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-   -   Rear Differential Leak (https://blazerforum.com/forum/steering-suspension-drivetrain-36/rear-differential-leak-107515/)

braden737 Oct 18, 2025 02:59 PM

Rear Differential Leak
 
Rear diff is leaking from both the gasket and the cover itself. Id prefer to be able to replace just the gasket and cover, but these bolts worry me. Thoughts on if it will come out or not
https://cimg5.ibsrv.net/gimg/blazerf...e97725ac1.jpeg

christine_208 Oct 18, 2025 04:04 PM

If the cover us rusted through, I'd say have some replacement bolts on hand with your new cover and gasket. They are all the same so perhaps you can temporarily remove one of the top ones so you can get the right size.

int3414 Oct 18, 2025 04:30 PM

I've seen that before never had a problem getting them out...probably pound a 6 point 1/2" socket on ?

braden737 Oct 18, 2025 06:47 PM

I like the idea of pounding the socket on. My worry is if they will snap and I end up screwed because it then becomes stuck. I don’t want to end up having to replace the whole axle.

christine_208 Oct 18, 2025 09:08 PM


Originally Posted by braden737 (Post 757925)
I like the idea of pounding the socket on. My worry is if they will snap and I end up screwed because it then becomes stuck. I don’t want to end up having to replace the whole axle.

I would think the rear axle is plenty beefy enough to allow you to use an easy-out if necessary. Don't forget, at least the lower ones will likely have oil on thieir thresds from any leak in the gasket and therefore no rust.

braden737 Oct 18, 2025 10:41 PM

That is more comforting… So along with the cover, bolts, and gasket will I also be needing RTV?

christine_208 Oct 18, 2025 11:27 PM


Originally Posted by braden737 (Post 757929)
That is more comforting… So along with the cover, bolts, and gasket will I also be needing RTV?

I've removed my diff cover several times and only use a gasket without any RTV. Others are fans of using only RTV which can work well too. Just be sure to clean the mating surfaces. A razor scraper can work well. Just don't put any deep gouges into the surfaces. If you need to use parts cleaner, be sure to cover the gears to minimize contaminating them. If you get a new cover, a gasket should work well since all the surfaces will be flat on the cover.

Two more things: Before taking the cover off, be sure to clean the exterior of the axle near the cover to minimize dirt falling into the gears. Then be sure you can remove the fill plug. It likely takes a 3/8" square drive and is located on the passenger side above the cast webbing. Be sure to clean it out before inserting the tool into it. I use my 3/8" drive short extension.

braden737 Oct 18, 2025 11:30 PM


Originally Posted by christine_208 (Post 757930)
I've removed my diff cover several times and only use a gasket without any RTV. Others are fans of using only RTV which can work well too. Just be sure to clean the mating surfaces. If you need to use parts cleaner, be sure to cover the gears to minimize contaminating them. If you get a new cover, a gasket should work well since all the surfaces will be flat on the cover.

Two more things: Before taking the cover off, be sure to clean the exterior of the axle near the cover to minimize dirt falling into the gears. Then be sure you can remove the fill plug. It likely takes a 3/8" square drive. Be sure to clean it out before inserting the tool into it. I use my 3/8" drive short extension.

Thankyou Christine

braden737 Nov 7, 2025 04:07 PM

The fill plug is rounded out. What to do now…
https://cimg6.ibsrv.net/gimg/blazerf...90bd65a29.jpeg

christine_208 Nov 7, 2025 06:09 PM


Originally Posted by braden737 (Post 758050)
The fill plug is rounded out. What to do now…
https://cimg6.ibsrv.net/gimg/blazerf...90bd65a29.jpeg

Yikes! I've never had to deal with that. I want yo suggest an easy out but that is pretty big. And besides, you don't want to drill through it and contaminate the inside with metal shavings. I know sometimes people weld nuts to broken studs. I've never done that.

Might a custom made socket work after cleaning up the head with a Dremel?


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