If the Birfs weren't done at around 60K, I'd say it's time for a repack. If you don't have documentation that they were done, then assume they were not to be on the safe side. It'll give you the opportunity to clean up the knuckle and replace the seals/scrapers anyway.
When I did my front axle (I too have/had a '97 with 92K) last month, it didn't look like there had been that much seepage (as indicated in the picture); it was much "dryer". I didn't have any diff fluid in my knucle either that I could detect. But that picture looks like sumpin been seepin compared to mine. I'd fix pronto...though you guys seem to think it about norbal.
Yours looks like it's been leaking for an extended period of time - Mine looks kinda similarly "wet"; but only in the lower portion where some wet grease drops are starting to form (they were dried grease a few months earlier) - Took my car in today for inspection. It was the internal seals the culprit (gear oil mixed with axle grease).
Looks normal for the miles. Generally speaking, it's time for a repack/seals when you actually find drips on the floor, but what I see is normal seepage. In other words, no need to rush out and panic but directionally it's something you should get to eventually. If you hear clicking while accelerating at full lock, or you plan an extended trip, or you are a HD user (oversize tires/wheeling/towing/offroading), then don't wait for the drip.
um, Doug that "wait for the drip" advice is what my mechanic said when I bought it. He was wrong. one of my birfields went dry and grenaded 3 weeks after he looked at it,and the other one was nearly dry when they opened it. At the time the knuckle only looked wet in the lower portions (maybe because everything had leaked out years before!). I would say go by mileage. Mine went at 123k. Toyota recommends the service at 60k.
You hit it on the head - yours likely had dripped itself dry and I'm surprised your mechanic did not consider this possibility when advising you at that mileage. I think it's valid advice but obviously if you haven't owned it since new/low miles then you should consider the possibility Semlin raises might apply not only to the birfs, but to every fluid and service item. Upon buying a used car, it is not uncommon for me to spend $300 in fluids, tuneup parts, manuals and the like.
Waiting for a drip is probably a mistake. Semlin probably had a set of seals last an abnormal amount of time so diff oil never made it into the knuckles. If you look around at other vehicles you'll see that if a CV boot lasts the grease breaks down at around 125k. No different with our grease, and if that inner seal last longer than usual you won't get the lubricating benefits of it failing. A leaking knuckle is messy but not that urgent since it is being lubricated by the oil. What I see in the picture isn't diff oil but what is left of the moly grease breaking down and running out. I'd get it done immediately
I appreciate all of your comments thanks. Although this was not what I wanted to hear. I guess it will be good to learn how to do this since I will be driving this (by choice) for a very long time. Could be a lot worse. Right. Thanks again.
Here is my interpretation of what the pic shows and other things we know:
Background: The patient is a 97 with 95k miles. Prior axle service unknown; assumed never serviced. Also assumed is regular diff fluid changes and that prior services have *not* been pumping grease into the square plug at the top of the knuckle.
Diagnosis: Since this is a pic of the long side axle, it is likely that the axle tube seal will fail on this side first or this seal will be "more worn" than the short side. The seal on this side has a slight leak causing some mixing of gear oil with the moly grease in the knuckle. The liquified solution is still pretty thick but with 97k miles on the felt and rubber seals, some fluid is seeping past these knuckle seals. I think this is what we are seeing on the back of the knuckle.
Further Testing: An immediate drain of the front diff fluid is indicated. If the front diff fluid comes out in chunks then prior maintenance has probably been pumping copious amounts of grease at the back of the knuckle. This could get expensive. If the front diff fluid is full and drains with *no* trace of any grease then the problem is that there is probably *no* grease left in the knuckle and it must be repaired ASAP.
Recommended Treatment: If the front diff fluid is full and drains with a greenish color (indicating some grease contamination, but not heavy) then be sure to keep the diff fluid full, continue to monitor for more severe leaking at the back and bottom of the knuckle, and schedule the front axle service within a reasonable time/miles (depends on your driving as Doug mentioned.) Recommend no more than 6 mo/ 6k miles.
(Just having a little fun guys... don't get bent outta shape)
Ooh, good call. Draining the front diff is a good call to see what's happening up there. If you can't get the diff fill and drain plugs off (start with the FILL plug..) off, there was a thread on it a month ago or so.
First of all, what's a birf? I don't understand the suspension of these trucks very well, in fact all vehicles I've had have had front independent suspension, so I am unfamiliar with the straight axles on the front. Is there anywhere I can go for a technical explanation about the design and repair of these? How costly of a repair and how often should this be done?