F250 Rear Diff Fill Plug Seized

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Was preparing to pull the rear diff cover today and replace the gear oil with Mobil 1 syn. I started with the fill plug, didn't want to get stuck with an empty diff and stuck plug. This thing will not budge. My truck is on the ground, I don't have a lift, and I'm not able to get in the best position to work on this thing.

I was thinking of investing in a electric impact wrench but I'm not sure that will do the trick. I've heard of taking off the ABS sensor and filling from the topside of the pumpkin but my understanding is you have to replace some parts of the sensor. Is that correct?

Is there a trick to break loose the fill plug? Road salt and time have really taken a toll. I have a mechanic close by who I could take it to but I was hoping to do this myself.

I also plan on doing the front diff and transfer case. Not off to a good start.
 
Are you using a breaker bar? I'm assuming its a 3/8 inch drive ratchet head you stick in there? If I were you I would get a 1/2 to 3/8 adapter and use your largest breaker bar. Hit it with some Liquid Wrench first.
 
Get the breaker bar after the Liquid Wrench and pull really hard. Make it as long as you can and if it becomes necessary get a friend. But remember to pull, not push.
 
I'd clean it up and soak it with penetrating oil. Give it a day or so to sink in. Soak it in the morning, then again at night. Then give it a try the next day.
 
Originally Posted By: demarpaint
I'd clean it up and soak it with penetrating oil. Give it a day or so to sink in. Soak it in the morning, then again at night. Then give it a try the next day.


Plus use a wire brush first to remove any rust before spraying penetrating fluid. A breaker bar should do the trick. It would be better to use an air gun to remove the plug.
 
I've tried it with a 1/2 to 3/8 adapter plus my breaker bar. Problem I'm having is the truck is on the ground and I'm not getting a good pull with the bar. I've thought about going to Harbor Freight and getting a set of their magnum 16,000 lbs ramps to lift the tail of the truck up some. That should give me a little more room to work with.

I picked up a new cover at NAPA yesterday, wish I could have found one with a drain and fill plug built into it. That would make life so much easier.
 
Originally Posted By: JC1
Originally Posted By: demarpaint
I'd clean it up and soak it with penetrating oil. Give it a day or so to sink in. Soak it in the morning, then again at night. Then give it a try the next day.


Plus use a wire brush first to remove any rust before spraying penetrating fluid. A breaker bar should do the trick. It would be better to use an air gun to remove the plug.



That should work fine. The key is clean it real well and let the penetrating oil do its magic, which takes some time.
 
This is somewhat odd because I think that fill plug has loctite on it from the factory. On my old F150 I strongly recall that the threads had a blue sort of paint on them.

The Torque on the plug shouldn't be much. A 3/8 ratchet head should be more than adequate to take it off.
 
If you cant wait for Kroil to come, try CRC Knock Er Loose. Most Fastenals carry it. That's all I use for parts that have lived their life submerged in salt water and refuse to come free.
 
Fortunately diffs are fairly bulletproof and a few weeks/thousands of miles won't do much. I'd get various penetrants on there and see what happens.

What size/kind of plugs? I've done some old MBs with a 14 or 17mm hex plug, on the ground, and had to use a 1/2" drive bar with a pipe, sitting on the ground, pressing with my legs.

I doubt an impact will help because of angle/fit. These things just aren't that convenient, though a pickup may be better. Not sure where Ford places the fill plug.
 
It may sound silly, but make sure it is turning the correct direction. On my Ranger the rear diff fill plug is on the upper left side in front of the axle, and reaching up and over is easier access when the truck is on the ground. I have to think which way to go because of the backward approach.
 
Originally Posted By: Doog
PB blaster....soak for a day then tighten it a bit then loosen.



+1 and if it still wont budge re-apply PB blaster and wait a couple hours and put a little heat to it. PB blaster doesn't catch fire easily.
 
use a long breaker bar

if needed a propane torch Very carefully to degrade solid threadlocker


Impact might be ok but never on an alum diff like subaru

Try to get an angle where you can hang from end of breaker bar for leverage

Make sure you are going correct direction
 
Put a long extension into the plug and beat the snot out of it with a large hammer. This will crack loose the threads. You will then be able to back the plug right out with a ratchet. Any other method seems silly ever since an old timer taught me that trick.
 
Lot of good advice here. My take:

1. Buy one of these:

http://www.lislecorp.com/divisions/products/?product=157

2. Get a proper pipe pipe plug socket set, make it impact style. Using the drive head of a breaker bar or ratchet is OK but a proper pipe plug socket fits better.

One example:

http://www.ebay.com/itm/Grey-Pneumatic-1308P-8-Piece-1-2-Drive-4-Point-Pipe-Plug-Impact-Socket-Set-/331795807409?hash=item4d40923cb1:g:kocAAOSwP~tW4CRx

3. Wire brush the crud off the plug and surrounding area. Wear safety goggles!

4. Penetrating oil du jour, let it sit for several hours, spray again and repeat till you're bored or it's been a day or two. PB Blaster or Liquid Wrench are what I use with best success.

5. Use proper pipe plug socket on the hand impact tool, get your baddest BFH and wail away.

6. Make sure you have a beer chilling in the fridge 'cause you'll be so happy with yourself at how easy this was with the right tools that you'll want to treat yourself to a cold one.
smile.gif
 
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