Advice needed: freeze/expansions plug for transfer case? (1 Viewer)

[little_joe]

I'm getting ready to drop the transfer case in the 4Runner to reseal it, and have a general question.

The transfer case housing is aluminum. It has 3 internal holes/paths for shift rods; however my configuration only uses 2 of the shift rods. I want to plug the 3rd one.

This 3rd one allows gear oil to pass through to where it can get in the actuator. My thinking is if I plug this hole, and use my new seals on the other 2 shift rods, I should mitigate any leaks for a long long while.

Kind of been casually looking for a plug. The hole accepts a 15mm plug. I am unsure what material to use in this application - steel, brass, aluminum, or ? It'll see heat, gear oil, and the back side will be dry (so corrosion is a concern). Of course, I'll do something to prevent it from coming out if I use a freeze plug; alternatively, might an expansion plug work? (and virtually eliminate it coming out and getting ground to bits; I worry about the neoprene/rubber though)

Thoughts from those smarter than I would be appreciated.

 

[mtweller]

Unthreaded hole?

There's probably an aluminum or brass freeze plug that would fit the application. If possible, i'd investigate tapping it with NPT and a brass plug so you never have to sweat it, but not sure if there's enough meat.

15mm = 0.591" so it looks like 1/2" NPT would be the plug

Or just RTV a freeze plug:

https://www.oreillyauto.com/shop/b/hardware---fasteners-16585/expansion-freeze-plug-25102/expansion-freeze-plug---universal-17585/6c9fad9f97a1?prodAttr_10250=15mm

Ramon

 

[little_joe]

Thank you @mtweller Not sure about tapping it, but that freeze plug may just be the answer, I guess the steel and aluminum should be ok? (Former Rover owner who became all too familiar with eletrolytic corrosion)

 

[GLTHFJ60]

Brass or aluminum freeze plug is what I'd use. Dollars to donuts toyota used aluminum freeze (or welch) plugs.

 

[little_joe]

Thanks @GLTHFJ60 but Toyota did not use any plug, which partially contributes to the leakage I have.

There's 2 "things" that prevent gear oil from getting into the center diff/low range electric actuator: The 2 shaft seals for which I have replacements, and this hole. Now, when I reseal the actuator, I will hopefully eliminate the leaking; however, without plugging this hole, gear oil can still work into the actuator cavity. The actuator o-ring (which I also have) should prevent any visible leaking, but still - gear oil, electronics.

I don't strictly have to plug this hole, thought it may be best to stave off future issues with this 243k mi, 17 yr old vehicle.

 

[GLTHFJ60]

I get that. I was saying given a similar situation, toyota would have used an aluminum freeze/welch plug in an aluminum hole, steel with steel, etc.

You don't want to mix up steel plugs in aluminum bores, or vice-versa.