Dodge Ram Diesel Dana 70U with 437k Miles

[JHZR2]

Just changed the oil in my 96 Ram 2500 Cummins Turbo Diesel. It is a 3.55 Dana 70U, and apparently an LSD (didn’t see that on the build sheet).

Everything was pretty black in there, but the gears looked fine. Lots of sludge picked up on the magnet.

Cleaned up with gasoline, in order to help remove old RTV. FSM also asks to flush some new oil through the diff to remove more of the dirt in there.

Replaced with 2.8 quarts, and will add 0.4 of LSD additive per the FSM.

Now good for another few hundred thousand miles!

 

[JC1]

When was the last fluid change? Looks good to me, have you owned this since 98?

 

[wpod]

How many miles on that oil? That is metal on the magnet and not sludge.

 

[JHZR2]

When was the last fluid change? Looks good to me, have you owned this since 98?

Unknown duration since the last change, I have not owned it since new. I am the third owner.

How many miles on that oil? That is metal on the magnet and not sludge.

Agree it is metallic, otherwise it wouldn’t stick. It is ultra fine and gelatinous...

 

[oldhp]

Differentials are funny. Either they last 5K miles or 500K miles.

 

[doublebase]

How many miles on that oil? That is metal on the magnet and not sludge.

True, but if that fluid hasn’t been changed in 200,000 miles or so?? That is probably what you’d expect on that magnet. It’s fine metal dust, which is what you’d expect on a differential magnet. If it were bigger pieces I’d be worried...but I think we’re just looking at a differential with obviously a ton of mileage and a very long interval without being serviced. But I always see something on a differential magnet, it looks just like this but obviously way way less accumulation.

 

[SatinSilver]

Are the miles in the thread title correct? I thought this truck was an older low mile unit based on a previous thread.

 

[JHZR2]

Are the miles in the thread title correct? I thought this truck was an older low mile unit based on a previous thread.

Yes they are correct. Ended up buying a different truck with a great bed that’s very useful for me. High mileage but great deal and runs perfect. With a rebuilt AT already done.

Only thing it needs now is an upper ball joint.

 

[supton]

That sludge was almost pretty looking... in a bad way.

I'm guessing you're not going to daily drive this and take to the other side of a million miles. I would oil up and motor on, just like you've done. Whatever damage exists is done, might as well see how long it lasts.

 

[JHZR2]

I doubt there is any damage... There's wear and fluid degradation, but no sparkly materials in the fluid itself. I suspect the metal and the black stuff is from the LSD clutch packs. There is no noise or whine, or clunkiness, from the diff. Im sure this thing will go for another million miles... The teeth look great.

 

[Rhymingmechanic]

Looks like it was time for a change. Job well done.

Does this unit have a drain plug? If so, it could have been changed that way before without the magnet getting cleaned.

What's with the rounded gear teeth behind the ring gear? I've never seen that before.

 

[slacktide_bitog]

Yuck! Good thing you changed it!

 

[Nick1994]

How’s the front diff?

 

[JHZR2]

Looks like it was time for a change. Job well done.

Does this unit have a drain plug? If so, it could have been changed that way before without the magnet getting cleaned.

What's with the rounded gear teeth behind the ring gear? I've never seen that before.

I think the round teeth are for the speedometer. May be wrong there.

No drain plug...

How’s the front diff?

2WD

 

[supton]

What's with the rounded gear teeth behind the ring gear? I've never seen that before.

ABS tone ring? For a single channel to the rear, maybe. Might not be used here but perhaps ABS was an option and thus this tone ring was added to all axles (or this was swapped in), certainly could be used for speed detection also.

 

[Snagglefoot]

Interesting. If you look closely at the stuff scraped off in the 7th photograph you can see a few spikey chards, much like the chards on my Chevy 14 bolt. Also, the magnet position is interesting, not being on the bottom. I guess it doesn’t matter as the fluid is getting thrashed around. My photo shows the chards being displaced upward after I pushed my finger into the middle of the magnet.

 

[JHZR2]

ABS tone ring? For a single channel to the rear, maybe. Might not be used here but perhaps ABS was an option and thus this tone ring was added to all axles (or this was swapped in), certainly could be used for speed detection also.

This truck has rear wheel abs only. But how can one differentiate the lockup of one or two wheels with just one ring? That would only indicate if both wheels are locked. Not aware if the system can work like that...

 

[supton]

Let's see, when doing a burnout, one wheel stuck, the other winds up spinning twice as fast, right? Open diff that is. Thus at a given speed, if one wheel locks up, the driveshaft would be spinning half as fast, no? Even if I'm off, the sudden change in driveshaft speed could be used to determine the issue.

But I suspect they didn't care if one locked up, only if both did, since that would very easily lend to swapping ends. One locked, yeah it can be easier to lose control, but I'm also guessing that locking up only one rear was determined to be a low probability event. In the end, this was cost cutting at its best--let's put out a halfway solution, hope for the best. As we can see, it didn't last long.

 

[slacktide_bitog]

Nice pictures! Thank you for posting

Too bad your diff doesn't have a drain plug

 

[mattd]

This truck has rear wheel abs only. But how can one differentiate the lockup of one or two wheels with just one ring? That would only indicate if both wheels are locked. Not aware if the system can work like that...

The tone ring is on the carrier. The power split between the wheels is controlled by the spider gears