Chevy & GMC Vans

I was planning on changing the differential fluid today (something I haven't done since owning the van) But I went to remove the fill plug and I could not. Now it looks like it is just a 3/8" square cap screw. Do I need to buy a square drive socket, or could I just use a 3/8" extension? I tried using just the extension but it didn't want to budge. Haven't tried a torch yet -don't want to either honestly.

I'm thinking if it gives me too much trouble, I'll just throw down some change and get a new differential cover with the fill plug on it. So is there a trick to getting it off? What would you do? Thanks in advance..

Steve O

The plug is a 3/8" square drive. I use a 6" extension that actually twists when I try to remove it. If you can't get it, use heat! Many have to do that.

I use my 1/2 inch impact with a 1/2 to 3/8 adapter. Slow light bursts.

Got advice on the diff plug.

I want to top off or change the diff fluid on my 2003 AWD. I uses a different type oil in the front diff and a different in the rear and it uses the GM special stuff in transfer case. to change it I guess I can siphon out most from the fill hole instead of pulling the cover?

I will get my air impact ready if the plugs are stuck but I think the weather has warmed a bit and should come out OK on the 2003.

Astrophysics

Thanks for the responses guys. My main concern was whether I had to buy a special square socket, because when I was using the extension, it didn't feel like it was seating all the way in the plug. I thought it might be because of the check ball on the side of the extension.
While the impact wrench would be a good suggestion, I live in an apartment, and it is a PITA to move my 33 gal compressor up and down the stairs to my van. Looks like I'll be breaking out the torch after all.

Astrophysics, I have heard of people just siphoning out all the old fluid thru the fill hole and replacing it with fresh fluid, but I personally think it's better to pull the cover when changing fluid. That way you can check the gears for any abnormal wear, broken teeth and such.

gotta pull the cover and inspect. Don't skimp there. Plus, it's an easy reseal. I'm surprised the plug is giving you trouble. If you're going to remove the cover, forget the plug altogether, but plan for a larger catch can. ;-)

LiftedAWDAstro wrote:The plug is a 3/8" square drive. I use a 6" extension that actually twists when I try to remove it. If you can't get it, use heat! Many have to do that.

I remember the problems PJ had up at your place,and the little blue propane tortch didn't give enough heat,we had to go pick up your buddies torches, and finally it came out.Remember to slap some anti-seize on the plug if/when you get it out.

Definitely want to remove the cover to inspect & pull out the old sludgy fluid from the bottom...that stuff stinks ,LOL

astrozam wrote: Definitely want to remove the cover to inspect & pull out the old sludgy fluid from the bottom...that stuff stinks ,LOL

you're not kidding! that stuff reeks. even the synthetic stuff smells

on a lighter note, when i did seals and brakes on the back of my 88 s10 years back, i actually could not get the fill plug removed. i wound up measuring out the amount of fluid and filling the axle through the vent hose.

im going to try the impact gun trick next time i have my van at work , i tried by hand and it wont budge.

Well, I am certainly glad to see that I'm not the only one with this problem!! I'm going to try the propane torch later today or sometime this weekend. Hopefully it will be enough.

On the subject of how nasty the fluid is, you think it smells bad, try tasting it sometime!!
Several years ago, we got a vehicle in that was just abused from mudding. The rear end was completely shot. As I was dissasembling it, my boss dared me to lick the inside of the cover. Being young, stupid, and broke, We settled on a price, 5 whole dollars, and I licked the cover. No I didn't swallow!!! The worst part about it? had I waited another minute, he was going to raise the amount to 20 bucks!

What can I say, I'm a sucker for a good dare...

I had the same problem on my 88 Astro last year. Spray PB Blaster on the plug every day for 5 days. After you spray take a round pin punch, put it inside the 3/8 square and tap the punch lightly with a hammer. After 5 days try to remove the plug and it will turn.

For the life of me I don't understand why some people think that plug needs 900ft lbs of torque. It's a pipe thread and all it needs is a snug. The propane torch won't generate enough heat. You need an oxy-acetelene torch. And heat around the plug, not directly on it. And while you're at it remove the cover. There's a lot of sludge in there that needs to be cleaned out. And maybe a magnet that collects all of the metal pieces. There's no point in doing the job if you're not going to do it right.

SUCCESS!!!! I got the fill plug out today, and without the use of heat. I don't know why I didn't think of it before My son had been messin' with my tools yesterday, when he pulled out the 36" breaker bar and started swinging it around like a bat. This morning I grabbed my 1/2" to 3/8" adapter along with the breaker bar. The plug came loose within a couple seconds. Unfortunately I have to go to work now, so the fluid change will have to wait till another day, but at least I know the plug isn't going to be a problem now.

astronut74 wrote:...my boss dared me to lick the inside of the cover. Being young, stupid, and broke, We settled on a price, 5 whole dollars, and I licked the cover. ...What can I say, I'm a sucker for a good dare...

Well, I doubt that anyone around here can say anything bad about your dare--we've all done crazy things.
I seem to remember that Peter once managed to extinguish a lit cigarette held in his mouth by splashing his face with gasoline.
Me? I managed to run over myself, from feet to head, with the vehicle I was driving back when I was 18. That trick sure made the deputy sheriff laugh out loud in the hospital emergency room when he asked if I wanted to press charges against the driver.
But we all came through our lapses of reason okay. But we all came through our lapses of reason okay. But we all came through our lapses of reason okay. But we all came through our lapses of reason okay. But we all came through our lapses of reason okay. But we all came through our lapses of reason okay. But we all came through our lapses of reason okay.
brzzzzp aDjusT mE brzzzzp adjUst Me brzzzzp AdjuSt ME...

FUNNY, Rob!!!!!!!!!!!!!!!!!!!!!!!!!