Cavatelli in my Rear Diff

[Zappacoop]

Howdy,

Posting to see if I’m on track or if I should investigate further.

Changed my rear differential gear oil today in my 2004 2500HD Chevy Duramax Pickup.
I loosened the fill plug first, and immediately observed weeping fluid from the fill, suggesting it was overfilled.

I proceeded to drain the fluid. It was used but not spent. Didn’t look bad at All. However at the end, got a lot of this foam like portion. Is the cavitation, a lot of bubbles from being over filled? Or is this a mixture of moisture or something?

I know these are notoriously overfilled. People fill to the fill hole and that’s too much. There was a service bulletin stating that it’s better to be a little under than over.

the bucket the fluid drained into was nasty black before the gear oil went in it. The fluid was not black coming out of the pumpkin.

What do y’all think?

 

[DuckRyder]

Recognizing that its nearly impossible to tell from pictures, that looks like moisture to me.

I guess if it subsides overnight it is foam, if its still milky tomorrow it's probably water. IME water takes a long time to separate (weeks-months-years.)

 

[Sequoiasoon]

I was thinking what would be in rear diff looking like Pasta?

What was the drive time prior? Maybe pour some into a clear container to see if water separates from it.

From Google on Chevron site.
Why is my gear oil foamy?

Insufficient residence times or incorrect oil levels (too much or too little) can also contribute to foaming. Many industrial lubricants are formulated with a foam inhibitor additive, but excess contamination from water, dust, cleaning chemicals, greases or bacteria can compromise the inhibitor.Dec 13, 2021

 

[RDMgr]

The lacy, foamy bubbles on the oil surface in the pail is probably foam. Industrially, foam is often defined as bubbles >1mm in diameter that tend to rise to the surface when the oil is idle where they break if the oil isn’t contaminated with various things and the defoamer is still active. These are obviously that.

The creamy stuff may be emulsified water, sheared polymer if the oil contains VIIs or entrained air. Entrained air tends to remain in the oil mass, bubbles do not readily rise to the surface and they do not break. Entrained air is usually caused by turbulence and churning, a condition that is the norm in a differential, and cavitation.

 

[Dinoburner]

With foam on top of oil isn't it likely air bubbles. Wouldn`t moisture be more uniform in the lubricant?

 

[Ursatdx]

It appears that the entire housing is wet. Perhaps overfilled and leaking from pinion seal.

 

[RDMgr]

With foam on top of oil isn't it likely air bubbles. Wouldn`t moisture be more uniform in the lubricant?

It probably depends on how much water is present an how long the oil has been idle to allow the water or emulsion to separate.

A little of that creamy material heated in a spoon mighty boil if it is an emulsion.

 

[Zappacoop]

Recognizing that its nearly impossible to tell from pictures, that looks like moisture to me.

I guess if it subsides overnight it is foam, if it’s still milky tomorrow it's probably water. IME water takes a long time to separate (weeks-months-years.)

Took a look today - all bubbly cream like substance is gone. The flash makes this look a little weird, it appears like spent oil with no sign of water.

 

[Zappacoop]

It appears that the entire housing is wet. Perhaps overfilled and leaking from pinion seal.

I recently fluid filmed the truck. That and the oozing from the fill hole is what you are seeing.

The rear end was bone dry before I fluid filmed it and has no leaks.

 

[Zappacoop]

With foam on top of oil isn't it likely air bubbles. Wouldn`t moisture be more uniform in the lubricant?

That’s what I was thinking. The foam came at the end.

 

[Zappacoop]

I was thinking what would be in rear diff looking like Pasta?

What was the drive time prior? Maybe pour some into a clear container to see if water separates from it.

From Google on Chevron site.
Why is my gear oil foamy?

Insufficient residence times or incorrect oil levels (too much or too little) can also contribute to foaming. Many industrial lubricants are formulated with a foam inhibitor additive, but excess contamination from water, dust, cleaning chemicals, greases or bacteria can compromise the inhibitor.Dec 13, 2021

haha. I’m glad someone mentioned the pasta in the title haha. I was hungry when I was making this post.

Truck was driven For maybe an hour before this. Engine and transmission were completely up to temp when I drained the rear.

My hypothesis is the last person who changed it out put too much in. They probably filled it until it wept out of the fill hole which is exactly what I would have done if I didn’t do my research ahead of time. This differential case will take more than 4 quarts however it only calls for 3.8.

The 3.8 quarts got me about half an inch below the fill hole from what I can tell with my fancy pinky dip stick.