Stripped Drain Plug on Automatic Transmission Pan
This weekend I decided to do seasonal fluid changes on my '09. When I drained the A/T fluid it looked pretty good. But when I tried to reinstall the drain plug I realized there were no threads left on it. That's an "oh, s--t" moment, because you can't drive the car without being able to refill the pan.
This was a rude surprise considering that the car isn't very old and I've only drained the fluid about 5 times at most since new. I've owned numerous Asian cars over several decades and have never seen threads strip out on a drain plug - ever. The heads of drain plugs can become rounded out over years of service, but I've never had the threads strip on one. And no, I didn't cross thread it - this was just poorly machined, apparently.
I tried several parts stores only to be told that this A/T drain plug is not cataloged anywhere. I tried the generic oil drain plug rack, but nothing was as small in size as this plug. After wasting time with that approach I determined that the plug is a M10 -1.50 thread. I went to a hardware store and got a bolt of that size with a sufficient (17mm) head on it. Fortunately I didn't need to use a tap on the pan threads. I cut the bolt down to length, added a nylon washer as a seal and installed it. It worked perfectly and the replacement bolt looks like it is of better quality steel than the original plug.
If this ever happens to you, that's the cure. As I recall the threading seemed to be very resistant when screwing it in or out, right from when it was new.The pan has very shallow threading and the original plug is a joke, as it apparently is of very poor quality steel and/or poorly machined to strip out so easily.
