Rear Differential Fluid Change.

47793 Views 18 Replies 5 Participants Last post by stchman, Jun 12, 2013

stchman

Discussion Starter · Jun 10, 2013

Changed the fluid in the rear differential. The amount of fluid that I removed was ~2.25 quarts, and the fluid I put back in was ~3.25 quarts. I put fluid in until it ran out the fill plug. I wonder why the difference?

Used Mobil 1 75W-90 gear oil.

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steved

· #3 · Jun 10, 2013

j cat said:
since you drained out A QT less then you must have a leak. check the fluid every oil change for level and fluid color.

Could be as simple as the position of the asymmetrical center section...turn it one way and it will displace more volume than if its turned 90*. Depending on its position when it was last filled...

A leak on a differential should show up pretty readily. Even an ounce will make a complete mess underneath a truck; let alone a quart.

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steved

· #5 · Jun 10, 2013

I want to say mine was "low" by my standards when I brought it home...it was around a 1/2 inch (or more) below the fill hole. I'm thinking they probably fill them by volume (automated, so to speak), and not by level...I fill this one to where the fluid runs out the fill hole.

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steved

· #7 · Jun 10, 2013

I have a 10.5", and I want to remember the 10.5" is "level with the fill hole"; but I do know it depends on the differential.

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steved

· #9 · Jun 10, 2013

stchman said:
You must have a 2500 Silverado.

I was under the impression that the 2500 and 3500 rear differentials were made by Dana while the 1500 diffs were made by Eaton.

The only Dana I know that GM used in a rear application was the Dana 60 in some of the 3/4 ton vans a while back. Until they switched to IFS, they used the D44 (later replaced by the Corp 10-bolt) and D60 for the front axle.

This 10.5 is what i know as a "Corporate 14-bolt", and its design has been in use by GM since the late 60s/early 70s.

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steved

· #11 · Jun 10, 2013

stchman said:
Before this thread gets too far off topic:

I would like the opinion of some of the forum members as do they think that filling G80 8.6" differential on a 2013 SIlverado up to the fill plug is bad, good, does not matter?

Thanks.

The only thing I could see happening is if it was overfull it would aerate and foam...

However, the way a differential lubrication system works is that the ring gear slings the lubricant up into the front of the housing to flood the pinion bearings. So if its a little over filled, its not going to know the difference (think about running on a side hill, up or down a steep hill, etc...the level is always changing anyway.

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steved

· #14 · Jun 10, 2013

Yes, the venting would prevent pressure buildup.

FWIW, I ran the 11.50AAM in my Dodge (same thing under a Duramax) with an ORU cover that placed the fill port 1.5 inches higher...I ran with the fluid that much high, in an 85w140 blend for 150k miles, then switched to a 75w140 for another 50k. I never had a dribble.

The AAMs are a very good axle...

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steved

· #18 · Jun 12, 2013

RayVoy said:
I have not been able to find the correct volume of fluid; however, the level should be between 1/2" below the hole, to the bottom of the hole (truck level).
In other words, if checking and the level is no lower than 1/2" below the hole, the level is good. If filling, or topping up, the fluid should be added until it drips out of the fill hole.

From the 2012 OM:

To get an accurate reading, the
vehicle should be on a level
surface.

For all 4.3 L, 4.8 L and 5.3 L
1500 Series applications, the
proper level is 1.0mm to
19.0mm (0.04 in to 0.7 in)
below the bottom of the fill hole,
located on the rear axle.
Add only enough fluid to reach
the proper level.

For all 6.0 L and 6.2 L
1500 Series applications, the
proper level is from 15mm to
40mm (0.6 in to 1.6 in) below
the bottom of the fill plug hole,
located on the rear axle.
Add only enough fluid to reach
the proper level.

For all 6.0 L 2500HD Series
applications, the proper level is
from 0mm to 13mm (0 to 0.5 in)
below the bottom of the fill plug
hole, located on the rear axle.
Add only enough fluid to reach
the proper level.

For all 6.6 L Duramax Diesel
2500HD Series applications and
all 3500 Series applications,
the proper level is from 17mm
to 21mm (0.6 in to 0.8 in) below
the bottom of the fill plug hole,
located on the rear axle.
Add only enough fluid to reach
the proper level.

Interesting enough:

All axle assemblies are filled by
volume of fluid during production.
They are not filled to reach a certain
level. When checking the fluid level
on any axle, variations in the
readings can be caused by factory
fill differences between the minimum
and the maximum fluid volume.

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