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Front Differential Damage on 2014 Subaru XV Crosstrek

I recently brought my 2014 XV Crosstrek with 171K miles into the dealership to have it serviced (oil change, F&R diff service, R&B wheels, etc.). During the service it was brought to my attention that a crack had developed in my front differential (specifically the Differential Overflow Plug) and that I had to buy new transmission for $9000 as the CVT and front differential are part of one assembly that can only be replaced together. Given the location of the damage, I feel like the service department should own the cost of the replacement as the differential was fine prior to servicing, but they are maintaining that the damage is not their fault. They put some epoxy around the crack to reduce the leaking fluid from the differential while I figure out what to do.

Some additional information: I had my CVT serviced in August of 2019 and no damage was observed to the front differential as part of the final inspection. So I know it was fine then and it has only been worked on at that location.

My Question here is: Does anyone have any experience with a differential cracking through normal driving? Is this something that “can just happen” or is this the result of negligent servicing? Am I way off-base with my request that they cover the entire cost of repair?

Most dealers do not do patch type repair just because they don’t want the problems that can happen if it fails. Look in your owners manual for corporate contact and at least see what they can do to help.
If not satisfaction there then maybe a independent shop might have some way to stop the leak.

It might have been from the service, hard to say for sure. If you end up having to repair it, I would just seal the area with JB weld or similar product. As long as the fill plug is still okay, you can still service the unit by sucking out the fluid versus draining.

JB Weld, I agree. The original formula, not the quick-dry. Do all you can to clean the area inside and out of oil. Dremel a gouge centered on the crack. Hit the area with a blowtorch to burn away any oil in the crack. Let it cool and apply the JB Weld per instructions.

I used it on a cracked block and coolant leak on my 1979 Toyota 4X4 20R and it held fine for years.

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I did the same thing on an 82 ford truck one time it had a hairline crack between # 1 and 2 cylinder on a 300 6 cylinder it held for over a year before I got rid of the truck.

The only time I’ve seen a front differential problem on a Subaru was when someone botched an engine oil change and inadvertently drained the front diff. However, that problem manifests itself in a different manner than what you have shown here.

One wonders given the age and miles if the plug was struck by road debris at some point. All that said, warranty is up a long time ago and neither Subaru nor the dealer have any obligation to pay one cent towards this.

I would just allow the JB Weld to remain because that crack is not worth anywhere near 9 grand. It should last the life of the car.

Is this a case where the crack could simply be welded by a good heli-arc welder? Maybe the crack extends from the drain plug up which would make it a little more difficult but that would be permanent. I had a small engine where the rod went through the block and it cost me $10 to have a guy weld up the break in the block.

So just for curiosity, how would a botched lube change cause a crack? Over-tightening the plug or something?

Since the epoxy now covers the crack it’s sort of hard to tell by the photo how significant the crack actually is. I don’t think the CVT case contains fluid under high pressure, so it seems like a properly done epoxy fix might well do the job in many situations like this. If you want to go with an epoxy-sealant repair the job has to be re-done imo. What you got there is only a temporary fix.

As far as what caused it, seems unlikely the damage was done by the shop. But such a thing is possible, and there’s no way to tell for certain. My guess is the cause is either inadvertent damage from road debris (i.e. you got unlucky), or the CVT case had a casting flaw in it at the time it was manufactured. Suggest OP review the following tsb’s, might provide some add’l insight:

02-169-17 (cylinder head casting problem)
16-107-17R (transmission warranty extension)
03-67-12R ( remanufactured CVT may be available for if original requires extensive repairs)

It looks to still be leaking pretty bad. Two good drips one on plug, one below on bolt head. You’d probably need to drain it before any epoxy attempt or it’ll never stick due to constant oil seepage. Personally, I’d drain it, clean it up and assess the crack. Likely, I’d weld it. If the crack is along the plug boss, the plug will stress it and surface epoxy may not hold all that well. Not a huge deal to weld it.

My hunch is severe overtightening of the plug, maybe without a washer, using air tools.

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I suspect the dealer damaged it when removing the overflow plug to change the fluid. I do not see how that can happen otherwise.

If it is cracked completely under the epoxy, I’d say it would be hard to cause that by servicing, even if the bold was overtorqued. It was either hit by something like road debris or it had a casting defect that has just now appeared.

Since it is only in the casting, I would find a good welder and have it TIG welded and then the area around the plug can be reshaped with a die grinder and finally the hole re-threaded. It would be as good as new then.

I’d say this would be about an hours labor. You may have to find a welder at a body shop instead of a regular mechanics shop, but not all bodymen can TIG weld. Check around.