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Discussion Starter · #1 ·
I unfortunately have stripped the threads in the front differential oil fill hole. Now the dealer wants me to buy a new transmission. Does anyone know of a simple fic to this? Like re-thread hole to the next size up? Helicoil? What is the easiest way to go for someone with not a lot if any tooling experience. I appreciate all responses including those that mention my stupidity for stripping the hole in the first place.
Thank you!
 

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2020 Crosstrek Limited
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I unfortunately have stripped the threads in the front differential oil fill hole. Now the dealer wants me to buy a new transmission. Does anyone know of a simple fic to this? Like re-thread hole to the next size up? Helicoil? What is the easiest way to go for someone with not a lot if any tooling experience. I appreciate all responses including those that mention my stupidity for stripping the hole in the first place.
Thank you!
Yes, helicoil- to just rethread the hole.
 

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2018 Crosstrek Premium, Sunshine Orange
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What is the easiest way to go for someone with not a lot if any tooling experience.
To expect "easy" is to invite catastrophe. Any fix at this point runs a high risk of contaminating with metal shavings which could cause major damage. The risk can be managed and mitigated, but it might be one of those jobs best left to a really good mechanic.
Now the dealer wants me to buy a new transmission.
Imagine that. The dealer proposes what is certainly the most expensive solution possible.
 

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Yes, helicoil- to just rethread the hole.
Yeah, a properly-installed helicoil will be stronger than the original threads were. But it does take careful drilling and installation (edit: and cleanliness like JoeKerr mentioned above). You'd have to buy a kit for the specific size (18mm threads? not sure), which you may never use again, or take it to a shop who already has an assortment; but it's the right way to fix it.
 

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I stripped the rear diff drain. Sick feeling when that happened and only myself to blame but ended up tapping next size up. Figured the soft Aluminum shavings would be pulverized by the steel rotating gears so was not too concerned about any leftover crumbs but I did flush with extra oil. Used a brass plug I had on hand, Teflon tape and gently snugged so not to strip the new threads. This happened last summer and everything is working (knock on wood/head). I did mark the end of the plug so I could keep an eye on any rotation that may occur from vibration.
The only issue I had with the tap was it would bottom out on the inside of the diff housing. The drain hole was close to a chamber on the inside which really made it difficult to create new threads. It just barely fit and took several gentle tries with the tap.
 
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There are many vehicles that just use a rubber plug on the rear diff fill hole, it's not under pressure or anything. I'd be nervous to do that on the front since it's not as visible.
 

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There are many vehicles that just use a rubber plug on the rear diff fill hole, it's not under pressure or anything. I'd be nervous to do that on the front since it's not as visible.
Having had one on my TJ d35, you do need to make sure rhe plug has some sort of detent the ensures it won't pop out. And you can buy those plugs cheap, so depending on hole size, OP could give it a shot.


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Discussion Starter · #14 ·
Was the hole stripped by overtightening or is it just a weak area? Just wondering so i can keep it in mind when the time comes for our car.
Maybe I would be careful trying to remove it. The dealership told they donat remove them they fill from the rear overflow hole. Wish I knew that one!
 

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Discussion Starter · #15 ·
Anyone see an issue with going from M18 to M20 sized thread for this filler hole? I couldn't find a M19 plug or tap. Again thank you for all the input.
 

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2021 Crosstrek Limited
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The dealership told they don't remove them they fill from the rear overflow hole. Wish I knew that one!
One would think that would be a pain seeing that hole is parallel to the ground. One would have to make sure the fill hose is in a place where gravity wouldn't just drain it right back out.

I don't see how you would have messed up the threads by simply removing it, unless it was cross-threaded when it was last installed. When you broke it loose, were you able to turn it out by hand like -THIS-?
 

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Maybe I would be careful trying to remove it. The dealership told they donat remove them they fill from the rear overflow hole. Wish I knew that one!
I've done the front diff fluid change twice now, and I can't see the issue the dealer described. Filling from the overflow would be more of a pain in the *** then the actual filler plug, I'd say.

How did you manage to strip it? Crossthreaded?
 

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Discussion Starter · #18 ·
That's the video I watched. Mine popped then I could remove it by hand. Maybe when I reinstalled it I over torqued it. But I used the 50nm on my torque wheelchair.
I've done the front diff fluid change twice now, and I can't see the issue the dealer described. Filling from the overflow would be more of a pain in the *** then the actual filler plug, I'd say.

How did you manage to strip it? Crossthreaded?
I am not sure exactly how it got stripped. The dealer said the factory put them on too tight. If you have the giant syringe it would pretty easy to fill.
 
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