View Full Version : Giant Fill Plug on Front Diff.
potts200
10-15-2006, 02:17 PM
Anyone have a tip on removing the giant fill plug on the front differential? Mine looks different from the Haynes manual; it is an 18mm bolt and will not budge. I would hate to round it off or snap it! The Haynes manual shows a small fill plug while mine has a bolt head and then what looks like a giant washer underneath it. The case is a little warm, I drove it about a block in 4 high to get the deposits warmed up so they will drain, so I need to let it cool competely I guess. I soaked it with WD-40. I guess next I will go buy a 18mm socket for a 1/2 inch drive, I was attempting with 3/8. Oh, I have a '02 LTZ w/ 4WD.
MTPockets
10-15-2006, 02:57 PM
Yeah, I've got a post on this from awhile back. Luckily mine came out easily. The gigantic fill plug is machined out of one piece and is fine pipe threaded with a rubber type of seal bonded to the shoulder. I'd keep soaking it with PB Blaster or the likes. Maybe give it a few blows to the face of the hex with a mallet and long socket extension to help break free any oxidation. It's a steel plug, so it will take some abuse if need be.:(
Joel
potts200
10-15-2006, 03:38 PM
Thanks for the tip. Sounds like I might be saving this one for next weekend. I've driven it a few times to central NY a few times during the winter so I know the road salt hasn't helped. I always tried to rinse the undercarriage real well when returing to FL. I have one more question: I just changed the transfer case fluid ( I know, it was a little overdue) and the old fluid that came out was red. The Auto-trak II I put in was blue. Anyone else experience this? It seemed like the case was overfilled also; what a mess! Maybe I should make that question a new thread.
ScarabEpic22
10-15-2006, 04:50 PM
Hmm, I dont remember my front diff plug being hard to get off. The rear plugs, however, were a completely different story. I had to go buy a breaker bar, but then it was like 2 seconds and I had them off.
FYI, if you want to do the transfer case, the drain and fill plugs use a 3/8" hex socket. I dont know what the real name is, but it is a 3/8" hex bolt that goes into the plugs.
If your transfer case fluid was red, I might be worried. The AutoTrak II fluid I drained out of my 02 was dark blue (old fluid with at least 25K on it, probably ~50K) and the new fluid was blue. Red usually means ATF, and these transfer cases dont work with anything but the GM AutoTrak II fluid. If you are in warrenty, I might go complain to the dealer.
LineNoise
10-15-2006, 10:40 PM
Mine came off very easily.
I don't know about the transfer case fluid, I still have to change mine. I'm waiting to goto my buddys shop with a lift.
Bearcat
10-16-2006, 09:55 AM
Red transfer case fluid is a problem. Only fluid specified is Auto Trak II which is blue. Changed mine this weekend at 87K and it was a lot bluer than the first interval at 42K, which turned totally black. Did the rear differential at the same intervals and the Mobil 1 75W90 that came out looked almost new. Went to do the front differential and got the big plug off OK, but rounded the hex on the smaller drain plug. Need to get to the dealer for a replacement before I try to get it off. What a PIA!
potts200
10-16-2006, 11:21 PM
The best explanation I can think of is some newbie at the lube shop I used to go to started draining the transfer case either because he thought it was a service I wanted or because he didn't know better and refilled it without my knowledge with tranny fluid. It seemed to have more than two quarts of fluid in it. I have never used the 4WD extensively so I think it will be okay; the system seemed to work normally after I replaced the fluid. Now I've had the 4WD kick in on me while doing 75 on I-10 but I always considered this a selector switch problem. When it happens some sort of lube vents out and coats the backside of the truck. Maybe that is a result of incorrect fluid or too much fluid.
Bearcat
10-17-2006, 11:17 AM
Maybe that is a result of incorrect fluid or too much fluid.
Shouldn't have been able to add more fluid since it would overflow from the fill port. I think I would use the 4WD on straight and narrow pavement for a few miles off and on, then do another Auto Trak II change to get the tranny fluid off all the surfaces. Then hope for the best. I doubt if they did a fluid swap without charging you for it though.
MTPockets
10-17-2006, 01:17 PM
..I think I would use the 4WD on straight and narrow pavement for a few miles off and on, then do another Auto Trak II change to get the tranny fluid off all the surfaces..
That sounds like a good plan. I wouldn't sweat it too much. I think the 'switch' to auto-trak II came about due to some chatter from the transfer case clutches when run on regular ATF. As long as you had a lube in there & you notice no problems, you should be okay. FWIU, auto-trak II is an overpriced, synthetic ATF that is dyed blue.
Joel