Frozen fill plug on front diff

[Caesar]

I recently changed the gear oil and diff cover on the rear of my truck and although the fill plug came out, it did have traces of red loctite on the threads. I tried to undo the front fill plug and it won't budge. I only assume that it also has loctite too. Any tricks to getting these loose? We already tried PB blaster and a large breaker bar. I saw something about candle wax around the exposed threads and heating around the plug. Who decided it would be wise to red loctite these plugs should have their head examined, but that is neither here nor there.

If I can't remove the plug what are my options? I have manual hubs on my truck so it doesn't get a lot of use, but I'd like to get the fluid changed without even considering dropping the carrier assembly. Any help would be appreciated...

 

[armadillon]

So the best thing to do is to KEEP getting pb blaster on those threads. I don't know if you sprayed it and then immediately tried, but you should always spray and then wait some hours before trying (some overnight).

Heat always works too, which will require a few hundred degrees of heat to make the metal expand a few thousands of an inch. If you have a buddy, have him keep applying the heat around it as you try to turn it.

You could also try pulling the diff cover and getting pb blaster on it from the opposite side as well.

EDIT: I do see that you've tried both methods, but it WILL work eventually. Worst case you can drill it out and create a new plug by tapping it etc, but use that as a last resort.

 

[Caesar]

Cool man, I know to wait a while after PB blasting it, but multiple applications could help it to penetrate better. About the heat, what needs to be heated and what doesn't? Should I heat around the plug, or just the plug itself? I was hesitant to use heat because I don't know what the carrier assembly (and the plug) are made of and if I can damage or warp it. I have a map gas torch so that should do the trick. Removing the cover on the front is near impossible without dropping the whole axle I believe. I'd like to get it back on a lift, although I did the rear on the ground.

 

[ab_slack]

If it has Loctite on it, I don't know that PB Blaster will do anything to it.

With heat I generally consider it best to heat the nut rather than bolt, in this case that would be the housing. The rationale is that heating the nut will expand it making it loser while heating the bolt/plug will make the bolt tighter.

Heat is not just about expanding metal to make it looser though. It does shift things dimensionally and will break corrosion and cause it to release. So even if you have to heat the whole area, it is going to help.

In the case of Loctite, heat will break down the Loctite and burn it off so heating the plug may be the best.

So how's that for a yes maybe it could be better either way answer?

Before you heat, I expect it be best to drain the fluid first. Since the TTB is like the cover, I don't think there is anything sensitive right by the plug. The only thing I would really be concerned about heating would be the reaction of oil on the inside.

Other thing is a bigger lever.

 

[Die.Fledermaus]

You can't remove the cover on that, besides I wouldn't drain it without a fill method in mind.

I like both the heat and leverage methods. With loctite properly installed one is supposed to cook it off, before attempting to turn it.

And lately on my NPT fillers and drains I have been using one wrap of teflon tape on reinstall and I do find it nicer than dry.

 

[Caesar]

Yes, all good input! I am sure I will manage to get the plug out without having to drop the diff and the cover. I have access to my father in laws shop on the weekend so I can get it on a lift and do a 2 man operation. I'll report back with an update this weekend hopefully.

 

[4x4junkie]

Heat is what is used to loosen the bond of red Loctite. Heat the area around the plug to around 250-300°F with a propane or MAPP torch and it should come out (300° shouldn't damage anything inside the diff).

Before you heat, I expect it be best to drain the fluid first. Since the TTB is like the cover, I don't think there is anything sensitive right by the plug. The only thing I would really be concerned about heating would be the reaction of oil on the inside.

How would he drain it unless by some chance the PO added a drain plug to it... ?

Maybe park the truck nose-up on a steep hill so the oil inside flows back & away from the area being heated.

 

[Caesar]

Well since the fill plug is also the drain plug the oil should be below it. For all I know the oil could be low too, and that is precisely why I'd like to change the fluid. The truck has 130,000 on it and the front axle isn't live. What adverse effects could the heat (300 degrees or so) have on the oil? It is cold here in NE so warming it up a little might make it easier to evacuate with a suction pump afterwards.

I will be liberal with the heat and try to focus it mainly around the edge of the plug to break the loctite like suggested. I certainly won't heat it until the oil starts to boil off. The plug is on the drivers side right next to the axle shaft extension for the CV. The closest oil seal is at the rear pinion where it connects to the front driveshaft. I will keep heat away from that seal for sure. Thanks for the tips and suggestions guys!!

 

[racsan]

the first time i removed my front diff plug it was extemely tight also, how i got it loose was to have a big beefy cresent wrench on it, with a small bottle jack up against the end of the cresent wrench, it did work though. once it was out i coated the threads with antiseize.