I have searched the forums and found topics of thick sludge in the diff, but it's usually associated with 4 wheeling in high water. I drive a rear wheel drive dodge dakota and NEVER go through water. I had drained the stinky dino gear oil when I got the truck with 120,000 miles and refilled with valvoline synthetic 75-90, at the time I had cleaned out the bottom of the diff and refilled. Now at 170,000 I once again drained the fluid and the goop is in there once again. Is this normal? I never tow or drive hard and stay off of dirt roads. I hosed everything down with brake cleaner and refilling with castrol synthetic. Is there anything I should do to help keep the differential running cleaner and not having this sludge left behind? The fluid drained out perfectly clean so obviously the sludge does not stay suspended in the gear fluid. It's possible the valvoline mixed with the old dino residue to make this sludge, but still if there is a way to keep everything clean I sure would like to know!!!
thick sludge in bottom of differential
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MolaKule
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Quote:
It's possible the valvoline mixed with the old dino residue to make this sludge, but still if there is a way to keep everything clean I sure would like to know!!!
The new gear lube must be suspending the old sludge it has picked up.
Recommend changing out and wiping old sludge until no more sludge is found.
Some people never change fluid at periodic intervals and this is what can happen.
It's possible the valvoline mixed with the old dino residue to make this sludge, but still if there is a way to keep everything clean I sure would like to know!!!
The new gear lube must be suspending the old sludge it has picked up.
Recommend changing out and wiping old sludge until no more sludge is found.
Some people never change fluid at periodic intervals and this is what can happen.
I am not sure that hosing the inside of the diff with brake cleaner isn't part of the problem. The wrong solvent can cause issues.
I would do what Molakule recommended.....A couple of short change intervals, until the amalgam is no longer evident.
I would do what Molakule recommended.....A couple of short change intervals, until the amalgam is no longer evident.
A mechanic that converts police Crown Vic's to taxis told me that he thinks most police departments never change the diff fluid. He said that he has a hard time on some, getting them cleaned out and ready for new gear oil. This means that many of these CV's go 80-120K on the factory fill before he gets them. And a diff failure in taxi service is almost unheard of, he's never seen one.
Originally Posted By: mech_tech
.The fluid drained out perfectly clean so obviously the sludge does not stay suspended in the gear fluid. .
If that sludge settles to the bottom, and even if a small chunk gets up into the gears, I don't see any damage happening. It does depend on how much though cuz cooling (heat transfer) might suffer a little.
.The fluid drained out perfectly clean so obviously the sludge does not stay suspended in the gear fluid. .
If that sludge settles to the bottom, and even if a small chunk gets up into the gears, I don't see any damage happening. It does depend on how much though cuz cooling (heat transfer) might suffer a little.
Originally Posted By: mech_tech
The differential is open without limited slip...just gears, oil, and gray goop in there. The magnet hardly had any metal particles on it...just the slimy goo.
That really does sound like water. I had a car that I drove through axle deep water once. It took 3 diff fluid changes for the frothy stuff to finally go away. I think the water gets trapped in the bottom, and doesn't evaporate like you would think.
A couple of short change intervals should straighten that out.
The differential is open without limited slip...just gears, oil, and gray goop in there. The magnet hardly had any metal particles on it...just the slimy goo.
That really does sound like water. I had a car that I drove through axle deep water once. It took 3 diff fluid changes for the frothy stuff to finally go away. I think the water gets trapped in the bottom, and doesn't evaporate like you would think.
A couple of short change intervals should straighten that out.
Nick1994
$100 site donor 2024
Originally Posted By: mech_tech
The differential is open without limited slip...just gears, oil, and gray goop in there. The magnet hardly had any metal particles on it...just the slimy goo.
The Trac-Lock rearend has spider gears and looks like an open differential. There should be a tag on the differential cover and if it has LS on it then it's a limited slip trac-lock.
I don't see it being clutch material, the clutch packs are really small and thin, not a lot to wear off unless they were broken and then you'd probably know.
The differential is open without limited slip...just gears, oil, and gray goop in there. The magnet hardly had any metal particles on it...just the slimy goo.
The Trac-Lock rearend has spider gears and looks like an open differential. There should be a tag on the differential cover and if it has LS on it then it's a limited slip trac-lock.
I don't see it being clutch material, the clutch packs are really small and thin, not a lot to wear off unless they were broken and then you'd probably know.
A rag and some non-chlorinated brake cleaner is all you need.
Sorry to hijack post. But this moisture talk got me thinking.
What is a normal diff temp? I am sure there are many variables that affect it.
Do they get hot enough to burn of any trapped moisture/water?
To be honest, as a state/ase cert diesel and petrol mechanic I am embarrassed not knowing.
Harvey
What is a normal diff temp? I am sure there are many variables that affect it.
Do they get hot enough to burn of any trapped moisture/water?
To be honest, as a state/ase cert diesel and petrol mechanic I am embarrassed not knowing.
Harvey
Originally Posted By: JR
Sorry to hijack post. But this moisture talk got me thinking.
What is a normal diff temp? I am sure there are many variables that affect it.
Do they get hot enough to burn of any trapped moisture/water?
To be honest, as a state/ase cert diesel and petrol mechanic I am embarrassed not knowing.
Harvey
Yes, they get hot enough.....But.....They are not vented well, so the water just turns vapor, and sticks around. Only to cool later, back into the fluid. So.....Even though it evaporates, it has no where to go.
Sorry to hijack post. But this moisture talk got me thinking.
What is a normal diff temp? I am sure there are many variables that affect it.
Do they get hot enough to burn of any trapped moisture/water?
To be honest, as a state/ase cert diesel and petrol mechanic I am embarrassed not knowing.
Harvey
Yes, they get hot enough.....But.....They are not vented well, so the water just turns vapor, and sticks around. Only to cool later, back into the fluid. So.....Even though it evaporates, it has no where to go.
Nick1994
$100 site donor 2024
Is it possible the vent tube is broken and driving through the rain gets water up in there?
Originally Posted By: JR
What is a normal diff temp? I am sure there are many variables that affect it .
A Finnish built 75 tonner differential measures 58 - 66 C with SAE 140;
Whilst a NA built measures 77-88 C with 80W-90.
Ambient is 33ish C.
What is a normal diff temp? I am sure there are many variables that affect it .
A Finnish built 75 tonner differential measures 58 - 66 C with SAE 140;
Whilst a NA built measures 77-88 C with 80W-90.
Ambient is 33ish C.
Originally Posted By: DemoFly
A rag and some non-chlorinated brake cleaner is all you need.
+1
This is why I prefer removing a diff cover instead of removing a drain plug.
If the differential oil can only be changed by pulling a drain plug, I like to drain the factory fill early, run a cheap gear oil for a short interval, then use premium gear oil.
A rag and some non-chlorinated brake cleaner is all you need.
+1
This is why I prefer removing a diff cover instead of removing a drain plug.
If the differential oil can only be changed by pulling a drain plug, I like to drain the factory fill early, run a cheap gear oil for a short interval, then use premium gear oil.
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