Tech Tip Tuesday: Preventing and Repairing a Stripped Drain Plug

TTT Drain Plug Feature

Honestly it’s pretty much the worst way to end an otherwise uneventful oil change. It doesn’t matter if you’re working on a customer car or your own pride and joy, a stripped drain plug spells a bad day. Most of the time, drain plugs are striped because an inexperienced neanderthal feels the need to hang on his ratchet to make sure the plug is tight. This couldn’t be more wrong! Every drain plug has a torque spec and most are around 10 ft. lbs. or 120 in. lbs. Back in the days of steel oil pans and 1/2″ or 9/16″ drain plugs it was less critical to torque drain plugs, but with the majority of oil pans being made from aluminum, drain plug torque is critical. The head on this Chevy Cruze drain plug is only 10mm, hopefully hinting to the tech that an impact wrench is not necessary for proper torquing. GM also conveniently cast the torque right in the oil pan; it doesn’t get easier than that. Incidentally, 14n.m equals approx. 10 ft. lbs. or 123 in. lbs.

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You can see from this photo that a little less than half of the threads in the oil pan were engaging the drain plug. This caused it to strip when I applied the slightest amount of torque. I think someone stripped this oil pan during a previous oil change and left the next tech (me) to pick up the pieces.

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The right way to fix a stripped drain plug is to replace the oil pan, plain and simple. Oil pans usually aren’t cheap, though, and they are often labor intensive repairs. There are oversize drain plugs that you can use a couple of times as a band aid, but I don’t recommend their continued use as they often leak. These cut new threads in the oil pan, but they can be difficult to start perfectly straight which makes the sealing gasket deform when torqued.

The only viable permanent fix for a stripped oil pan, save for a new pan, is to use a QUALITY thread insert like the ones from Time-Sert. This is a precision tool set designed to produce a permanent oil pan repair, and the results are downright impressive. Hopefully, I’ll never have the pleasure of using a kit like this, but if I do I’ll make sure to do a full review.

Avoid, at all costs, the “universal drain plug.” The only way I would use this drain plug is if it was the only thing available at the time, and I would replace it as soon as humanly possible. I’ve seen these in way too many cars because they’re cheap and easy to use. The problem is that you’re putting the life of your engine in the hands of a friction seal on a rather smooth surface (no threads, remember?) with oil, a lubricant, all over the place. These never seal right and cause way more trouble than they’re worth.

Remember to go easy when torquing your drain plugs from now on. If you are a little nervous, rent or buy an in. lb. torque wrench and use it a few times until you get a feel for the proper torque. There’s no shame in using the right tool for the job and doing things right the first time, even if no one else does. Thanks for reading and Happy Wrenching!

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