cant stop rear diff leak

[DoubleWasp]

Read the instructions carefully for Gear Oil RTV. You are supposed to wait an hour before giving final torque. It fully cures in 24 hours. I never wait that long before putting gear oil in, but you definitely don't want to do it immediately.

The type of gear oil you are using matters too. Royal purple and a few other oil makers forbid the use of gasket makers or seals besides Gear Oil RTV because the friction modifiers break down silicone based RTV.

You can do a gasket if you want, but gaskets do not do much to halt the encroachment of corrosion from the difference cover lip inward. I no longer use gaskets on Diffs for this reason.

 

[Trav]

Originally Posted By: Robenstein
Originally Posted By: Trav
Originally Posted By: Robenstein
As mentioned, make sure your cover is as flat as possible to avoid mating issues. I have seen more leaks caused by wavy stamped steel covers (timing, valve, diff) than anything else.

The indian head shellac is old school, but works. I think the Right Stuff is a bit more forgiving personally.



You should never use RTV with a gasket, it is 100% not necessary and can actually cause a leak. Shellac and high tack are made to work with the gasket not create 2 separate additional seals. RTV alone is fine. This guy is using high tack to hold the gasket which is fine but it and shellac permeate the gasket somewhat and helps prevent gasket porosity.
i tighten them slightly more than snug never 30 ft lb, maybe 10.




I didn't say to use RTV on the gasket. I said that using The Rights Stuff is simply more forgiving than using the shellac method which is applied to a gasket.


No but that's what he did, sorry for the misunderstanding. Why would you use RTV instead of a gasket if one is available, rtv is not new tech its cheap production line tech and in most cases inferior.

 

[Robenstein]

In some cases it is better than gaskets IMHO. I always use it when putting intakes (especially on aftermarket ones) on small block chevys. The gaskets on the front and rear are known leakers.

 

[mobilaltima]

I always use gaskets, I hate RTV, just in this situation I didn't know what else to do. 30 ft lbs seems to be the GM spec, Ive used it with no problems. AAM calls for 23-33 ft lbs. i recently changed the fluid on my buddies 2011 Chevy with the 10 bolt rear end, reused the gasket, and torqued it to 30 and hasnt leaked a drop since.

 

[demarpaint]

I have better luck with gaskets and Hi Tack adhesive.

 

[barkingspider]

I've done many GM truck diff fluid changes. I have used gaskets without issues. I have also used gaskets with a very thin layer of rtv on a chrome cover and it did not leak. If the felpro doesn't work, then the issue maybe something other than the gasket or rtv

 

[wtd]

I used a lube locker gasket on the rear diff of my 14 Mustang GT when I installed a Ford finned aluminum diff cover. I don't like RTV or gasket maker and would rather use a gasket if one is available. I used Gaskets on both of my 98 Chevy trucks and on my 1970 Monte Carlo. I have not had any rear diff leaks on any of these vehicles.

Wayne

 

[Lubener]

Originally Posted By: Chris142
Make sure there are no dimples where the bolts go through the cover. Straighten as necessary. clean the cover and housing down to bare metal. Cant have any oil on either. clean the cover with brackcleaner and put a bead of silicone on the cover and around the bolt holes.

Clean the housing with the brackcleaner and immediately install the cover with out a gasket, Just your sealer. Let it set an hr then fill it up. The OEM's got away from gaskets a long time ago.


Sounds good. The cover is like your transmission pan, check for flatness of the diff. cover. Use a ball peen hammer to gently straighten as needed.

 

[Trav]

Originally Posted By: Chris142
The OEM's got away from gaskets a long time ago.


That may be so but it doesn't make it better, it is simply more cost effective for a robot to apply the stuff out of automated machines. When the machine applies the stuff the housing is new and spotlessly clean and its on its back, all the conditions you cant duplicate with the diff in the vehicle.

 

[another Todd]

Make sure it is actually a mating surface leak, and not something that is cracked and leaking.

 

[mobilaltima]

Well, I traced down the leak to the drain plug on the rear diff, so instead of just messing with a 15 year old drain plug and gasket, I got a new updated one from the dealer. My only concern is, while the old plug sat flush in the housing, this new updated plug sticks out a little, it looks and sticks out just like the drain plug on a Cummins. i torqued it to the proper spec, 24 ft lbs, and I let the truck sit overnight and I'll check it this afternoon for leaks. any cause for concern on the new plug?