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2002 tundra differential rust

2002 tundra was recalled for frame replacement due to excessive rust. Rusting is well beyond frame alone: steering rack, all suspension components, axles, etc. L/S Differential is now leaking due to rust (crazy for a truck this age, especially with very limited off-road use) . Trying to get Toyota to cover it, but so far NO luck even with main office escalation. What is best option to stop and seal leak short of axle replacement? I’ve read about expoxy and POR-15 treatment, but would need to keep oil off surface to do so. Is this a matter of draining, flushing from inside out to de-grease the leak path and all surfaces to be plugged/patched?..then refill with oil, hope for no leaks?

Please show us pictures, so that we can advise

Where, exactly, is the leak? But yes, drain it, clean it (with acetone or MEK) epoxy it, refill it and start looking for another truck…Write your state DOT a letter and ask them to please put more salt on the roads…And YEAH, that Calcium Chloride liquid they spray on everything, that’s great stuff for dissolving metal…

have not located leak exact location of leak, but you can see where oily area is. I will clean and remove rust to get better idea of where leak is to be fixed.

leak appears to be at bottom of rounded portion of differential, on side shown in picture, off center a bit, approx below the fill plug. Checked vent and it is clear…this is a gravity leak

Here are a couple of shots of my 1990 Toyota P/U…We call her “Rusty”. It spent the first 17 years of it’s life on Cape Cod…The body is badly rusted but not the chassis…Strange…

Do you launch a boat with the vehicle? Oceangoing, or fresh water?

I’m used to the ford rear end so I’m not sure how the cover unbolts on that, but I would definitely drain it, clean it off, load both mating surfaces with the right permatex for the job, let it sit a little and get tacky, then bolt it back up, and fill it up. After that I suppose you could periodically check the level by removing the drain plug and dipping your finger in. Top it off until it drains out a little and plug it back up. Good luck


The cover doesn’t unbolt on that rear end

Rather, you remove the entire 3rd member, from the front side . . . after removing the axleshafts

Get some of that "Rustolium Rust converter.
Slap it on and you’ll have two trucks???

That is pretty Rsuty though

+1 Caddyman. It looks like when you chip the rust off, the oil will drain itself so have a pan handy. The problem, as you’ve surmised, is to keep oil off the patch area as it will ruin the adhesion. I fixed a rust-through in a gas tank the following way: Scrape and sand down to metal around the hole so there’s clean metal an inch or so in all directions. Cut two cloth patches a little smaller than the sanded area (I used denim from old jeans). Have your epoxy ready to mix, then do a final wipe and slap a piece of tape on the hole just barely big enough to stop the dripping. Then do a final cleaning with solvent, dry and put a coat of epoxy over the entire area of sanded metal and tape and push a cloth patch into the epoxy. When mostly set, mix a new batch of epoxy, cover the area and push the second cloth patch into it. When mostly set, cover with a final coat of epoxy. (If it ends up a hole bigger than, say, 3/8", go ahead and put another cloth/epoxy layer on it.) This type patch held on my gas tank for the two years before I sold the vehicle. I used clear type epoxy; I’m not a fan of JB Weld.

@db4690 yikes!
@insightful talk about a Mcgiver (spelling?) job

To the OP if you plan on keeping the truck and all else fails, you might look into finding a used rear end, have it freshened up and bolted in

Caddyman, your '90 Toyota is exactly the same color and cab and drivetrain configuration as my '89 was, assuming you have the 4-banger. The only engine difference would be that mine was carbed and yours is TBI. Ah, sweet memories.

I live in Minnesota, and I’ve never seen a diff that rusted out.

What probably happened is when the diff was casted they did a fast pour. When you do a fast pour when casting it creates gas bubbles in the molten material. Then when the material cools there’s all these voids in the casting. Then the casting starts to rust out and it ends up looking like that.

Don’t waste your time trying to repair what you have. Get a replacement diff.


It’s actually not that big of a deal to remove the 3rd member, especially on a truck this small

Yes, I work on some pretty big stuff also, for me to say that

I agree that getting a complete replacement rear end may be the way to go here

But I don’t agree that this is due to a casting error

Are you kidding me?

Look at where the leak is.


So the casting must be leaking.



Of course the casting is leaking, because it’s rusted through

But I disagree about a casting error at the foundry being the root cause

It rusted away, probably due to road salt

After all, it’s a well known fact that Toyota trucks and road salt are a bad combination


If the casting is leaking, it must be a bad cast.



It’s downright amazing to me that the paper tag on the differential is in better condition than the differential itself.
Maybe that tag is the only thing holding it together…

As to casting flaws I’ve seen this a number of times from carburetor body castings to differential castings.

We had a Nissan come into the Nissan dealer with a trashed differential traced to a pinhole leak in the casting. After a brand new factory differential arrived I installed it, filled it with oil, and away she went.
A week later it was back with a complaint of leaking and the entire bottom half of the diff. was soaked in gear oil.

After cleaning it was allowed to sit a bit on the rack and sure enough, one could see oil start weeping through a pinhole in the casting.
What are the odds of replacing a pinholed casting with a new factory OEM unit doing the same thing?