Rear diff vent tube has a rough hole in it

[6716]

So I stripped out the fill plug, there's no way that is coming out. So, I figured I would try the vent tube for refilling. About 6 inches up from the diff, the tube has a hole in it that looks like something chewed through it. It is cut about half way through.

Not a huge issue, and actually it kinda makes it easier to refill this way.

But I don't find the replacement tube on Rockauto or for sale anywhere. Maybe I am going to have to go to the dealer on that one.

 

[Mooseman]

Should be able to get a length of vacuum hose at the parts store. That's basically what it is. Or some fuel line.

For future reference, I would have gotten an aftermarket cover with a fill plug. Much faster filling

 

[6716]

For future reference, I would have gotten an aftermarket cover with a fill plug. Much faster filling

I still could. But the only ones I find are like $200 before shipping.

 

[NJTB]

I was looking for the same thing, wanted the fill plug in the cover. A member here suggested going to Purple Cranium. They have them for a lot less than $200.

 

[Mooseman]

Damn, that's right. The 8" aren't plentiful for covers. There is the tranny drain plug add-on that could work. Not the biggest hole but better that the tiny vent.

Dorman HELP! 65128 Transmission Drain Plug Kit, Oil Drain Plugs - Amazon Canada

Dorman HELP! 65128 Transmission Drain Plug Kit in Oil Drain Plugs.

www.amazon.ca

 

[6716]

I was looking for the same thing, wanted the fill plug in the cover. A member here suggested going to Purple Cranium. They have them for a lot less than $200.

Thanks for that tip. No plug in the covers from that vendor for a 2005 Trailblazer. At least according to their site that I could see.

Damn, that's right. The 8" aren't plentiful for covers. There is the tranny drain plug add-on that could work. Not the biggest hole but better that the tiny vent.

Dorman HELP! 65128 Transmission Drain Plug Kit, Oil Drain Plugs - Amazon Canada

Dorman HELP! 65128 Transmission Drain Plug Kit in Oil Drain Plugs.

www.amazon.ca

I was trying to think how I could do some custom thing. I think the challenge with that Dorman part is -- how do you keep the inside one in place while filling? You'd have to JBweld or something. That little hack definitely works better for draining on a horizontal surface than filling on a vertical. With my luck I would get it full and the inside one would fall down in.

Anyhow, I don't think the vent thing is going to be so bad. I am replacing the hose anyway, so I may as well take it off from the diff before I fill, AND the hole/extension on the diff is not actually all that small AND the fill bottle does have kind of the tapered nipple end ... so I predict it will not be so bad when I get to it after work today.

Certainly it is all a lot easier to move around right there with the spare down.

 

[Mooseman]

how do you keep the inside one in place while filling?

You don't need to. You only remove the centre plug, which is like 5/16" (I think it's a 1/8NPT plug). You'd hold the outer bolt with a wrench while you remove the plug.

Another option would be to weld a nut onto the cover and use an engine oil drain plug.

 

[6716]

Another option would be to weld a nut onto the cover and use an engine oil drain plug.

I considered that as well. I am not a welder, and I don't know one. Google says there might be a couple of welding shops nearby. Maybe I will check with them. They might be good to know in general.

Also I didn't look at the second picture of that Dorman part at first. Now I see that it looks like the outer and inner nuts thread together. What are the chances the inner part would not clear any of the moving parts of the diff in there I wonder.

 

[Mooseman]

I wouldn't put it right on the ring gear hump. Off to one side of it or the other would probably work fine. I'd probably go just to the right where there is a void/

However, I just happen to find this post that explains that apparently you CAN use the 8.6 cover on the 8.0 diff. You'll just have to add extra fluid.

Differential cover, bolts and gasket for 8-inch rear end

There have been many posts asking about the rear diff cover, so I thought I would just address some of the questions in one new post based on recent experience. Aftermarket rear diff covers for the 8-inch rear end that comes on most short-wheelbase 4.2-litre Trailblazers and Envoys seem to be in...

gmtnation.com

 

[6716]

Now that I have the diff cover off i see what you mean about the hump. The dorman should work.

What does this magnet tell me? There's a good ridge down the middle

 

[Mooseman]

If it's just black sludge, it's fine. That's normal wear. If there are silvery metal chunks, that's not normal.

 

[6716]

Whether you are filling via the vent tube or fill plug ... both methods are faster when you remember to take the seal off the replacement fluid bottle

 

[6716]

Well I guess that went OK. No leaks. New gasket.

I ended up re-using the remaining vent tube. I took about 6 inches off to remove where it was torn, and it didn't quite reach the clip I took it out of. So I just ran it straight up through/into two openings in the body. I think it is supposed to be like a snorkel, so water doesn't get into the diff via the vent tube, so I figured if it goes staight up and ends up a couple of inches higher than the clip it probably will work as intended.

For the NEXT fluid change I think I will be ready with the diff cover with the fill plug in it.