Rear diff cover with a sight glass.

[Shannonwilkerson]

hey guys, made an oopsie today. Not proud of it but I’ve learned from it and I hope some of this could help you guys out.

Got in my truck to go to town and get some gas for the mower and a few other small things and when I got to town and turned in to my local ethanol-free gas station, noticed the rear differential was “grabbing”, like a clunk-clunck-clunck.

It did it again turning out and getting back on the road, but when I’m going straight down the highway it was smooth as silk, no whine on acceleration or deceleration.

Thought to myself “wonder if the g80 is giving up the ghost”

Got home and checked the gear oil. It was low. Turns out it was two and a half quarts low.
Topped it up and drove it, it stopped doing what it was doing. All is well.

I normally check everything with every oil change. Grease the front end and ujoints every other oil change. Very particular about my vehicles maintenance. My close friend, who is also a gearhead tells me i waste money on over-maintaining.

Shoot…my lawn mower gets plugs, oil change, new blades, fuel filter, and the belts get checked every fall….

Anyways the point is, it happens to the best of us and it looks like I’m going to be doing axle/hub seals and a full service on this thing soon.

Can you guys recommend a diff cover with a sight glass or could I add one to my stock cover? I’ve seen a few on various vehicles and it would be great if I could peep under there every so often and go “yep..she’s good” without having to pull a fill plug?

Vehicle in question: 2000 GMC C3500 sierra SLT 7.4/4l80e with the gm 14 bolt 10.5” rear axle.

 

[D60]

I've only ever seen the one Banks built, and I've seen high zoot aftermarket t-cases with sight tubes.

Most guys wouldn't want it for durability reasons. I'd rather back into a rock with a steel cover.

You might consider just checking it every other oil change, or you could get creative and build a dipstick for it -- drill and tap the top of the housing somewhere and make or buy the actual dipstick.

A sight tube on the side of the pinion snout could be really cool and less vulnerable? But I think you'd need to drill two holes for either end of the tube. Here's a kit for a D300 t-case
https://taboocustoms.com/store/D300sightglasskit

 

[AZjeff]

OP said sight glass, a little round glass window, not a sight tube.

Here's one on Amazon: sight glass
Weld a 3/4 NPT female thread on the cover.

 

[Lubener]

I would be more concerned where did the oil go? I doubt it was filled being 2 1/2 quarts low.

The way I see it , having to slide underneath to view the sight glass , why not just go one step further and remove the plug to check the gear oil. I don't see it being a big deal.

Many plugs are magnetic to attract wear metals and I would rather have that than a sight glass incorporated in the plug.

 

[Shannonwilkerson]

I would be more concerned where did the oil go? I doubt it was filled being 2 1/2 quarts low.

Leaky axle seal on passenger side. I checked it about a month ago and everything was dry.

 

[Lubener]

Leaky axle seal on passenger side. I checked it about a month ago and everything was dry.

View attachment 273933

Time to reseal that axle. That would be my priority. The linings are likely ruined too.

 

[Shannonwilkerson]

Time to reseal that axle. That would be my priority. The linings are likely ruined too.

That’s the next thing on the chopping block. It’s already going to be down for a set of injectors and a fuel pressure regulator, so I have all of the brake hardware/shoes/wheel cylinders on the way as well.

 

[PontiacHO]

hey guys, made an oopsie today. Not proud of it but I’ve learned from it and I hope some of this could help you guys out.

Got in my truck to go to town and get some gas for the mower and a few other small things and when I got to town and turned in to my local ethanol-free gas station, noticed the rear differential was “grabbing”, like a clunk-clunck-clunck.

It did it again turning out and getting back on the road, but when I’m going straight down the highway it was smooth as silk, no whine on acceleration or deceleration.

Thought to myself “wonder if the g80 is giving up the ghost”

Got home and checked the gear oil. It was low. Turns out it was two and a half quarts low.
Topped it up and drove it, it stopped doing what it was doing. All is well.

I normally check everything with every oil change. Grease the front end and ujoints every other oil change. Very particular about my vehicles maintenance. My close friend, who is also a gearhead tells me i waste money on over-maintaining.

Shoot…my lawn mower gets plugs, oil change, new blades, fuel filter, and the belts get checked every fall….

Anyways the point is, it happens to the best of us and it looks like I’m going to be doing axle/hub seals and a full service on this thing soon.

Can you guys recommend a diff cover with a sight glass or could I add one to my stock cover? I’ve seen a few on various vehicles and it would be great if I could peep under there every so often and go “yep..she’s good” without having to pull a fill plug?

Vehicle in question: 2000 GMC C3500 sierra SLT 7.4/4l80e with the gm 14 bolt 10.5” rear axle.

There is a leak. Typically it can be seen and/or smelled way before it’s ran dry. 2.5 qts was totally empty. Differentials don’t use or burn oil. They are not consuming anything. They are not internal combustion engines. They do leak. If you crawl under to inspect a “sight glass” you can also look for leaks. Pinion seal, axle seals, and rear cover gaskets leak leaving an obvious oily mess.

 

[rijndael]

Got home and checked the gear oil. It was low. Turns out it was two and a half quarts low.
Topped it up and drove it, it stopped doing what it was doing. All is well.

I recently saw an F150 nearly 2 quarts low and I topped it off to keep him going. It didn't make a noise. The cover was pulled a couple of weeks later and it was loaded with metal/glitter.

Pulling the cover for a full inspection should be the next step, rather than focusing on a sight glass. If it's good, then focus on fixing the leak.

 

[Jdeere562]

Sight glass can be misleading. One like AZjeff posted might be better than my experience.

I used to work on Allis Chalmers tractors in the 70's and 80's. They used sight glasses for the differential and hydraulics at the rear end.
After time they got a coating from the tan looking oil. Looked like they were full, but they were not. Had to unscrew the glasses and clean them. That was kind of embarrassing to the farmer. Pay for a service call because of cavitating hydraulics, just to have me unscrew
the glasses and clean them.

 

[thastinger]

Leaky axle seal on passenger side. I checked it about a month ago and everything was dry.

View attachment 273933

Wow...I'd say that drum is about as big as it could possibly be with that wheel.

 

[crashz]

If I remember right, there was once a company that produced a poly carbonate diff cover for off roaders. Was meant to look cool, as it had no practical use and was more fragile than steel. I think they also learned that churning gear oil is not sexy.

Fortunately being a 14 bolt, you still had some oil in there. About a quart if I remember right. And its a sturdy axle. Doubt you did any major damage to it.

I would suggest checking the bearings closely on the leaky side. That would have seen the majority of wear due to lack of lube.

 

[D60]

Sight glass can be misleading. One like AZjeff posted might be better than my experience.

I used to work on Allis Chalmers tractors in the 70's and 80's. They used sight glasses for the differential and hydraulics at the rear end.
After time they got a coating from the tan looking oil. Looked like they were full, but they were not. Had to unscrew the glasses and clean them. That was kind of embarrassing to the farmer. Pay for a service call because of cavitating hydraulics, just to have me unscrew
the glasses and clean them.

Agreed, which is why I was thinking a tube. Sight glasses are more difficult to read and would require a large (but single) hole to install. A tube is easier to read and requires two (smaller) holes.

I can't read the glass on my Kubota at all. I've been meaning to try the JD dye that is supposed to make it easier to differentiate the fluid from the brown glass. No idea if it works.

 

[SwampSurvivor]

I would be more concerned where did the oil go? I doubt it was filled being 2 1/2 quarts low.

The way I see it , having to slide underneath to view the sight glass , why not just go one step further and remove the plug to check the gear oil. I don't see it being a big deal.

Many plugs are magnetic to attract wear metals and I would rather have that than a sight glass incorporated in the plug.

I swapped the rear axle in my car last year. Filled 2 spill on the fill plug. Drove it 5000 miles and it was down almost a whole quart. No signs of leaks out of the axle seals or pinion seal. I had the brakes off a few times doing the parking brake so I would have noticed if it was coming out of the axle seals. I had to pull the driveshaft during that time too, pinion was dry. No idea where it went.

Checked it last week, 7000 miles since I topped it off and it's completely full.