I changed the diff fluids the other day. When I drained the front diff, some very thick grease-like stuff came out of it instead of the consistency you would associate with normal diff oil. Any thoughts on what happened to the fluid? Could there be a leak from the birf grease getting into the diff? There was a lot of this stuff that came out. Thanks.
Thick goo came out of front diff (1 Viewer)
- Thread starter toyman317
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That is strange. I would have expected the flow to be towards and out upon your wheels rather than towards your pumpkin, considering that grease is pretty thick, if your oil seal had failed. Is it possible some fool pumped grease into your diff ?
Kalawang
Kalawang
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- #4
I suppose that is possible. The birf area doesn't look especially leaky. I will try to post some pics of that area. This truck only has 128K and I have only had it for a month. Don't know the PM history. I was planning to do a rebuild anyway just as PM but it sounds like I need to do this sooner rather than later.
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- #6
Well Doc so far I feel lucky after your comment. I drove this truck back to Indy from Philly and have been driving as a DD for a month. I don't hear any noise at all coming from the front axel so hopefully the damage is nil at this point. I will heed your advice though.
I'd worry more about your birfs, which may be 'dry'. That's why I wouldn't drive it until re-built.
If you had no other option but to drive it, you could pull the front drive shaft, drive flanges, and re-fill the diff. Once the flanges and shaft are pulled the front axle should remain motionless while driving. You'd still get some movement from steering, however. Since you have 'spare' vehicles- I'd go that route.
My 80 sat up on jackstands for nearly a month after I first bought it, as I was learning how to do the front axle and other jobs.
If you've never done a front axle- I may be in your neck of the woods fairly soon and could help you through it.
If you had no other option but to drive it, you could pull the front drive shaft, drive flanges, and re-fill the diff. Once the flanges and shaft are pulled the front axle should remain motionless while driving. You'd still get some movement from steering, however. Since you have 'spare' vehicles- I'd go that route.
My 80 sat up on jackstands for nearly a month after I first bought it, as I was learning how to do the front axle and other jobs.
If you've never done a front axle- I may be in your neck of the woods fairly soon and could help you through it.
my understanding is that the diff breathers can malfunction and cause a vacuum in the diff - ie, the diff heats up when driving and the extra air is pushed out of the breather, then you hit a puddle or something else cools the diff off but the breather doesn't allow air back in creating a vacuum that sucks the grease into the diff.
I would pump some grease into the knuckle and keep an eye on the diff fluid until you can do the front axle job asap. there is almost certainly gear oil in the knuckle also.
I would pump some grease into the knuckle and keep an eye on the diff fluid until you can do the front axle job asap. there is almost certainly gear oil in the knuckle also.
bpenn1980
SILVER Star
Yes, I thought the consensus was that the diff breather creates a vacuum and sucks some grease into the axle housing and third? You guys know better than me, but I did extend both diff breathers to the engine bay and capped with a cheap fuel filter because I had heard that.
I just drained the front diff on my 40 and I got the same thing. Thing is I just rebuilt the front axle about a year ago (maybe 5000 miles). I took off the plug on the knuckles and did a visual and also stuck a zip-tie down into it as far as I could and all that came out was good moly grease, no signs of oil. I believe that I just sucked the grease into the diff and not the other way so I'm fillling the diff back up and adding some grease to the knuckles and will just keep an eye on it. Just adding a data point that this is possible.
I'm new to the 80 world (just got one in Dec) but don't 80 knuckles have plugs on top to add/check grease like the 40's do? Couldn't you add some just to keep you going if needed until time to do the axle rebuild? Maybe not the best practice but better than doing nothing.
Does the grease cause any harm to the diff?
Eric
I'm new to the 80 world (just got one in Dec) but don't 80 knuckles have plugs on top to add/check grease like the 40's do? Couldn't you add some just to keep you going if needed until time to do the axle rebuild? Maybe not the best practice but better than doing nothing.
Does the grease cause any harm to the diff?
Eric
bpenn1980
SILVER Star
I think the problem is that adding grease to the fill port doesnt easily allow it to get back inside the bell housing which is where the action happens.
[EDIT: This is not the case, I stand corrected]
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I remember reading a post where someone had a clicking birf and was able to get it to stop by just adding grease and driving, hence showing that the grease will eventually work its way in there. Again, not the answer to the problem.
We just rebuilt the front end on my 80 this past saturday, I bought the truck in Dec. and the birf was clicking then. I checked the grease level in the knuckles and they were both very dry, only a little bit of birf soup in there. I knew we were going to rebuild the front end in a couple of weeks, but i went ahead and greased the knuckles anyway just to prevent any further damage. The driver side knuckle took almost a tube and a half of grease before it was brought up to the proper 2/3's full level. Almost all of the clicking immediately went away, i'd say about 90%. The birfs looked real good once we removed them for the rebuild, and after all new seals, bearings, and fresh grease throughout there is no clicking at all.
Yes, the front diff vent flapper valve gets clogged with crud over time and it also holds a vacuum in the diff as it cools after driving. This draws grease from the birfs into the diff gear oil. Solution is to extend the vents with a couple feet of fuel line - takes 15 minutes and about 15 bucks.
As for grease put into the square plug, yes it ends up in the inner bell housing with the birf joint in short order. This was a surprise as we'd all long assumed it would not. I did it using two different color greases before I repacked. Fully blended in only a few days time.
DougM
As for grease put into the square plug, yes it ends up in the inner bell housing with the birf joint in short order. This was a surprise as we'd all long assumed it would not. I did it using two different color greases before I repacked. Fully blended in only a few days time.
DougM
I changed my front diff the other day and it looked exactly like you explained it.. I thought that it could be water mixed in somehow.. The rear diff was not as soupy or thick.
It's bad to the extent that a lube designed for one application is contaminated with lube designed for another. Obviously you are the one that has to assess the degree of contamination, the time since last service, your ability to correct it or pay another to, your future ownership expectation, etc. It's not a show stopper in and of itself, but a blown birf's gotta require near a grand worth of parts to correct vs $150 worth of gaskets and grease to avoid. Post a pick and the previous maintenance interval and you'll get some excellent feedback.
DougM
DougM
- Thread starter
- #17
Here are pics
Here are some pics. The first one is the passenger side and the second is the driver side. No expert here but I would guess the driver side seal is the one leaking. Right?
Here are some pics. The first one is the passenger side and the second is the driver side. No expert here but I would guess the driver side seal is the one leaking. Right?
whoa - they are both gone. drivers side is long gone.
- Thread starter
- #19
So does the second picture look like diff oil?
supercarrera
Club Esprit de Four
Man those are some nasty pics! Sorry, don't have much to offer other than you need a rebuild soon... 
