The rear differential on my 1997 4Runner is rusted and leaking. The leak isn't from the cover but from pin point size rust holes. The undercarriage is very rusted and the ability to change-out the rear assembly without complications is questionable. I can't do the work myself and I'm having trouble finding someone willing to take on the repair. I'd like to hear from anyone with experience sealing a housing leak using JB Weld, Permatex, Flex Seal, etc.l I watched a YouTube video of a guy who used several coats of Flex Seal Spray to cover the diff casing and it appeared to seal the leaks. However in the comments someone mentioned that the differential oil could break-down the Flex Seal. Permatex makes a product which isn't damaged by oil. I don't drive the vehicle very often, not very far from home and not hard core off road, so I just want to get it back on the in operation. It is great in the snow and to haul stuff that doesn't fit in my car. I don't want to get rid of my baby, I bought it new in Nov. of 1997, and hope someone here will offer a solution. Comments on options appreciated. Thanks!

 

Nothing is going to stick to a dirty oily surface. The cheapest way would probably be to identify the actual leaks, drain the diff, clean/sand just those spots and dab on JBWeld. You could follow that by using a rust remover on the entire housing and then painting or sealing it.

 

I 2nd jb weld.

Or get the dorman cover and replace the whole thing. Or find a better shape housing to swap in.

https://www.dormanproducts.com/p-105095-926-993.aspx

 

JB it. I use an epoxy putty called "LACO" from industrial supply places. I've used it in industry during my career as well as to fix drippy oil pans and gas tanks. Good stuff, cheap and machinable.

 

Thanks for responding and agreeing it is a possibility to patch the old housing. I can handle the expense of replacing the rear-end but I'm concerned about other rusted parts will have to be detached and reattached the whole thing so I'd rather try to patch first. The frame is rusted but doesn't have holes so I feel OK driving it but only for local driving. When I do have it patched, I'll post and share how it worked out.

 

Dear WVRunner. Same has happened to our 97 4 runner regarding rear differential oil leaking out of rusty differential and housing. Have you had any luck repairing yours? Toyota quoted 8,000 dollars to replace the entire housing and all the other parts that would be broken and needing replacement when they take off the differential. Thank you!! Our 4 -runner only has 120,000 miles and is otherwise in great shape (besides underneath rust). It is difficult to just get $800 for it from cash for clunkers!