Front diff fluid very low on drain & fill.

[silver02accord]

I last changed my front diff fluid 5 years ago and 30k miles with some decent wheeling in there. I drained today and only about 200ml(edited to 400ml of fluid that drained out) of fluid came out. No leaks at cv. The drain plug didn't have any big chunks on the magnet. Fluid was black/dark but didn't smell terrible-rear smelt more sulphry. I don't understand where the fluid could have gone. I took my truck to a mechanic about a month ago to get a new power steering rack installed but they did not make a note of changing any differential fluid. Should I just look to do a fill and then re-drain it in another couple hundred miles and put a new fluid? No adverse sounds or performance that I am hearing.

 

[TahoeZ]

How does the pinion seal look?

I would add new fluid and do another drain/fill around 1k miles to inspect.

 

[silver02accord]

How does the pinion seal look?

I would add new fluid and do another drain/fill around 1k miles to inspect.

dry as best i can tell- i have skids on full time so i'd think id see some fluid accumulation there.

 

[OEMGUY0720]

Should I just look to do a fill and then re-drain it in another couple hundred miles and put a new fluid?

This is what I would do for the sole reason of reducing contamination from old fluid.

Did you also serviced the t-Case and front differential fluid?

 

[silver02accord]

This is what I would do for the sole reason of reducing contamination from old fluid.

Did you also serviced the t-Case and front differential fluid?

Yes I changed t case and rear diff a few days ago. Today I changed front diff and noticed the super low fluid. I grabbed some fluid from the front diff and may send it to Blackstone to see what they say. But if everything is driving fine(and has been for last 30k) I am hoping there isn't much to worry about.

 

[OEMGUY0720]

Yes I changed t case and rear diff a few days ago. Today I changed front diff and noticed the super low fluid. I grabbed some fluid from the front diff and may send it to Blackstone to see what they say. But if everything is driving fine(and has been for last 30k) I am hoping there isn't much to worry about.

Nice. I think your rear differential is fine, as long as there are no obvious large shards of metal on your next drain and fill you should be fine and no noticeable/loud grinding noise. Try to get the LS-rated diff oil -it has friction modifiers additive which addresses heat.

 

[baltistyle]

As always, check your breather to make sure it’s clean and free…

 

[Trapper50cal]

Mine leaks from the passenger diff side/carrier bearing and seal (where the CV enters the diff housing)

 

[silver02accord]

I wanted to circle back. Still didn't discover any leaks but changed the fluid after 3-4 heat cycles and about 40ish miles. Just some small mush like the first time so hoping I avoided a bigger issue. Fluid draining out looked new(it should only 3 days old)! Using mobil 1 synthetic 75-90 LS. Video attached showing the debris on the magent.

 

[OEMGUY0720]

^^This is good news despite of the tiny collected material, from experience you are still within spec, as long as there is no leak and excessive backlash/clunk on the third member (pinion and ring gear) your 100 is good to go for regular use. Of course if you will rock crawl this, that’s a totally different amount stress the drivetrain will endure so I would say operate the equipment accordingly.

 

[Jay Tea]

Interesting, seeing as there are no leaks from the pinion or output seals, I'm inclined to believe it was either under-filled (unlikely as you seem competent) or someone had drained out most of the fluid when replacing the steering rack.

I've not replaced my rack before but its possible they drained out some of the diff fluid prior to pulling out the CVs and forgot to top it back up.

 

[silver02accord]

Interesting, seeing as there are no leaks from the pinion or output seals, I'm inclined to believe it was either under-filled (unlikely as you seem competent) or someone had drained out most of the fluid when replacing the steering rack.

I've not replaced my rack before but its possible they drained out some of the diff fluid prior to pulling out the CVs and forgot to top it back up.

I've not done a rack either - do you know if it's standard practice to drain diff fluid for a steering rack job? Because this same shop let me leave with a coolant leak right at the oil filter so I am already on high alert with them.

 

[Jay Tea]

I've not done a rack either - do you know if it's standard practice to drain diff fluid for a steering rack job? Because this same shop let me leave with a coolant leak right at the oil filter so I am already on high alert with them.

I don't see why you would need to touch the diff when replacing the rack but that's the only explanation I can think of as to why the diff fluid is low.

You do need to remove the oil filter assembly though and if they didn't replace the o-rings then that would explain your coolant leak.

 

[TahoeZ]

I would run it.

If no leaks, it was underfilled. If not by you, then by the shop. Those are the only two potential causes.

 

[silver02accord]

I would run it.

If no leaks, it was underfilled. If not by you, then by the shop. Those are the only two potential causes.

That's what I'm thinking - thinking it was likely me at this point!

 

[TahoeZ]

I have seen people spill some oil onto the filler threads, then it starts dripping out and they think it’s full. I like to re-top off a couple of times to make sure and always keep track closely of how much I put in.

 

[silver02accord]

I have seen people spill some oil onto the filler threads, then it starts dripping out and they think it’s full. I like to re-top off a couple of times to make sure and always keep track closely of how much I put in.

Ya this time I didn't mess around - filled it till it dripped. Waited 5 min filled to drip and repeated once more. Also made sure to get 1.8 qts of the bottles used up.