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#1
Old 08-25-2009, 07:16 PM
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Retapping oil drain plug

So my oil pan is leaking around the plug because the threads seem stripped out. I will need to replace or fix it to prevent oil leaks. It looks like it will be out of my price range to have someone retap the plug.

Does anyone have any experience with self-tapping drain plugs? I believe that it is currently 12mm x 1.25 (so says the Internet, 1999 Toyota Corolla). Do I just buy one that is the next size larger (which number)? Is there a better solution?
#2
Old 08-25-2009, 07:46 PM
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There are oversize drain plugs made just for this situation. Often, but not always, these are self-tapping. For a given thread size (e.g. 12x1.25) there's usually a "single oversize" and a "double oversize." Buy one of each, start with the single, and if it's still too loose try the double. Be careful -- if the double strips out, the remaining options are unreliable or expensive.
#3
Old 08-25-2009, 08:19 PM
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A drill bit and a pipe thread tap are unreliable or expensive? Or is there some reason they won't work in a typical automotive oil pan?
#4
Old 08-26-2009, 12:24 AM
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Quote:
Originally Posted by Leonard View Post
A drill bit and a pipe thread tap are unreliable or expensive? Or is there some reason they won't work in a typical automotive oil pan?

Pipe thread is tapered, and not ment to e put in and taken out many times. and on the thin metal of a oil pan I doubt if it would last. the oil pan drain should be a strait tap and a gasket.
#5
Old 08-26-2009, 06:29 AM
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The taking out and putting in many times isn't really a problem. Just about all the big industrial natural gas motors that I've dealt with have pipe threaded drain plugs, but I could see where a thin wall might mess that up.
#6
Old 08-26-2009, 09:55 AM
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Assuming you are successful at re-tapping, I'd suggest adding a quart of oil and letting it drain out. This will reduce the possibility of any metal shavings doing significant damage to engine internals.

Curious...do you frequent speedy lube- type establishments for oil changes?
#7
Old 08-26-2009, 10:52 AM
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Quote:
Originally Posted by Leonard View Post
A drill bit and a pipe thread tap are unreliable or expensive? Or is there some reason they won't work in a typical automotive oil pan?
Frankly, I don't know, but it's not something that I've ever heard brought up among my colleagues (auto repair pros). If I recall correctly, some of the British sports cars of the 60's actually used pipe thread drain plugs, but of course they were designed that way. In a case like the OP's, if the hole is already too big for 1/4" pipe thread (which I would guess is likely due to its threads being worn down), then it's a significant jump to 3/8". It's questionable that there's enough metal in the drain plug seat area to to accomodate that.
#8
Old 08-26-2009, 10:55 AM
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Originally Posted by SanDiegoTim View Post
Assuming you are successful at re-tapping, I'd suggest adding a quart of oil and letting it drain out.
What I recommend is coating the tap with a thick, gooey grease (like old-fashioned axle grease). Most of the shavings will stick to it, and the tap can be withdrawn and cleaned.
#9
Old 08-27-2009, 02:48 AM
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Have you thought about checking out car parts recyclers (junk yards) nearby to see what you could get a used but functional oil pan for? If the pan isn't too obstructed by exhaust or other parts, it might be a simpler, more reliable fix. Oil pans are held to the bottom of the engine by up to a dozen or more small fasteners. The job would also require either a car-specific gasket, or more likely, a new coating of a sealant that comes from a tube, like silicone.

I found this write-up with google:
http://ehow.com/how_4521018_drop...a-corolla.html

I was a frequent visitor to my local scrapyard when I was driving my 12 year old VW Golf. Good luck, whatever you try.
#10
Old 08-27-2009, 09:13 AM
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Quote:
Originally Posted by Leonard View Post
The taking out and putting in many times isn't really a problem. Just about all the big industrial natural gas motors that I've dealt with have pipe threaded drain plugs, but I could see where a thin wall might mess that up.

that is the problem.
#11
Old 08-27-2009, 12:55 PM
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Thanks guys. I checked Kragen for one and they didn't have anything, but I'll try a larger store. I don't see much online.

SanDiegoTim, yes, it is quite possible that someone screwed it up. My research suggests that I'm SOL as far as getting them to fix it for free but I can call them. They're >200 miles away so I'd need to do it when I go back home.
#12
Old 08-27-2009, 01:54 PM
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How bad is the leak? If not too bad, try a little Teflon tape. It would be a temporary fix, but it should last 3 months, or 3,000 miles. If you can still tighten the plug it should work.
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