For all you ZF Transmission owners the drain and fill plug was originally an aluminiom screw plug that accepts a 17 MM hex Allen wrench. Harbor Freight has a set of metric Allen wrench, 1/2 drive socket with the largest socket being 17mm for $9.95. A great buy.

 

My last post about tapping a new drain in the trans was not just academic- I have a 93 six speed myself. I just bought 2 quarts of Amsoil synchromesh transmission oil to replace my old oil, so I may be facing the same dilemma. Some of the advice I've seen like 'put a pipe wrench on it' doesn't sound realistic- what will the pipe wrench teeth grab onto? 2 or 3 threads? I've got a humongous pipe wrench in my tool kit, but it when I'm at a point that I need it (last resort time), it needs something substantial to grab onto.
Has anyone here actually laid on their back under their transmission and held an 8 pound pipe wrench against this plug while turning it? I might be finding myself in the same situation in a couple of weeks, and I'd like to know if this really works.
Thanks!

 

These can be found at AutoZone, and probably other auto parts stores.
With the right tools, these plugs are not that hard to get out.

http://greatnecksaw.com/product_info...12-drive-tools


helphos, your right about the pipe wrench.
When the plug is in correctly and in good shape, there are not more that a few threads showing.
So, very little room to get a pipe wrench on.

 

JM95- You got that right! I just bought a set of allen sockets from Harbor Freight with the 17mm as the largest. They're good quality tools.

This thread is not just an academic exercise for me.
Here's my plan:
First glue a strong magnet into the drain plug and drive for a couple of weeks, hoping that any metal junk will gravitate to the drain plug.
Second, raise the car as high as i can and remove the fill plug.
Third, attack the drain plug with whatever allen wrench fits (17mm or 14mm according to this thread).
fourth, put a pan under the trans (dang, oil on the garage floor again. I should have got that pan down earlier!)
fifth, see if I can snake a five foot long clear vinyl hose from the transmission fill hole up the firewall to daylight so I can fill the trans via gravity and not from underneath with a pump.

Replace drain plug, fill with Amsoil, then replace fill plug.

I think it's worthwhile trying to find an easy way to gravity-fill the transmission. I've done it both ways, and it's worth taking an extra few minutes to see if I can fill with a funnel from the engine compartment versus underneath.

Members who have a garage lift need not respond! :-)

 

I don't have a lift, so I changed mine in the driveway.
When you raise the car, it's important to keep it level. It needs to be level to check the fill accuracy.

Both the drain and fill plug came out without any issues at all, using the 17mm hex socket I posted in the link earlier.
The ones JM95 mentioned from Harbor Freight should be similar.


When replacing the plugs, I used just a little bit of teflon tape.
Don't put so much on that you risk getting it inside the transmission.
Just one or two wraps around the threads is all you need.
The tape is not so much for sealing the threads, as it is for making it easier to remove the plug the next time.
A small dab of anti-seize (like used on spark plugs) would also work.

 

hahaha, this is funny because i broke one off in the left head of my L98. ended up having to pull the whole motor out, in doing so i found other problems... 8 months later i still don't have my car back from the shop.

 

Yeah, once you leave the reservation, you're on your own. Some suggestions are dangerous, some are stupid. A few are inspired. Take your time, calm down, put a plan together.
The hex in my plug was stripped, and the few threads showing were gouged from some other idiot's unsucessful attempt to get the plug out.
Solution- use Kroil (best penetrating oil ever) use the correct 1/2" drive 17mm socket I had already, insert it the best you can, and put a longer lever on it (breaker bar). I'm laying on my garage floor with no room to work, too. I finally won.
Remember, pipe wrenches work by pinching the pipe. You're going to distort and semi-cruch the plug and it won't want to turn. Then you're really f-ed. They don't put the pipe wrench on the pipe threads, they put it up the pipe away from the threads where a little squeezing and distorting the pipe doesn't matter.
Plumbers tools are for plumbers. Mechanics tools are for mechanics. Vise-grips - it's you against the spring inside holding it closed. If you overcome the spring and it snaps open, you're going flying hand first or headfirst into the bottom of your car.
Let's be carefull out there.

 

Interesting read for me - haven't done this to my C5 Z06, but did do it to my wife's 03 Chevy Trailblazer (auto tranny). Ended up dropping the whole pan just to change the tranny fluid leaving the stupid stripped drain plug in it!

 

What good are new hex head sockets from Hoarbor Freight or anywhere else going to do if the Hex is rounded out like the OP stated his is?
My drain plug is also rounded out. When it comes time to change the fluid I'm going to weld something on the plug so I can turn it out with a little heat and a wrench or socket.
Bill the ZFDoc sold me a new drain plug at a great price, give him a call. His company name is ZR51 Performance.

 

Drill a hole through the center of the stripped plug and tap it for a 1/8 inch pipe plug. Make that your new drain.

 

idea Pete. I was hoping you'd chime in.

 

The plug is aluminum is it not? Even if you have an aluminum welder the weld will be pretty soft. To bad someone doesn't make a standard square head plug in alumunum, or is it okay to use a metal one?

 

As crazy as this may sound...

Tighten the plug first.

Just a little bit, then loosen it.

Also, another good trick I found was to use dry ice on the plug. The cold shrinks the plug a little, and makes it easier to get loose. It is MUCH safer than using a torch to heat up something that (might be) covered in oil. To make this work even better, drive the car for a while and get the transmission hot. Then apply the dry ice to the drain plug. It should come out really easy then.

Dry ice can be purchased at just about any grocery store nowadays.

And for one of those guys that asked why they didn't make the ZF plug external like the older Muncies...

The C4 ZF sits A LOT lower than a C3 ever thought of...how do you think that AL trans case would like a square plug catching on a speed bump (or curb at the race track)?

Good luck with it...

 

I've had to weld an 19mm allen in to get it out.

 

torque is around 25foot lbs (but check the service manual). Shops over tighten the plug...

 

Bluewasp, you're right. 26ft./lbs. Mine had to be at least 100ft. lbs. tight. I do the wheels with a torque wrench so I know exactly what 100ft/lbs feels like, and this was tighter than that. Like I said, it was a battle - I won.
Good luck to all - just be careful.
Drilling, tapping, aluminum chips in the fluid flying around the trans. You're on your own.

 

Thanks to RollaMo for the tip on teflon tape on the threads. I've got some of that layin' around. I'll use it on both plugs, assuming they come out OK!

Thanks too, to Pete for the thought about tapping the center of the drain plug for a 1/8 pipe tap. The only caveat is that it would be hard to use a normal pipe plug in that hole- most of them have square external heads. You can find them with internal hex (allen) configurations, but not easy to find. I happen to know that's what they use in Ford Explorer auto transmissions (2002 Explorers, at least).

 

The allen head plugs are in every set of freeze plugs for a small block chevy. Autozone and others have them on the shelf. Availability is not a problem.

 

It was the ZFDoc that provided the pipe wrench suggestion (thru me and others). And, with the ton of ZFs he works on, he said he's never had that method fail to get a stubborn plug out.

That said, I'm a skeptical type -- like you. I varied this method by using visegrips. Because I'd already bought the HF hex socket set (as mentioned in the post at the top of this page), I took the 17mm socket and stuck it in the plug. By clamping onto the plug -- with the hex-hole filled, there was way less chance of the plug collapsing in on itself. The hardest part of that method is that visegrips are shorter than the pipe wrench -- providing less leverage. But it worked.

There are also several sizes of pipe wrenches out there and you don't have to use the biggest ***** out there. Pipe wrenches, by design, increase clamping pressure as you increase torsional forces. That's why they work on (relatively) soft lead/black pipe.

Once you get a plug out, you'll probably be surprised at how many threads are exposed and available for grabbing/removing of the plug(s).

FWIW: In my case, I tried big-azz channel locks first. They partially squished and mushroomed the plug edges inward. After that, I used a punch/hammer to reshape the hex center, tapped in the 17mm socket (which easily stayed inside the plug), clamped on the visegrips and went to town.

Putting a 17mm plug in the hole seemed to help my success -- since it effectively turned the plug from hollow to solid. I also liked the visegrip option better considering how it (more) equally clamps onto a round object. Obviously, a pipe (or some other extension) could be used to increase torsional leverage for removal of the plug. (IIRC, I used a hammer and moderate tapping, on the end of the visegrips, to break things loose).

Oh yeah...on this heat thing. Heating the case AROUND the plug while cooling the plug itself is the only combination of hot/cold that makes sense to me. Expand the hole and shrink the plug -- for maximum thermal advantage.

 

One post said to use brake cleaner and then heat with a torch NO ,NO, NO, DON'T EVER DO THAT!! There is some chemical in brake cleaner that will produce DEADLY gas when exposed to a flame and it can KILL you! If you use a torch on anything don't have any brake cleaner on it for sure.
How I got mine out:
My plug had previously been wallowed out by the previous owner so the Allen didn't fit very well and would have only completed the rounding. Looking at most of the Allen head sockets, they have a little chamfer on the end that keeps them from seating deeply into the plug anyway. I went to the hardware store and bought a really short 17mm bolt and two 17mm nuts. I used loktite and jammed the two nuts onto the bolt and locked them all together together. I ground the head of the bolt till it was perfectly flat so it would bite all the way to the bottom of the plug and banged it in there with a plastic mallet. I could then turn it with a socket and big ratchet.
By the way, I liked your idea of holding the tool in there with the floor-jack!:thumbs: