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Help With Stripped Drain Plug

Hi all,

Well, I've finally done it. I've pretty much stripped off the filler plug of my '94 Toyota Corolla Manual Transmission beyond repair, and am looking for advice. Here's what I've done so far:

- Thought that this gear oil change would be just as routine as the other few I've done on the same car. I loosened the drain plug first (Mistake #1) and then went to loosen the filler plug. Drain plug came out no problem, I stripped the filler plug with a 12-point combination wrench (Mistake #2.) So now I have a car with no gear oil, and a stripped filler plug.

- Thought that using a 6-point socket might help, so I went out an bought one, but that didn't really work -- the bolt was already too stripped. I hammered on a smaller 6-point socket and tried an impact wrench, hoping to break the bolt free (Mistake #3.) After this, I was left with an almost perfectly round drain plug.

- Now, I consulted google, and found a lot of good ideas. I tried using a dremel tool to cut a slot in the plug to use a flathead screwdriver to get it out. Cut the slot no problem, but couldn't get enough torque. Plus the plug diameter was much larger than the screwdriver, so that didn't help. Tried to use the dremel to cut the head of the plug back to something that resembled a hex bolt (Mistake #4) but that was easier said than done. Another idea was to cut a notch in the side of the bolt and hit it with a screwdriver or chisel (Mistake #5 -- BIG MISTAKE) I thought this was a really good idea, but I managed mangling what was left of the bolt head seemingly beyone repair.

Here's where I am now. I realize that I am going to have to drill. I wanted to avoid drilling because this is the transmission and I didn't want to risk getting ANY metal shavings in there, but this is a risk I'm going to have to take (of course I'll flush the transmission out as best I can when I'm done.) One lucky break that I might have is that the plug (the "bolt" part that actually fits into the case of the transmission -- not the head of the plug) is actually somewhat hollow. There is a 3/8" hole through it from the factory. This means that my dirlling effort will be minimal -- I just have to drill out the head part that is over this hollow part (make sense?) This will also minimize the metal shavings that I have to deal with.

My plan is to drill this out with a 3/8" left-hand drill bit, on the off chance that the drilling action might loosen the plug. From there I have a few options that I'd like some input on:

So, the "bolt" part of the plug actually looks tubular, with 3/8" inner diameter and approx. 1/2" outer diameter. The best course of action (I think) would be to tap the 3/8" hole with a left handed thread, and then thread a left-handed bolt in there and get the plug out that way. Unfortunately, everything that I have read suggests that the pilot hole for tapping should be 75% of the bolt size intended. Therefore, the existing 3/8" hole would be appropriate for a 1/2" bolt, which would be as big as the OD of the bolt part of the plug.

Something else that I thought of would be to use a heli-coil in the 3/8" hole. I'm not sure if they make left-handed thread heli-coils, so what I could do is install the heli-coil and then epoxy a normal right-handed thread bolt in there, let it dry, and then try to loosen the new boll-plug combo.

As a last resort, I know I can drill out the whole shebang and then just repair the threads on the transmission with a heli-coil, but I would like to avoid that, since I think I can make one of these other solutions work, and drilling out the bolt completely would create a maximum amount of metal shavings in the transmission.

Oh yeah, I did consider ezouts, but I have seen too many mixed-reviews on them and I've never used them before, so I don't want to make another mistake and have a broken off ezout in there to make things worsse.

Any insight to help me get out of this mess would be appreciated.

Thanks in advance,

Joe

Reply to
<jwelser
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As an interim measure it might be possible to modify a drain plug and insert a check valve onto it. That way you can fill up through the drain plug. Easier than turning the car upside down.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs

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Ontario

Reply to
Boris Mohar

Reply to
Mike Behnke

We all wish we could see what you see. I think I would forget all the left hand thread stuff and EZ-outs. I would not give up on making the slot in it again if you have enough meat there yet. And in this situation I would not worry about a little extra grove you might cut in the case. I would get a very large screwdriver with a hole in the handle for placing a bar or a square shafted screwdriver that you could use a wrench on. It just can't be that tight.

Reply to
MaxAluminum

You can go ahead and drill out the drain plug but if you drill it just to the size of the bolt without the threads, you may be able to salvage the hole and not have to re-tap it. You may damage the threads a little but it seems worth a shot rather than just going and drilling out everything first and *then* having to retap it.

Start with a small sized bit and work your way larger. Eventually you'll get to the size where the bolt walls will be very thin and you can get a screwdriver or a pick in there and try to pry out some of the threads from the drain plug.

Your mistake #1 wasn't really a mistake. Even a pro mechanic would have done the same thing.. However, they wouldn't have continued in your symphony of errors.. =o)

Good luck. =o)

-Bruce

Reply to
Bruce Chang

Id get a hose fitting the same size as the drain plung and force the 4 pints or whatever it takes through a hose via the drain plug. Make the hose long so you can do it not being under the car and above the trans. ( I used old air hose and clamps.) Get the gear oil in the plastic bottles wth the tapered end .You can squeze them in. If it calls for 4, use 5.Going slow works better than trying to force it in. Pinch the hose with vise grip as you switch bottles and again near the plug when you switch the plugs You have to be quick. I did this once on an old truck tranny that I couldn't get the filler plug loose. Good luck.

Reply to
TOLYN9

Too late now, but in the future . . . Always use a new gasket. Sometimes those aluminum flat washers get mashed down to the point where they cause the fill or drain plug to stick more tightly. Had the same thing happen when a transmission shop changed the clutch on a '77 Toyota truck. They said it was ready to pick up, but when trying to fill the transmission right at the end of the job, the workers had to call in the boss and it took him about half an hour with grinding a slot and notches for a chisel into the head of the fill plug, and then heating the area with an oxy acetylene torch before it broke loose. I had always used the 10 minute oil change place for oil changes.

Reply to
Daniel M. Dreifus

Here's your solution--oxy-acetylene works magic--when heated, the plug can probably (Not possibly!!!) be removed with pliers. HTH, sdlomi

Reply to
sdlomi

I second the vice-grip idea, or even a pipe wrench, if there is room. Since you already cut a slot in the bolt, try inserting a screwdriver in it sideways and wrenching it out. But be careful since screwdrivers don't take that kind of torque/bending very well. Try the vice grip first.

- Dave

Reply to
Dave

Hi Joe, I just pulled the same stunt on my '91 tercel, but thankfully I didn't drain it before I rounded the filler plug. The heads on those bolts seems way to short to me and seem prone to stripping. Let me know how you get it out. I've thought of welding a bar on the head if I can find a welder, and then heating the whole thing up. Or I may cut the head off to get rid of the friction there, and then drilling into the hollow center of the bolt and using an easy out. Peter

Reply to
Peter Ryan

Yea, but you are sure going to have a mess when that plug pops out.

Reply to
MaxAluminum

Hello Joe, If I'm not too late, go to Sears and look in the automotive tool section for a set of sockets that work like the 'Ease-outs'. I don't remember the name of them they would be called something like 'Extractor sockets' I guess. I think Santa is going to bring me a set for Christmas. ;-)

My son-in-law stripped the plug on his 2000 Saturn and bought a small set of them and said they work great.

Hope this helps, Robert

Reply to
Robert

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