Re-tapping Transmission Drain Plug for the Toyota 4runner 3.4L

Tools needed:
Standard tap set, 7/16-14 Tap (3.5" long to clear the crossmember)
Standard 7/16-14 bolt/nut
New Transmission Crush gasket PN: 35178-310
4qts (1 gal) of your favorite Transmission fluid
14mm socket, to remove the old plug
Vice grips (incase the plug wont come out in my case!)
5/8 socket to install new plug!


Well I bought my 1999 Runner at 85,000 miles and I now have 115,000. It’s an awesome vehicle and extremely reliable. To have the dealer take care of regular maintenance is crazy considering how easy it is to do yourself and the amount of money you will save now and in the long run.

It was time for my Transmission fluid to be changed, so I set off to do a drain and fill (4qts). I live in an apartment complex and had to act fast so I would not get in trouble for draining fluid from my vehicle (sucks I know!). Anyhow, I was in such a rush, I just whipped the plug off and went to reinstall it without checking the threads on it. As I was reinstalling it, I realized it was going in and would not get hand tight. I was amazed and began to become worried. Pulled out the plug and low and behold, stripped beyond recognition! (See pic) Luckily the parts department was still open so I jumped into my girls car, got a new plug ($5  ) only to realize it is stainless steel! The pan too is stainless steel…bad combo IMO. So 20 minutes of trying to get the new plug in, I was forced to re-strip it so I could drive my Runner. Needless to say it would not tighten all the way with a socket, it just kept spinning. A day later I looked and found red fluid on the bolt and said AH CRAP!



A new pan is around $130 and no way was I paying that. So I asked around Yotatech and received advice to re-tap the plug. Only thing is, no one knew what to re-tap it with. Some mentioned a heli-coil tap but that too is expensive, so I went with a cheap bolt from the local hardware store The stock bolt size is a 10mm (the head 14mm) and the next metric bolt size is 12mm which really looked to big to use to re-tap. So the next size between that was a standard 7/16-14 bolt (the head 5/8”). I had to use the old plug in comparison to cut the bolt to the desired length. The 7/16 nut was put on all the way and when I cut the bolt, was used to clean and re-thread the end of the bolt (Smart I know!!). In case you’re wondering, 7/16-14, the -14 is the thread pattern so they must match…bolt and tap or your back to square one.

I borrowed a friend’s standard tap set and went to the local auto hobby shop. Put her on the lift, and removed the bolt. This was a chore as I had to use vice grips and kind of put my weight into it as I turned it so it would come out (yes that stripped!). Then I drained the fluid until it slowed down by about 80% and started to re-tape the plug with a 7/16-14 tap (your going to get a little messy). After through the hole, the left over fluid (quite a bit) flushed out any remaining debris and for good measure, I put a magnet in the hole to catch any remaining shavings left behind, which was none. I installed a new crush gasket and the new bolt and it actually tightened to recommended specs! I was thrilled and still am that I was able to save money and possibly help someone else out in the process of writing this. After all, this is what it’s all about!

 

Good job on that, glad it worked out.

 

Good idea!

 

thanks! it was concerning making sure i had everything right the 1st time so i wouldnt be stranded. i did and i am soooooo glad now...peace of mind!!

 

i had this problem when i did my swap but fortunately i caught it before stripping the whole completly so i just used a 10mm tap to straighten the threads and then got a new plug

 

I love having a tap set, comes in handy sooo much. Harbor freight has decent ones for pretty cheap.

 

I just did the same thing worked great, although i did not cut the end of the bolt off. And yes you do get very dirty.Also, used a copper washer instead of a crush gasket. A little piece of advice, make sure the tap is long enough to clear the cross member when you twist it. Made that mistake and had to go back to Lowes to get a different longer tap.

 

good point, mine was just barely long enough...what size did you get so i can put it in with the tools info?

 

my first tap was 2.25 inches long way to short, second one that worked was 3.25inches. However for the last few twists is had to take on half of the handle off and spin then remove and reattach other way and spin. i would recommend a tap of about 3 and a half inches total length

 

thanks, changed it!