I have a 1994 F150 and the rear differential filler plug won't come out. It has a square hole that a socket extension fits into but the extension slips out before the plug breaks loose. Does anyone know an easy way to loosen the plug?

 

Maybe a little heat.

 

Have you tried digging any dirt/grease out of the hole to make sure the extension is going all the way in?

 

Pound on the end of the extension a little.

 

Breaker bar or an impact. Just don't strip it out.

It'll come out. I had one stuck once and had to take it to a mechanic. I had a breaker bar and it still wouldn't come loose. No impact or I would have tried that first.

 

I used a breaker bar and hit the extention with a hammer but it didn't work. The hole is clean it is just a poorly designed part. I'm thinking about welding a piece of metal to it and then using a pipe wrench but I was hoping there was an easier way.

 

Impact wrench is the way to go...will break it easier than anything else.

Also might want to spray the thread gap with PB blaster and let it sit for a few minutes and try again.

 

Take a straight punch(or chunk of scrap iron) that just fits inside the hole,,use your head,,BUT, give her more than a love tap or three. PB blaster on the threads and tap again TILL it comes loose,,,it will sooner than you think cause this vibrates the rusted threads!! IF you have alot of outside the hole place you can rap there also maybe a hammer over the plug and whap with a 4# hammer on that hammer!!(DONT rivet over the hole) Are you REAL sure you have the RIGHT size extension your sticking in there?? I never saw one that wouldnt come out with soaking and rapping!!