Self Tapping Oil Plug

Can't you open up the hole and put a bigger plug? Or maybe change the oil pan?

Those plugs with a drain valve, they are not very good

 

I don't think it's self taping. You have to use a proper tool to enlarge the hole and put a bigger bolt.

The drain plugs are convenient but they stick out, not very flush. So that extra length that sticks out, you can hit it with a rock/debris when you're driving. The new ones are slightly better design where they won't slide open without warning (lose all your oil), they have a locking mechanism now. But these type of accidents don't happen often, but when they do, you lose all your oil without warning.

 

I went thru this once on a Prius C... The oil plug bolts kept getting stripped and leaked so I decided to replace the whole oil pan. But then the old pan was adhered so tightly with gasket seal that I didn't want to charge for extra labor of that wrestling match while under the car. So I bought a Harbor Freight tap and die kit to restore the existing threads as a last ditch effort to avoid the hassle and was successful.

I made sure there was oil slowly pouring out while I cleaned up the threads to ensure metal shavings didn't get left inside. Also used a magnet. Was one of those moment where I realized an easy fix was turned into a big hassle simply because I didn't realize how quickly a tap and die kit could resolve it.

 

I developed this method to reform the threads of the drain outlet in the oil pan to take a NEW OEM drain plug, since the old plug's threads have been deformed.


SIMPLE and INEXPENSIVE stripped Toyota oil pan drain plug hole repair


These methods allow for simple, easy and cost effective repair of stripped out M12x1.25 oil drain pan threads found on nearly all Toyota vehicles.




Method 1 is most effective when a new undamaged drain plug cannot be screwed in.


This method uses an M12x1.25 thread chasing rethreading tap available from Jawco, Lang and Snapon as well as many other tool suppliers. A standard thread cutting tap will not work.


The tap reforms the threads that have been bent out of alignment. A few threads will have been destroyed and will come out with the damaged grain plug, but the majority will only have been bent out of alignment.


A new drain plug will readily tightened to 27 ft lbs with a new Toyota crush washer.


Method 2


This method uses old 1960's standard 1/2x20 fine threaded SAE drain plug used by both Ford and GM in the widely available SAE 1/2x20 National Fine thread. The 1/2x20 tap will allow repair of the stripped threads in the Prius Toyota M12x1.25 threads that have been stripped out.


The 20 threads per inch is very close to the metric 1.25 thread pitch. 25.4mm / 1.25 = 20.32 threads per inch, where 25.4mm = 1 inch, and the metric thread pitch of the original thread in the oil pan plug hole is 1.25 mm between the peak of each adjacent peak. The minor variation amounts to a variation of a negligible 0.016 mm for each thread. In effect, the 1/2x20 thread is a M12.7x1.25 equivalent.


The threads of the 1/2x20 tap only increases the diameter of the threads to 12.7mm which takes only an increase of no more than .35 or approximately 1/3 of a mm off what wr69 measured as 1.5 mm thick at the wall.

 

Yes, absolutely. The treads are deformed and bent down in the hole, while the threads on the damaged plug are bent to the up position.

The tread reforming tool does not cut into the threads, it moves and bends them back to their original position.

The new plug will thread back into the reformed hole with no resistance and the assembly will be good as new.

I have actually performed this repair on numerous damaged Toyota drain plug holes. It works.

 

As @Georgina Rudkus explains, it's usually just a clean up of existing thread size, not the hassle of making new threads and finding a new plug size. Thinking that new thread size challenge what I needed was why I just bought an oil pan for $27 instead. Lesson learned! You can have my oil pan if you need it. It fits on almost all toyota 4 bangers. The magnet was to make sure no metal shavings were left behind in the oil pan.

 

This has been going on since the 22 mm drain plugs way back in 60 KE Corolla. Very cool still goes on today.

 

These are the type of thread of thread chasers That I use,

Lang Tools A & E HAND TOOLS - Metric Thread Restorer Tap Set 6Pc (2588), One Size

They are exceptionally handy if you own a Toyota.

 

Who stripped it

 

On my 2010 gen3 Prius the engine has a replaceable lower oil pan that only costs about $30 from Amazon. Plus there is also a fel-pro gasket you can buy for about $10. I did a quick search and found the pan for gen2 Prius is even cheaper (~$20). I replaced it because when I was disassembling the engine, I had to pry the pan very hard to get it off so it was kind of torted so I voted to replace for peace of mind and considering this low cost. Toyota actually sealed the pan with the silicon sealant (the three bond sealant you can find on the factory repair manual) but I used the fel-pro gasket instead. So far so good. If the drain bolt is stripped I would recommend that you get the pan replaced.

Be very honest I would be cautious about re-threading the damaged thread. Keep in mind any re-threading would create metal shavings and small pieces of metal shavings could possibly find its way into your engine with oil circulation. Not worth the risk.

 

Use a magnet to pick up any steel fragments. We machinist call these cuttings swarf.

Also, have you ever heard of a magnetic frain plug?

 

That's why I'm saying be cautious. You machinests can get this done right but not an average home mechanic.

Keep in mind, the cost of a magnetic drain plug is almost the same as a new lower oil pan in this case. While labor might be a little different though (1 bolt vs 10-15 bolts with gasket surface cleaning), not major difference. Plus the OP has to tap the thread. I would vote for a new oil pan for sure.

By the way, your magnetic pick up method only works on steel pans. There are a lot of engines today made with aluminum pans. Do you also work on that?

 

Using the proper thread chasing tap, it takes no more that two minutes to reform the threads, Onlt a few small fragments of steel comes off. For me, I prefer a softer aluminum magnetic drain plug that would sacrifice itself before bending the drain plug holes again. A new steel OEM Toyota drain plug cost about $5. The aluminum magnetic drain plug; $10,