Drain and fill plugs for differentials

I’m going to be changing the differential fluid for both my front and rear diffs. The rear fill plug stripped almost immediately when I tried removing it. So I’m going to wait to change the fluid, but I need to find where to get the rear fill plug. I have found part number 90341A0002, but I want to make sure this is the right one as there is just an illustration. Can anyone confirm if this is the right part number?

 

A quick google search says that’s the correct number for the rear filler plug.

I recently had to replace the front drain plug. I had to weld a large Allen key to the plug then apply a breaker bar to it.

 

Thank you, just wanted to be sure. I'm probably going to replace all of them because they all look welded on. Should be fun.

 

I stripped mine a few weeks ago. I'm leaning towards this route.

 

It was definitely the quickest way to do it, only took a couple minutes. I wasted a bunch of effort drilling into the center of the plug and trying to back it out with an extractor, which just broke.

I think the plug is stainless or some sort or alloy because I didn’t get much penetration into it. I basically melted the end of the Allen key into the hole and threw a bunch of metal around the seam which was enough to grip it.

 

I tried for the life of me to get the front diff drain plug lose. I couldn’t. Soaked it with PB blaster, tried impact gun, tried breaker bar. It’s rusted shut and won’t budge.

 

I've read a lot of front/rear differential fill/drain plug removal stories and I can't help but wonder if:

a. These people live in the rust belt
b. They wait until the clock reads 100K or > to change fluid
c. Both a and b

I've said it before and I'll say it again. Back the vehicle up on to ramps. You now have the opportunity to use a much longer breaker bar.....leverage.

Member @Clearwater Bill recently posted an excellent idea. Use a floor jack, but be sure you have the loosen/tighten orientation right and all is perpendicular. Search for his comment. I'm not going to do it for you.

 

I used a pick and some pb blaster to clean the Allen key hole out. Made sure it bottomed out before i put any torque on it. They came right out...

 

Dealership will have a rear fill plug. I just got one from a buddy who works at a local toyota dealer. I got mine for free, but they cost around $5.

 

I changed all my diffs and transfer case and transmission at 150k....first time ever.

I sprayed all of them with on blaster the night before. The following day I put my dockets and ratchet underneath in the garage floor.

I took a propane torch to one for about 90 secs then immediately put the ratchet on it and unscrewed. It was about as tough as a very snug oil plug.

I plan on changing the oils more often now.

 

Just did my front diff for the first time. Have done my trans multiple times, transfer case once, rear diff twice. I'm at almost 100k. I neglected the front diff for 7.5 years and 100000 miles because... reasons?? Hey, I never claimed to be good at this backyard mechanic stuff...

The drain plug came loose just fine, with a 2.5' ratcheting breaker bar. The fill plug was also fine, with an 18" breaker bar. And believe me, I don't lift weights. Ever. What not-weaklingness I have must just be good genes. And get this - I didn't even jack the truck up.

I would say "a" above applies to me too, at least somewhat. Maybe some people are just lucky? I don't know what else to say.

 

My front diff drain plug was stripped. I had a shop weld a 19 mm nut onto it and it popped right off, cost me $10...allen bolt on the front diff is the all-time stupidest design ever...

 

I am uniquely qualified to contribute to this post. I'm a construction equipment mechanic in Salt Lake City and I've had plenty of hands-on time with equipment that's spend thousands of operating hours at salt and potash harvesting sites at the Great Salt Lake, so I know a thing or two about stubborn drain plugs. There's no need for complicated methods or days of soaking in penetrating oil.

-Always try to loosen the fill plug first. Then if your attempts are unsuccessful the differential is still full of oil and the truck is driveable. Dig all of the rust and grime out of the allen hole with a pick. Clean it out with compressed air or carb cleaner to make sure all of the particles are out. This will help you fit the correct size allen socket.

-Make sure you have the correct size METRIC allen socket and tap it all the way in with a hammer. Using an SAE socket that feels close enough=stripped drain plug.

-Put a breaker bar on the socket and rap the end of it repeatedly with a hand sledge while attempting to loosen it (see attached photo).

Be patient and don't get too crazy. I strongly recommend a 3/8" drive breaker bar for automotive stuff. A 1/2" breaker will tempt you into using too much force and rounding out the plug. I have never stripped a drain plug or failed to loosen it doing it this way.

 

https://www.tacomaworld.com/threads/getting-the-rear-diff-fill-plug-off.553290/page-2#post-18013116

 

I finally did break mine loose. Yes, my truck was exposed to more salt/water in PA than drier climates. But Google'ing around, it turns out stuck Toyota front diff plugs with this weak hex design is a common problem for 4Runners, Tundras, etc., in addition to our Tacomas.

There are some good Youtube videos and other forums that recommend some or all of the following:
- Clean out bit with pick first, make sure hex socket is fully inserted
- Before trying to break loose, apply heat and PB blaster generously
- When that doesn't work or you've stripped the plug (again, a common problem even when being careful due to corrosion of the inner socket) try a T55 Torx bit to grab it better
- Apply heat again
- When the T55 Torx strips the socket further (again, a real possibility), look into the chisel method and hammer a little notch at 3 o'clock to then repeatedly shock it with a ballpeen hammer and flat chisel in that notch.
- Keep trying an don't give up
- I used MAPP gas to heat the surrounding of the plug for 30 seconds and let it cool
- Use a Lexus fill plug (part number 90341-24016) as replacement (see https://www.tacomaworld.com/threads/front-diff-drain-plug-alternate-oem-part.604989/) which has a 14mm hex protuding nut instead of the inset hex. Cost me $9
- You can use a different fill plug as well from Toyota -- 24mm hex, instead of the inset hex. Part number 90341A0002. I think this is the same used on the rear diff.

References:
- https://www.tundras.com/threads/front-differential-stripped-drain-plug.56959/
- https://www.youtube.com/watch?v=hFnOejt3VIU
- - Great thread on Tacoma World: https://www.tacomaworld.com/threads/front-diff-drain-plug-alternate-oem-part.604989/
- https://www.tacomaworld.com/threads/front-differential-drain-bolt-stripped.611719/
- Hope all this info helps others out there. Don't get discouraged, try to be careful at first. Applying heat seems to be proven by many reports, including myself.

 

The last thing you should do is spray some Fluid Film or Woolwax on the plugs to minimize the rust build-up for the next time.

 

I think the hex inset design just won’t last once corrosion sets in on that metal. There won’t be enough grab. Essentially, with enough time and corrosion, the inner edges are eaten away and the true size of the socket is like 12.1 mm or 12.2 mm, and no such socket exists. That’s why even when trying to be careful, you may be doomed. Likewise, the depth is reduced (and it wasn’t that deep to begin with). It’s not about sloppiness. It’s a bad design.

The new Lexus plug should resolve this to some degree so you don’t get into a situation where there isn’t metal left to grab onto. Yes it rusts but there are better ways to grab onto a nut, a little harder to round off.

In my case I’m in a new climate where there is no salt. I doubt I’ll experience it again.

 

I recently been servicing my truck with great help from TW members, and yes, I waited to 100,000 miles to do it clearly as you suggested-predicted… only thing is I bought the truck with 17,000 miles and I could tell that this front plug was definitely out at least once-chewed up a little bit. Someone had done it at 17,000 or earlier and I think they put the wrong fluid in, got GL5 in there now and shifting very good,no more clunking. I think I got lucky being in Arizona with all the heat to loosen the plug a little, but yes it almost didn’t come out. I had to hammer in a 3/8 hex and jack up the lifted truck to get my big breaker bar all the way under there. It literally popped and sounded like i broke something but it was all all good. Thanks for the part number I’m gonna order new plug. Front diff brass washer for the plug is

$3 90430-24003 Front Differential Drain Plug Gasket

90430-24003 and I also found here

$14 12157-10010 Toyota Oil Drain Plug Crushable Steel Gaskets Set of 10 OEM 12157-10010

12157-10010 for the crush washer front diff fill plug and need two for rear diff fill and drain.

 

I believe the correct size is 10mm.

 

19mm or 3/4”?