Okay, so this isn't relative to trucks, but it's a similar 8.8 inch rear end.

I'm getting rid of an 88 Thunderbird with a Ford 8.8 inch rear axle... It's a junkyard axle and doesn't whine, so I know it's good, but I'd like to change the oil in it. Especially since it sat in my yard for a while with the driveshaft flange pointing down.

The fill plug is just to the side of the driveshaft and is stuck...

I can drain it by removing the rear cover, but how can I fill it back up again?


Off to the right side (when looking at it from the rear cover) there's a breather. It's on the axle housing, over one of the shafts. If I unscrew it, I can see inside.

Would that be acceptable? I'd just put in according to the manual.

 

try using an impact gun or a breaker bar to free up the filler plug. use some liquid wrench or something like that, let it soak in, then try it.

 

Try what "thehawk" said first. If that dont work, then you are going to have to fill it by other means. I take it that the axle is under the car right?

I wouldnt recommend this for a long term fix, but I have heard that off-roaders would fill a plastic bag up with the recommended ammount of fluid, stuff it in the diff, and then put the cover back on. The gears inside will chew up the bag and release the fluid like normal.

 

I have removed some really stuck ones before, and all I did was get a small bar for leverage and pry away. Only works if the plug isnt stripped though!

 

You could also just tap the cover and put a plug in it and be done. I know the fill on my 9.75 was a bit stuck put with a breaker and cheater bar it broke loose. I have been a big fan of PB blaster lately might try to get some of that on the plug if it will pool and penetrate the threads a bit.

 

My main problem is that I can't get the whole ratchet drive in there. And this is with a nice bendy Mac Tools ratchet.

I'd bet that if I could get the whole drive in there, I might be able to get enough torque on the plug to break it free... Or break off the square drive, whichever comes first.

 

Did you try using an extension on the ratchet? That should give you a better way to get leverage on it also.

 

Impact gun...

 

Hmmm... I suppose I could.

In fact, it just occured to me that I have some wobbly extensions at my parent's house with my 3/8 impact wrench. The wobbly extensions will probably get further into the plug than my ratchet or non wobbly extensions will.

 

Yeah a 3" extension is what is required IIRC, figured you were already using one.

 

Summit Racing sold a plug system that was made to go on a tranny pan for easy fluid changes. The rear diff. covers have to be about the same thickness - so buy one, drill the proper-sized hole at the height of the fill plug, and install Summit's plug.

 

All these are good suggestions, but I have a couple of alternatives if you want to try. If you have to drain the oil anyways, try removing the plug with the cover off. Failing that, call a wrecker and get a diff cover with a working plug and replace the one you have.