Just got my front end apart and realized the axle housing was full of moly grease instead of 90 weight. I don't know if this is because the axles have never been serviced and it has just been seeping into the differential for 16 years or if the PO put that in for some reason. I can tell it is moly grease mixed with 90 weight b/c it is thinner than pure moly.
Moly Grease in Front Differential (1 Viewer)
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Yeah I'm in the middle of doing the birfs. One was shot but the other has already been replaced. I'm just wondering how to get all that moly grease out of the axle housing. We were going to try spraying solvent inside the housing and diff to try and clean it out. Any other ideas?
Heated pressure washer to get it all out
If you drop the knuckles and the diff... you could hook a rope to a rag and thread it through with some diesel.
Cruiserdrew
On the way there
Do the fix, then cycle through 3-4 weekly changes of 80w-90. Use the cheap stuff, and it will clean it all out.
And a cup of ATF wouldn't hurt for the first change out, it will capture any moisture that might be in there and help clean things up.
I'm not a big fan of solvents unless you can remove them before you put it back together.
You can also jack it up higher on each side to get the soup to drain to the middle.
If you have the birfs and inners out, might as well pull the front diff and give it a check up.
There was a ton of grease mixed in the gear oil when I did the first drain and fill, but not much if any of gear oil in the knuckles. The diff fluid was black and the consistency of chocolate syrup. But no birf soup in the knuckles.
So, bottom line is that now I will be re-gearing the front a lot sooner than I had planned.
X2 on the weekly changes to clear it up.
There was a ton of grease mixed in the gear oil when I did the first drain and fill, but not much if any of gear oil in the knuckles. The diff fluid was black and the consistency of chocolate syrup. But no birf soup in the knuckles.
So, bottom line is that now I will be re-gearing the front a lot sooner than I had planned.
X2 on the weekly changes to clear it up.
ToyotaDon
I am here
I saw a post once where someone said something about the diff breathers contributing to this. I think it had to do with them getting plugged and causing a vacuum inside the housing. Does anyone have more info, what needs to be done if they are plugged up?
ppc
M Go Blue
There are two issues. When you go into a deep water crossing the axle housing cools very quickly causing a vacuum even if the breather is partially working. It isn’t very high so water could get sucked into the housing via the breather. The vacuum will draw grease in from the knuckles and water may get sucked into the knuckle. If the breather is blocked during normal driving, the diff will build up pressure from the heat, forcing diff fluid into the knuckles. When things cool the mixture of grease and diff fluid get sucked back into the housing.
Pull the breather hose off the truck taking the hose off the axle and remove the standoff that holds the other end upward. Buy a new length of hose long enough so it can reach the back edge of the hood/firewall. Now you could by a cheap plastic fuel filter or I've found some cone shaped stone type filters at an industrial hardware store or you can reuse the original cap but it needs to be modified. The reason it plugs up is that underneath the metal cap is a rubber flap and a spring. When this gets the dirty mucky diff fluid in it the flap will stick shut. Pry off the cap after trying to bend straight the crimps. Remove the flap and spring. Put the cap back on and recrimp. When you reinstall, run the new hose back as high as you can get it on the firewall. This is the highest spot outside the truck and will allow you to make high water crossings without the breather taking in water. The transmission, transfer and rear diff need a similar setup. Make sure there is a nice smooth path from the diff to the firewall. No sharp bends, loops or low spots. Zip tie it in a few spots loosely and its good as gold.
Agreed on all counts, and I wouldn't sweat getting every last bit of moly out. On my truck there is always a little migration of moly grease from the knuckles to the axle--regardless of new factory seals, Marlin seals, or different birfs.
Sounds like your current situation is pretty extreme, but a little moly in there won't hurt anything in my experience--I regeared last year an my diffs looked excellent after 185,000 miles, despite going through periods of moly soup.
If you're going to remove the diff, might as well pull a rag through there to get any thick stuff, but otherwise I'd just cycle some gear oil changes to get the bulk of it. No worries.
Sounds like your current situation is pretty extreme, but a little moly in there won't hurt anything in my experience--I regeared last year an my diffs looked excellent after 185,000 miles, despite going through periods of moly soup.
If you're going to remove the diff, might as well pull a rag through there to get any thick stuff, but otherwise I'd just cycle some gear oil changes to get the bulk of it. No worries.
I agree with the seals letting in the grease. I also would just fill and empty the diff. several times over the next month to get the extra grease out;Do this when the cruiser has just been run and the oil-grease mix is still hot.I use a small childs swimming pool underneath to catch the mess. Even with extra grease IM not sure it hurts anything. mIke
This is what I logged on to investigate. I went through a lot of mud/water recently and just wanted to check. My transfer and rear are always clean and golden. The front always has a little grey hue to it but the consistency is the same as the oil.
I never get any diff oil seeping the other way. But I was having anxiety about the grease in the diff fluid.
Just found out that my rig has Birf Soup...in the Diff. Have been checking the knuckles every few months, and they don't show any migration of 90W, but when checking the level of the diffs today, found that the front was a gooey grey mess.
The kicker is that a local shop setup my ARB's last year, and likely botched the OEM seal install (which I gave them to install). Will figure that one out once the front end is pulled apart. Not sure if I will do the job, as I will be travelling until the end of the month, and want to be sure to get to Surf N Turf this year...may see if I can get in on the Robbie NorCal visit for a day.
Drained out the goop, and refilled with new diff fluid. Will keep doing that until I can get 'er fixed.
Steve
The kicker is that a local shop setup my ARB's last year, and likely botched the OEM seal install (which I gave them to install). Will figure that one out once the front end is pulled apart. Not sure if I will do the job, as I will be travelling until the end of the month, and want to be sure to get to Surf N Turf this year...may see if I can get in on the Robbie NorCal visit for a day.
Drained out the goop, and refilled with new diff fluid. Will keep doing that until I can get 'er fixed.
Steve
I had issues with my front diff getting moly sucked into it and plugging up my breather line and extended my diff breathers front/transfer/tranny/rear and haven't had a problem since. Ran a dedicated one for the front diff up the firewall near the brake booster and put a small fuel filter at the top and haven't had a problem since.
I had the same problem with soup. My axle seal was fine with the spring still there, and the diff breather was clean and free flowing. I figure it was the original drive flange, which I hadn't replaced when I recently did my front end rebuild. I only had soup on the PS, with the old worn drive flange. The drivers side birf is fine however, and I did replace that drive flange when I did the front end rebuild.
https://forum.ih8mud.com/80-series-tech/419751-worn-drive-flange-birf-soup.html
https://forum.ih8mud.com/80-series-tech/419751-worn-drive-flange-birf-soup.html
Tossing around ideas as to why soup would only be in the middle of the diff, and not in the birfs.
My first theory is that the grease gun fitting being too tight of a fit in the fill-port. A few pumps, and the pressure adds new grease, but also pushes any grease next to the (worn) seals into the diff. Perhaps seals are not too shot to keep the diff fluid out, just giving-way to the internal pressure in the birf, which is not a normal operating issue.
I am going to start filling my birfs without the grease gun end piece, so that this is not a possibility. I will be changing the diff fluid once every 500 to 1000 miles until I get things sorted (ie front end rebuild). Will see how much intrusion happens in the near future.
Steve
My first theory is that the grease gun fitting being too tight of a fit in the fill-port. A few pumps, and the pressure adds new grease, but also pushes any grease next to the (worn) seals into the diff. Perhaps seals are not too shot to keep the diff fluid out, just giving-way to the internal pressure in the birf, which is not a normal operating issue.
I am going to start filling my birfs without the grease gun end piece, so that this is not a possibility. I will be changing the diff fluid once every 500 to 1000 miles until I get things sorted (ie front end rebuild). Will see how much intrusion happens in the near future.
Steve
