

All this banter about leaking diff covers made me inspect my front axle cover on the Jeep and ....... drips!

So I remove the level plug to check and it's down almost a full liter (quart)!

Topped it off but it's still dripping about a drip every couple of hours.

It should take a year or so to lose significant oil, so the cover reseal will have to wait.

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2000 SSEi - SilverBullet - 78,000 kms, 4" "straight shot" custom headlight ram air inlet, TOGs, 1.9's, Lsd, 2.9-3.4"MPS 10-15 psi, Ported GenV, EGR eliminated, OR pushrods, oil volume kit, trani cooler & shift kit, Titanium retainers, 90 lb springs, 160 Stat, 42# injectors, Fuel pump voltage increase, Wideband O2, 3" to dual 2 1/2" Magnaflows, Snow Meth/water injection, after SC temp gauge, 255/50WR17, timing commander set 15-18*@WOT, 2 speed Fan over-ride, disabled DRL, Solid motor mount, Meziere Electric water pump, adjustable fuel pressure regulator, Drilled & slotted rotors/ceramics, GXP sway bars and STB, Upgraded and rebuilt transmission with ZZP 2500 rpm stall TC, Pioneer Bluetooth stereo with sub and 800 W amps, PB 13.5 quarter, (April 2014 car of the month)

Great, now you guys have cursed me. I have to change differential fluid on our truck soon, and now the dang thing is going to leak, isn't it?!

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Bye Bye:

RIP sandrock

Not of you do it right...

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Yeah, i was being sarcastic, lol.

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Bye Bye:

RIP sandrock

I retorqued it to 30 ft. lbs. and it seems to be better, but I'm still getting a little oozing. We put 500 miles on it this weekend and it's moist on the bottom. The next time I tackle this I'm only using RTV. I should have listened the first time...

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2012 Ford Fusion SEL, 2012 Chrysler Town & Country, 2007 Chevy Silverado LT, 1999 Pontiac Firehawk, 1979 Pontiac Trans Am

If you seal it with silicone, use High Temp Silicone Grey.. Also fill with quality( synthetic ) gear lube.... If you have an LSD make sure its compatible with a Limited Slip

i used the lucas gear oil when i did mine. it's just an open diff however they bottle said it can be used in LSD's without an additive

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2000 ssei gone but not forgotten

Current fleet:
2009 G8 v6, 2009 Avalanche LTZ, 2013 Volt