Drain Plug Stripped the Oil Pan Threads


Old 03-06-04, 03:28 PM
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Drain Plug Stripped the Oil Pan Threads

1994 Toyota Camry
4 cyl
135,000 miles

I have a toyota camry in which I just changed the oil. When I put the drain plug back in and tightened it up, I noticed that it wouldn't tighten as much as I wanted it to. When I took it back out, I a long metal shaving in between the threads of the plug that had wrapped around several times. I examined the plug and it appears that the shaving came from the threading in the oil pan, not the plug itself.

My question is basically how to fix this. The drain plug is back in and generally pretty tight. I would prefer that it was a little tighter although I sometimes over-tighten things. How tight does this plug need to be in there? Also, I would prefer not to have to purchase a new oil pan and install it. Maybe I could rethread the pan with a rethreading kit. Or, maybe I could wrap some tape around the plug and tighten to further seal it up.

There is already a rubber washer on the drain plug that is doing a good enough job of keeping the oil from leaking. Any suggestions?
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Old 03-06-04, 03:42 PM
Join Date: Jun 2002
Location: Long Island, NY
Posts: 1,531
Use a 1/2x20 universal drain plug from a real auto parts store. Us a 1/2x20 tap to rethread the pan.

Last edited by toyotaman11769; 03-06-04 at 04:58 PM.
Old 03-06-04, 04:57 PM
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Join Date: Oct 2003
Location: Boynton Beach Florida
Posts: 2,207
You may have to go to an oversize plug for that. It sounds like you've already pulled all the threads out and since you can't put metal back in, I doubt you ever get it to it's original size. They make slightly oversize, self tapping drain plugs for that purpose. Of course the new oil pan is the correct and proper way to do it. You will likely have problems in the future if you don't replace it.
Old 03-06-04, 07:20 PM
Join Date: Aug 2003
Posts: 478
No need to change pans. You can fix it better than new if you take your time and do it right!!!

All you need to do is find a prain plug that is slightly larger than the original. Go to the dealer and measure a new one with a caliper. Then find another new one that is slightly larger. You may have to try other vehicle manufacturers.

You want to find a new plug that the thread root diameter ( bottom of the v of the threads) is the same or slightly larger that the outside diameter of a the threads for a new original plug for your car. If 1/2 x 20 fits this criteria toyotaman has steered you right.

Then get the correct tap for the larger plug. The tap will require a certain drill bit size. The drill size may be stamped on the shank of the tap. Drill out the hole being with the correct drill size very careful to go in perfectly straight. Coat the drill flutes with grease to catch as many shavings as you can. You should not need to remove much material at all. Then coat the groves in the tap with grease to catch as many of the cuttings as possible. Then tap the hole making sure you go in PERFECTLY straight. Use a tap handlle to make it easier to go in straight. If you try to use a crescent wrench you will probably not go in straight.

Some factory drain plugs have a built in o-ring. Many GM vehicles use these. These seal the best. Second best is to use a nylon drain plug washer.

If you do this correctly it will be stronger than the original and so much easier than changing pans.

The self tapping plugs Desi mentioned may work but they are not a good long term solution.

Now do not get carried away and over tighten. The manufacturer specifies a torque for the drain plug. Many people over tighten and cause the problem you have.
Old 03-06-04, 07:28 PM
Join Date: Jun 2002
Location: Long Island, NY
Posts: 1,531
The original plug is 12x1.25mm

If the threads are stripped out the 1/2x20 tap will thread in without drilling. Then screw in the 1/2x20 drain plug with a nylon gasket
Old 03-07-04, 03:44 AM
Join Date: Nov 2001
Location: North Texas
Posts: 2,345
after fix

After you fix it always use a new crush washer you dont need to crank down on the plug just make sure it is snug.New crush washers are cheap buy a few at a time.
Old 03-07-04, 03:21 PM
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All fixed up

Thanks for all of your suggestions. I went to the auto parts store and picked up one of the self-tapping slightly larger drain plugs. It screwed right in and it stopped the leaking. Those things are really a good invention. Thanks again.

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