Bulvot

The aluminum plug for the front tow socket on my '87 S4 is stuck, and has been since I bought it in '09. I've tried soaking it in PB, using a pipe on a allen socket, and an impact. All efforts have resulted in a broken allen socket but no movement of the plug.

I've read through all of the threads that I can find on removing a stuck plug in the front tow socket. Based on those, my current second or third choice is to use a reverse drill bit to drill out the core, then pick out the remaining material from the threads.

But I was wondering if anyone has tried (or has best guesses on the success of) using heat on the outside of the tow socket to try to get the dissimilar metals to expand at different rates and break lose. I have some very focused heat available (more focused than a regular torch), but of course there is still the risk of torching things close to the socket.

Or, what about welding an aluminum hex nut to the plug to provide the ability to put a bigger and stronger socket on it. Has anyone tried it? Any thoughts on that?

I'm determined to make that front tow socket functional. Even if I end up welding a new socket to the front of it.

V/r,
Chris

Jim M.

Others have passed this way before you. I know of no one who have successfully removed one of these without drilling them out, myself included. Once you get it out throw it as far away as possible. Then replace it with the rubber plug just as Porsche did with the later models.

dr bob

Chris--

There isn't room to weld anything to the end of the aluminum plug without removing the front bumper cover.

Heat might help loosen the bond, but you'll need to cool everything off before you apply any torque. The aluminum plug expands faster than the steel boss it threads into, so differential expansion with heat fights you in this case.

----

I broke the end of a hardened Allen impact driver in the end of the plug on mine. I ended up drilling a series of 1/8" holes in the plug around the broken driver end. Then carefully worked my way up to a 9/16" drill, just shy of the minor diameter of the plug threads. Then picked out as much as I could. Followed it with a loaner tap, plenty of lubrication with the tap, and was able to restore the functionality. Mine's packed with grease right now, and a couple rubber plugs are on my shopping list with the next parts order.

When you get to working seriously on this task, get the car up as high as possible to you can sit comfortably to work on it. My early efforts were ptough, trying to balance on one elbow laying down, drilling at the same time. Once raised a foot or three, access was suddenly so much easier and safer. Also, spend a minute with some tape, protecting the surrounding painted areas. A little drill wander or a slip will do paint damage that you won't like.

Leon Speed

Do not apply too much grease. The rubber plug will work it's way out with too much lubrication.

dr bob

Right now the grease is doing stunt-double duty for the plug. I'm almost tempted to try a rubber expansion plug, the plumbing piece. Or a marine hull drain plug, with a T on the end to tighten/loosen the plug. That way I could keep it packed with grease for rust protection, yet keep a plug in there securely between "uses".

So far only one opportunity to use the tow eye in the front, when the fuel pump relay gave up at the bottom end of the driveway a while back. I ended up getting pulled backwards up the hill instead. The offending front metal plug was out shortly thereafter.

KLVA

Yep ....Drill it out....

Clean up threads and put some antiseize in there
It's open to the rear, so just let it be empty
Just my $.02

Bilal928S4

I have heard that the plug goes into a cavity that is part of the structure and is not open in the back. I would suggest drilling a small hole in the middle of the plug. Use the small hole to put pb blaster or other penetrating liquids to the back of the plug where the corroded threads are. Using 50/50 solution of transmission fluid and acetone works best (per Wally).
This way you can still use the hex to put torque to remove the plug

marine928

I like the Bilal's idea the best. Am going to try it this week when I replace the rear torque tube clamp bolt.

dr bob

Just a casual reminder that acetone-and-atf is a "penetrating lubricant". It does not dissolve, remove or convert any existing corrosion products. The acetone thins the atf so it will flow by capillary action into tighter spaces, then the acetone evaporates leaving the atf as the lubricant. ATF is about 5W on the motor oil scale, has lots of detergents, so it's about the perfect lubricant for the duty.

The aluminum-into-steel tow eye plug suffers from galvanic corrosion trypical in dissimilar metals when water is added to the mix. The aluminum oxidizes and the oxide packs the threads, wedging them in place. While it may help a little having the lubrication in there, the oxides will still be working to keep the plug from turning.

The threaded boss that is the socket for the front tow eye has a small hole in the back, at least on my S4. If you are concerned that yours doesn't, follow Bilal's guidance and drill a small hole through the plug and all the way through the back of the socket. Then treat it liberally from front and rear with whatever product you feel will help you clear the old threads most easily. DO THIS BEFORE YOU BREAK OFF AN ALLEN KEY IN THE PLUG.

Consider drilling the hole out to up to 1/2" or to whatever your largest EZ-Out or pipe plug extractor tool will fit. Go to 9/16" or so and you are pretty darn close to the minor thread diameter.

Bulvot

Thank you for the input. It sounds like drilling it out is going to be the best solution. And putting it on the lift will make it much easier to work with.

V/r,
Chris