I Have a Stripped Oil Drain Plug! Help!
Routine oil changes are an essential part of keeping your engine happy and healthy. However, as manufacturers look to reduce costs and weight, more drain plugs are made of soft metals like aluminum that strip easily if you or your mechanic aren’t careful during even routine maintenance. A stripped oil drain plug can lead to major engine failure, so take a moment to learn about the best practices for avoiding it and what your options are for repair if it’s too late.
Tiny Bolt, Major Disaster
Your engine needs oil to run. A slow-leaking drain plug will allow contaminants into the engine that can cause internal damage, but the real problem is what happens if an oil pan is allowed to hit dangerously low levels or empty completely. Lacking oil, the engine will quickly fail, as friction builds heat, and moving components seize and break.
Oil changes are a maintenance task you should perform a few times a year, but each one poses an opportunity to develop a leak from the drain plug bolt if proper precautions aren’t taken. If you notice a leak coming from the plug, it’s never OK to ignore it.
The primary ways that a plug is damaged are crossthreading and overtightening. Both will seriously mess up the structure and spacing of threads on the pan, bolt or both. Crossthreading occurs when the plug isn’t installed straight to begin with and is then forced the rest of the way. Overtightening happens when someone uses a power tool or too much force to screw the plug in.
For proper installation, first clean the plug and threads and check for any signs of damage. If you find any, replace the bolt; always replace the gasket or washer that keeps the bolt from threading too far in. Next, tighten it by hand as far as you can — this should be most of the way. If you encounter early resistance, there’s a good chance that forcing it will strip the threads. Lastly, always torque to spec using the proper tools. Your owner’s manual should have all the information you need.
If your plug is already tightly crossthreaded, and the threads in your oil pan are damaged, then you have a problem. First off, it might be difficult to remove, so avoid using vice grips, as those may strip the head. Use the proper-sized socket with the right number of sides. Once the damaged plug is out, a rubber plug can serve as a temporary solution, but shouldn’t be relied on long term.
Your options for repair depend on the severity of the damage. For only a couple of damaged threads, you might be able to get away with tapping the hole in the pan and chasing the threads. If it’s worse, you’ll have to drill, tap and install a HeliCoil. Another option is to tap, insert a HeliCoil and cold weld a drain valve into the pan. If your best efforts fail, you’ll have to replace the whole pan.
Obviously, it’s best to be careful and avoid damage in the first place. But it’s good to have options if something goes wrong. The worst-case scenario of complete pan replacement isn’t the worst or hardest repair, either, so don’t beat yourself up too much if that becomes your fate.
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Photo courtesy of Wikimedia Commons.