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I was just randomly checking something under my truck and I noticed that I couldn't see a boot on either side of my 1999, 4x4 front axle. Is there supposed to be a boot there??? I mean, it seems that some dirt and grime could get up in there and trash the axle without one???
What I do have on both sides is a large o-ring looking thing . . . seems in decent shape. But it is a loose o-ring. On both sides it can be pushed back and forth about a centimeter, and just seems to sit on the axle behind the joint. My thoughts were that maybe, despite looking fine, that o-ring/gasket thing is not in good shape since it doesn't just sit tight up in there . . . I can't imagine I completely lost both boots if they had been there. If I do need to replace those o-rings, should I grease something up real heavy until I get the fix done?
There are no boots, but that o-ring thing is a dust seal that seals the axle and axle housing from dirt. There is an inner axle seal, so no worries about oil leakages. It sounds like yours are starting to give out...they always break. In mu opinion, I wouldn't bother replacing them unless you were to remove the axle to do front end work sometime (u-joints, ball joints, axle seal, diff removal) They are very common to break because of the amount of movement the axle has in the housing, hence, the dust seals need to flex alot, therefore breaking a lot.
FYI, if you ever do axle u-joints, get greaseable ones, then you'll never have to do them again (given they are maintained)
I'm with adamtheman16, it is a PAIN to tear down the front end just to replace those dust seals. It's not worth it. They are junk and will just separate and fall out anyway. The axle tube is just a big protective cover over the axle between the differential and knuckle anyway, so I wouldn't sweat it. I replaced mine at 182K when I did my ball joints and there was very little dust and sand in there and I off-road a lot.
Ok, thanks for the replies. Now of major concern is this: I just got back, yesterday, from my little 4wheel adventure. After 12 miles in 4wd, I stopped my truck, and it was leaking gear oil out from around those seals. It was on the left front side, closest side to the differential. What the heck does this mean? Needless to say I turned around and was able to get out most of the way in 2WD. I guess obviously a seal of some sort has gone bad in there, is it one of those dust seals? Is this a major job I'm looking at?
Yeah, the axle isn't the greatest for offroad use in water and mud because those dust seals rip and allow mid and water into the axle tube allowing the inner seals to leak. Unfortunately you have to pull the differential to replace the seals. The inner seals are hard to install, which makes it worse. The way the seal is designed, it can't just be driven with any ole hammer and punch or something. I had to buy the tool from ford to install it because I ruined the first one. After I got the tool, I realized how critical it was to have the tool.