Removing rounded hex

That's a great idea. Being able to remove the part the plug is stuck in is a luxury not afforded in most situations. Take advantage of it!

 

Try some valve grinding compound. Fill in the hole, then tap in the proper size allen key with a hammer.
Not too hard. Then put pressure on it to loosen it as you tap on the key. The compound will bite into the material and
hopefully the tapping will shock it free.
You might also try a hammer and chisel. Use about a 45 degree angle along the edges. Maybe it will slowly
break it free.
How did it get rounded?

 

When you get the drain plug removed, check the washer you’ll be putting on for any opportunities .

Someone out here had that happen once.

Good luck and keep us posted .

 

Just unbolt the small block its mounted on and drill out the center of the bolt and tap it with a longer smaller bolt thread and put a nut at the beginning of the bolt and put a wrench on it and back the whole thing out. Also you can go to the salvage yard and get a new cover or just order one from toyota online. When all else fails take it to a shop.

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Recently I removed a rounded hex nut (different vehicle, different situation) by, as previously described, a large flat (no curve to it) sharp toothed vise grip pliers. The kind I used was Milwaukee brand and has a red handle extender that has a hole in it for really torquing down on the red shaft-handle extender. By placing a screwdriver in the hole and tightening it to the max, the straight sharp teeth of the pliers dug into the rounded hex head. A steady unscrewing of the pliers/hex head did the job for me

 

OH, BTW...spray spray spray with JB Blaster and let it soak soak soak before going to it. Also, some heat to it might aid...

 

Had this happen. I used multiple sprays of penetrating oil and let it sit for a day. Next day I used a hammer and chisel on the edges of the bolt and it turned free after some good whacks. Patience was the key.

 

The thread of the plug is M18x1.5, which means that it's about 3/4 inch in diameter. I'd drill a 3/8 inch hole starting with a smaller hole) through the middle and use a square taper broken bolt extractor. Fluid will drain out (up to 4 quarts). Be sure to use a magnet to remove the swarf. BTW, the plug is tightened to about 30 ft. lbs.

 

One thing, if the panel comes off, try to find the form-in-place gasket spec, assuming that's the sealing method. Dealership service department might be able to find that for you. It might be the same as the engine oil pan FIP gasket (info below), but so far I've been unable to find anything on transaxle assembly:

Toyota Genuine Seal Packing Black, Three Bond 1207B or equivalent
* Remove any oil from the contact surfaces.
* Install the oil pan within 3 minutes after applying seal packing.
* Do not start the engine for at least 2 hours after installing the oil pan.

 

I vote hammer and chisel. No penetrating lube required.

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Go to Harbor Freight Tools. You can purchase a drill kit that drills into the bolt, self-locks in place, then, your reverse drill out. Don't worry about ruining the old thread lines. The drill bit makes a new thread for you. Works like wonders!

 

I have used this! It really works!! You can buy it at Harbor Freight Tools!

 

Those bits work just like in the situation in that video - bolt freshly over-torqued. If you’re dealing with something that is seized on due to corrosion - not the right application. I got a lesson on this from the machinist I used to extract the broken off extractor from the seized in bolt. Apparently, the correct method is to drill with progressively larger bits or weld on something that you can get a tool on. Probably lots of techniques that work.

 

If all else fails: buy a fresh plate (the small plate the transaxle coolant drain bolt threads into), drain bolt, washer, and a tube the spec'd FIP gasket. Take off the old plate (with the drain bolt, clean up the mating surface, install new.

The mystery though: what's the part number for that plate (and is it readily available), the spec'd FIP, install instruction, and the torque value for the plate's bolts. I'm stumped, browsing a pdf Repair Manual; maybe @Elektroingenieur can glean.

 

It’s not; read on:

The No. 1 Motor Water Jacket Cover Assembly is sold as a kit (G1020-47010) containing the plate, six bolts (91551-80820), the drain plug (90341-18016), and the non-reusable drain plug gasket (90430-A0003).

The Hybrid Vehicle Transaxle Unit section of the Repair Manual (more info) has details of disassembly and reassembly. ThreeBond 1282B coolant-resistant seal packing (08826-00100) is applied in a 1.5 mm diameter bead in a specified area and the six bolts are torqued to 18 N·m. The coolant drain plug is torqued to 39 N·m.

(The transmission fluid drain and filler plugs, for which the plug and gasket part numbers are the same as those mentioned above, are torqued to 50 N·m.)

Parts catalog reference: Figure 39-01, Transaxle Assy, HV or FCV, illustration 2.

 

Many thanks sir!