Frozen gearbox fill bolt

Any suggestions on a frozen gear box fill bolt?

Pesky aluminium/steel corrosion. Tried liquid wrench to no avail.

Heat & cool?

Impact driver?

Just wanted to see if anybody had something that worked for them....

 

Use a 10mm allen socket with a 3/8 to 1/2 adaptor and use a breaker bar to crack it loose. You won't get any kind of penitrating lube into the thread because of the sealing washer. If the threads come with it, your gonna have to remove the pan and have it repaired at a good machine shop. Good luck!

 

If what Tom suggested does not work you could try heating the case around the plug but dont get it so hot it cooks the oil on the other side.

 

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He's talking about the fill hole, but is it the gearbox fill or the actual transmission fill? Eigther way I would think a breaker bar and slow pressure would do it. Mine was tighter than a nuns butt when I removed it the first time.

 

It's the 12mm hex socket gearbox fill.

Just glad I started with the fill rather than the drain.....

 

Oops..sorry..your right the FILL is a 12mm. I read your post to fast..my bad..

 

You want the shortest length possible on the 12 mm allen wrench so it has the least wind-up.
A ½ in impact 12 mm allen socket with a impact gun is best if you have one.
I’m reluctant to use breaker bars without knowing the quality of the steel in the plug.

I think impact guns are less likely to round out the inhex in the plug.

That’s just one person’s opinion though (with 30 years shop experiance)

For sure localized heat will help

 

Always break the fill plug loose before draining. Good way to avoid empty tranny and no way to refill. On my old Mondial, the first time I changed the tranny fluid, I had to use a breaker bar with a pipe over it to get enough leverage to break it loose. Use progressively stronger pressure, don't jerk it with all your strength. I've also found that tapping the breaker bar with a "persuader" can sometimes crack it loose. Just don't get too heavy handed with the deadblow hammer or you'll snap something.

 

I had this same problem a few months ago. I heated the plug with a propane torch and then used a breaker bar. The plug popped loose and the threads were undamaged.

 

I remember having this problem with my 328 years ago, and I went to change the gearbox oil with another, only weeks later...and I KNOW the fill bolt was not over tightened. What causes this? Would putting a dab of anti-seize on the threads be of any help?

 

Had this a lot with cars in europe.
I agree with the above statements of using a little heat as the aluminum/steel causes a chemical reaction which can effectively weld the two together.

Jaguar used to use steel studs in the water jacket of the block through an aluminum head which made life real hard when rebuild time came along.

Local heat will expand the aluminum faster than the steel which breaks the bond. You can get away with a heat gun if you don't have a propane torch but remember aluminum melts at around 1200 degrees so don't go crazy with oxy acetylene.

Shock will also work but you risk damage so the previous method is preferable.

 

Thats what I always do. For everything.
To get this filler plug loose, you will just have to keep at it till it comes loose.

 

For any frozen bolt I find it helps if you tap on it as though you were trying to drive it further in. In this case some heat, a few good taps (not too agressive), and give it a try. If it still won't move tap a few more times, continue until it cools then heat again and start over.

 

In case the threads are damaged once you get the plug out, I have a lengthened plug that I had custom made . The length is such that it catches the threads which are deeper inside the plug hole. I had it made for an '85 308, but wound up not having to use it. If you need it, I'll sell it to you.

 

When I did mine on the 328 a month or two back I ended up using a hydraulic jack! My fill plug has been replaced with a hex head thing (longer thread than normal I think) & so it was a long box wrench & a trolly jack that finally cracked it loose.

 

Those are commercially made. I keep them in stock.

 

Big fat 90 degree allan, with a 12" cheater bar, placed on a jack.

 

Looking at the number of same posts, this seems to be almost common
but is there a way to prevent it?
Perhaps using anti-seize on the threads?

 

It only happens when they are overtightened.

More things are broken by being overtightened than by being left loose.

If people used torque wrenches on everything they would be shocked at how loose things are supposed to be.

 

Just a simple suggestion,
Run the car upto temperature by taking a drive for an hour or so, and then try to loosen the bolt, while the engine and trans are still hot. The different metals have differing rates of expansion and this is a natural way to get things heated up, without banging and forcing them. It may work, it has for me on motorcycle engine plugs, pour and drain plugs. If not, then the excessive use of force and obcenaties may begin.

Ciao...Paolo

 

There really should be no need for anti-sieze. When you refill the tranny, you are going to fill it to the point that it reaches the fill hole, so there will be oil on the threads. That should function essentially the same as anti-sieze. As noted, do not overtighten the fill plug. Use a new washer, tighten it snug but don't muscle it tight, and the next time, it should come out easily. Also, if you do it as part of your yearly maintenance, the threads won't have enough time to "weld" themselves together.

 

So what torque setting would you recommend for the plug? I used 25 ft/lbs and used anti-seize on the threads for an easy removal next time.

 

To my knowledge there is no torque spec for them but 25 is probably fine.

 

I have been using fiber washers on all of my fill plugs for 13 years and find it makes them easier to open and because of the extra give i think less likely to strip.

JMHO

Rob

BTW If you strip those threads you have to take more than the pan off unless you can get a timesert or heilicoil.