Sounds like a bad movie title, but there was a bunch of foamy goop on floating on top of the gear oil in my rear drive axle. Glad I'm on this maintenance item! Gotta assume its water :-(

Edited January 22, 201411 yr by joecool911

Looks like foam to me, doesn't appear to be water, if it was water it would be milky. I would be more concerned about what that chunky dark sludge is running out just below the ring gear in the picture.

Edited January 22, 201411 yr by Wild and Free

Does the oil foam like that on its own under normal operation?

Awful burnt looking too being the oil is for sure dark in color. Broke down from heat?

Different brands of oils and different additive packages will make the oil foam and look like that in some cases. It is hard to know as the flash can change the color of things and make it look better or worse as well. I have seen some brand new gear lubes look like that right from the container over the years.

Edited January 22, 201411 yr by Wild and Free

its normal for it to foam up some when its been running, I'm guessing you had been driving your truck soon before you pulled the diff cover off?

 I have not seen any in either of mine when changing. But mine usually sits overnight before changing. I dont think have ever just parked and pulled the cover.

It's been so cold that I did purposely drive it to aid draining of the old. Could just be foam. Very dark. Had grey silicone sealer. Don't know if that's factory original or if it's been previously changed prior to my ownership. That's why I'm doing everything. I'll soon know where I am in regards to maintenance. I only got the rear done today. My hip doesn't respond well to crawling around on gravel under the truck.

Used a syringe to pull the gear oil from the bottom of the pumpkin to allow for continued drainage without spilling over onto the sealing surface. Worked well. Tightened bolts to 15 pounds. Not sure what's proper?

Oil was dark. After a couple hours there is still foam setting on top of the oil pan. I'll take a picture and post.

Here ya go, 3 hours after draining. Doesn't appear to be water contamination at further inspection.

Fluid level also was low. My pinky could not reach any gear oil in the fill hole. I noticed when filling the unit that still a little bubbly was present on the top of the new oil. Reminds me of stout home brew. Yummy! Should crank up a batch here soon. Very expensive as home brew goes. Lots of roasted grain. Almost like French roast coffee beans.

Edited January 23, 201411 yr by joecool911

It's a fair amount if work to break the seal on the pumpkin and get it re-sealed. If you've got no leaks, is there an advantage to fluid change that way or should we simply extract fluid with a pump and refill? Could probably do that in 1/4 of the time.

I like to pop the cover for inspection purposes if nothing else. I jack the axle up I'm servicing and rotate the ring and pinion slowly and look for any signs of heat discoloration, cracks or chips in the gear set.

A sharp scraper and a hammer works great for seperating the cover. Just tap the scraper in between the axle and cover until the seal breaks and work your way around.

Still awfully foamy still. I've never seen mine hold foam for very long after. I typically pop the cover with a putty knife. As for checking fluid level I should be able to loosen the plug tip it slightly grab a sample of fluid running out screw it back in and be done. I never have to dip a finder or screwdriver to check levels. How I fill is I fill to it running over then using my thumb as a dam fill just a bit more and through the plug in. Axles, transfer case and transmission.

I looked on Internet for foamy discussion. Sounds pretty common. The gl4 and 5 have anti foam additives as I understand. I'm going to run her a while and see if it improves. The fluid was unquestionably burnt. Maybe original 179,000 mile fluid? Pan of old fluid looks the same this morning as it did in picture from yesterday and I see no sign of water. I'll remove the fill screw in a few days and inspect level and look for any signs of foam. Seems to ride on top of fluid. Maybe if I over-fill and let it run out it'll remove any foam remaining on too of new fluid.

Edited January 23, 201411 yr by joecool911

if this truck  was  purchased used,   hard to tell  how many different  oils  have been  'added'  over the years...  and if they are even   compatible with  was in there in the first place!     (I suspect someone  put   a little  auto trans fluid  in yours!)

 

You did the right thing and   dropped it all,   and  started over with  fresh (and  correct type)

 

 

I'll even park the  truck so the pumpkin will drain out easier,  uphill for  rear,  downhill for front.   Take a hand  sprayer full of  diesel fuel,  and   douse  the  whole works  out.   (works better in  warmer  climes,  gear oil  don't want to  'cut'  when its 0 degrees..)    mop out the bottom of the  pumpkin...  and   close her up.

 

no doubt  sucking it out  the  fill hole is faster,  but   you'd never see any  'badness'   (filings, chunks  etc)  unless you  take the cover off,  and   expose the whole thing

Edited January 23, 201411 yr by rancherman

Front axle went without a hitch. Dark, but not as dark as the rear and no foam. Both axles low on fluid. Now that I know where I'm at, I'll keep an eye on the level of oil in the axles. I have not seen any leaks, so I don't know why they were both low? I'll fill them as Michael suggests. Thumb over the hole and slightly overfill the plug hole.

Thanks guys!!!

Not a good thing to overfill. overfilling can result in overheating and I have seen it puke out the breather and cause a vacuum and pull even more out the breather once it starts and you could have the seals submerged that are meant to keep splash lube in too. If you fill it to the proper level which is supposed to be just under the fill plug once it is warm it will be above the fill plug a bit anyhow.

Edited January 26, 201411 yr by Wild and Free

well,  If  you   can't see any  signs of   leakage,    I  can  guess    why  it  was low!      urban  legend    has  it     that  running  a little low  can save  fuel.  I  said  in above post that   there may have been  a little   ATF    added   at some point.... again to    help out with     economy...    They may  have  some  merit,    but   I  don't like to take  chances  intentionally! 

 

Glad  you got it  drained out  and   filled  up  with the  good  stuff!       

I leave my oil level in my axle's about 3/4 inch below the fill plug, they always seem to leak a little when filled to the brim but not when its about 3/4 inch low.

LOL,  to tell ya the  truth.....   when  I  DON'T see a little  seepage,  that's when  I get worried!!!         Most of  my      crap  is  old enough to vote... and  possibly    draw  pension...    And     when  I  see  something  suddenly  'dry up'....   time to  get the  jug(s) out!

I Always slightly over fill mine. No leakage at all.