I seem to have oil coming out of a seal on my front diff. It's at the front where to tailshaft goes in. I'm guessing that would be called the input? The diff is a rockwell. The oil is coming out here. This is my first truck so I'm looking for advice on fixing it, things to watch out for and maybe even some shortcuts. The filler plug for this section seems to be right on top. After I replace the seal what level should the oil be filled to when the plug is right on top. I'm worried that too much oil might blow the seal again. I've been topping it up thats why it looks so dirty. is this the diff lock? the seems to be a bit of black gunk hanging around here too. I've cleaned it since the photo so I'll keep and eye on it. I also have another question about my gearbox. I want to change the oil but I noticed today there are two filler plugs and two drain plugs. Do I just drain them both and then fill them both? The photo shows the two fillers. Thanks!!!
I'm going to take your questions in reverse order: 1. When changing trans. oil, definitely pull all the drain plugs. This insures that no dirty oil is trapped in low spots. Then pull both fill plugs, but, I think you will find they are connected internally. Just fill it up to the level of the highest of those two. Make sure you clean the vent, which you should do every time you grease the truck. 2. Yes, that is the interaxle differential lock (power divider lock). I wouldn't worry about that little bit of dirt, unless it gets wet with oil. 3. The fill plug for the input section is just so that it can be filled with oil when you change the oil, or do other repairs, so that those bearings won't run dry. In normal service oil is pumped up to that section from the main axle housing by a series of oil slingers and grooves in shafts etc. Too much oil can't blow a seal as long as the axle vent is open. If you haven't changed the oil in this axle, I would drop all the drain plugs and change it when doing this job, otherwise, just drain the input section so you don't wear the oil. Like any other time you are under the truck, clean both axle breathers, and the trans. breathers. If these get clogged, the vapor expansion from heat will push oil out through some seal. Also, make sure the breathers are in good shape, since they can suck dirt in if they aren't. 4. Ok, now to the main question: First, before you drain the oil, lay down and grab the driveshaft just in front of the yoke and shake it up and down. If you feel movement, check to see if it is in the u-joint or the axle yoke. If it is in the yoke, drop the u-joint and try to tighten the nut in the center of the yoke. If the nut is loose, tighten it real tight and see if the free play goes away. If it does, clean the area well, put the driveshaft back in and drive the truck to see if you have fixed it. This is a long shot but I have seen many trucks come in leaking because the yoke is loose. If you tighten the nut and the free play doesn't go away, you have bad bearings, and will be another whole story. Once the free play is gone and the seal is still leaking, just drain the oil from the input section, drop the u-joint, (don't forget to watch for about a million needle bearings),and loosen the nut in the center of the yoke. Most times the yoke can be gently driven off the splines, but sometimes they can be an absolute bear. Be careful if it fights you not to hit it too hard and warp it, though this is hard to do. Sometimes it helps to wrap a sling around it and hook a come-a-long somewhere on the truck frame. Pull as hard as you can on the come-a-long, then hit it with your 3 pound hammer. Occasionally, you have to build or buy a yoke puller, and still beat it with a hammer. Once you get the yoke off, look at the surface the seal rides. If it is just a little worn you can usually just clean it with sandpaper to get any sharp roughness off and reuse it. If it is deeply grooved, you will have to replace it or use a speedi-sleeve. Now, just pop the old seal out, put a thin film of silicone gasket maker around the outside of the new seal and tap it in gently but firmly. Put some gear oil on and behind the inside of the seal, and on the yoke. Push or tap the yoke into place, then tighten the nut very tight. Reconnect the driveshaft, put oil in the input section, and drive the truck. come back and shake the driveshaft again. Do this every so often for the next few weeks, as sometimes the yoke won't seat at first and the nut will need re-tightening before you destroy the new seal. Well, now that I have written you another book, I am going to finish my lunch, Mitch
Mitch you are a living legend. Thank you once again for having all the answers. Is this vent you speak of the same as a breather like on the diffs? Or is this something different. If so what does it look like? It did have a bit of black scum hanging around, here is a close up view of it. I've cleaned it now but I guess I'll have a look again and see where the oil is coming from. Standby for more questions The breathers seem ok to me, but I'm no expert, they move when I wiggle them and they show signs of oil that has come out. Is that how they should be? The shaft seems pretty solid. I can't feel any movement. I did notice that the bit between the yoke and the diff (a dust cover perhaps) did flex a little when I pull on the driveshaft. I will try and tighten first and see if it helps. Ok the part about a million bearings kind of scares me. I never dropped a u-joint before, (total noob). Do I pick these bearings up off the gravel and try to use them again? How heavy is the shaft? Can I just drop it to the ground? I think I will lay clean cardboard on the floor. Do I just undo the 8 bolts and see what happens?? Noob again, can you explain "surface seal rides"? Thanks again Mitch!
Okay, easy questions first: I wouldn't worry about that greasy spot unless you start seeing oil running down, otherwise fixing it will be more trouble than it's worth. The trans. breather should be the same as the axle breathers, and if they wiggle and you wipe off the accumulated dirt every so often they should be fine. If in doubt, you can unscrew them and blow through them, or wash them. Sometimes you see that somebody has removed one and put in a pipe plug, but they are important. The axles only breathe from cooling and heating, but if you get a tiny internal air leak in the transmission that otherwise wouldn't hurt anything, it can build pressure fast. To explain "the surface the seal rides": The tail of the yoke slides through the seal and into the housing. When you pull it out, you will be able to see where the seal has been rubbing, or "riding" it. Look and see how bad the seal has worn the yoke. Depending on length the driveshaft is not extremely heavy, but can be awkward. I tie a rope or strap from the frame rails under the shaft loose enough to let the shaft drop about 50mm. This keeps it from falling on my head and lets me lower it when I want to. Ok, now for the u-joint, or as they are known in America, the pain-in-the-ass: My brother is the only truck mechanic I know who likes u-joints, but he's never been quite right. Most of the time you can drive them out w/ a 3 or 4 pound (8kg?? ) hammer, but sometimes they can be bad. I have had to resort to torching out a few. Leave the bolts in the caps on the driveshaft and loosen , but don't quite remove the ones in the rear end yoke. Hit the driveshaft yoke w/ the hammer and drive the caps out as far as the bolts let you. Take the bolts out and drive the caps the rest of the way out, keeping the cross of the u-joint in both caps as long as you can, then keep it in the one you are driving out. As long as you keep the cross partway inside the cap, the bearings can't get out of place. If you do drop the cap, the bearings will come out. If the cross comes out of a cap and you stick it back in, the bearings can fall down inside the cap and get broken. If the bearings come out you can put them back in. They stand up against the wall of the cap, and a little grease will glue them in for you. If you lose one bearing, buy a new u-joint. If something is going to get messed up: The u-joint (cross, caps, and bearings) comes as a kit for about $35 and is easy to get. The rear end yoke is about $200 and will be harder to find. The driveshaft and it's welded on yoke will cost more, and have to be made. Now, another subject: If I am going to spend my lunchtime between bites training you, you should buy my lunch. So, I'm just going to tell the waitress I'm leaving and an aussie guy will mail her $7 US soon. Good luck, and let me know how you come out, Mitch
Mitch I'll buy you breakfast lunch and dinner if you keep helping me, where do I send it? And $7, thats a Bargain! So I got the u-joint out and it wasn't too bad. A bit of a puzzle trying to actually detach it from the yoke after removing the caps. No bearings fell out, they were all nicely glued in with grease. I managed to tighten the yoke nut about a 6th of a turn. Put it back together and drove for 10 minutes, not leaking so far... so I'll keep and eye on it. Thanks again for all your help. I drained the gearbox oil and there was not much in there, I'd say about 2litres (1/2 a gallon). Damn that scared me! It filled up now and the vent on it brand new and looks like no oil has ever passed through it. I took it off and blew through it and it is all clear. Now while I was out there working on it I thought I take a look at this problem and put a new gasket in. Oil seems to be building up on a few of these nuts.... I undid all the nuts but couldn't get the cover off so I took the wheel off to try and get a hammer in there when I saw this.... Then I took the second wheel off and discovered a whole lot of black muck, I don't know if its grease or oil but some of it looks fairly solid... I can't imagine those brakes are very effective with all that muck. So what have I got going on here? and you guessed it, how do I fix it? Many thanks and many lunches!
Looks like your axle seal is leaking. I recall someone giving the description on how to replace it recently, maybe some else's memory is better than mine and can link to it.
Thanks Steve, So I guess that means the bearing will be running low on grease right? Does that explain why its leaking on both sides? Is there a way to get more grease in there as a temporary fix so I can do a job on Monday? I promise I'll fix it properly after that.
Your wheel bearings run in oil from the rear end. By filling your axle housing up, you are refilling the wheel hub. Now as to running it on Monday, the real question is: is it just a bad seal, or bad bearings? If it's the seal, as long as you keep it full of oil, and aren't talking about many miles, it'll PROBABLY be ok. You're right that those brakes aren't doing much. If the bearings are loose, you can ruin the hub and axle housing, kill somebody if the hub and tires come off, or set your truck on fire. I have personally seen each of those results more than once. If while you have that wheel jacked up, you back the brake shoes way away from the drum, and then pry up and down on the hub or tires and see no movement, you MAY be ok. If you don't back the brakes way up, the shoes against the drum will hold it from moving. If you see no movement and are going to try it, check and fill your rear end oil today, then check it again Monday morning. This will give the oil time to run through the bearings and into the hub. Personally, I'd change the seal, but, I keep wheel seals in stock for my trucks and can change it in a half hour in a gravel parking lot. I think I covered how to do it in that thread where we were talking about your brakes. BTW, that cover you were talking about is the end of the axle, it runs all the way to the center of the truck. To get it loose, back all 12 nuts up til they are flush w/ the ends of the studs to protect the threads from misses, and knock the heck out of it w/ a 10 pound hammer until it bounces free. Once it moves, look and see if you have cone washers or regular lock washers behind the nuts. If they are cone washers, you will want to pull them out individually before you pull the axle out. Tighten these nuts good when you put it back together, and check them periodically to make sure they are still tight. Good Luck, Mitch
Ok I've decided not to take the risk. I've had a wheel fall off before and I don't want a repeat performance. Also I can't get a part number until I pull the seal out and because is Saturday all the the shops shut at midday. Looks like I have to get the seal on Monday. How do I tell if the bearings need replacing when I pull them out? or should I try your method above before pulling them out? Here's the link to the other thread, its the second post where you explain how to do it.
Just look your bearing rollers and the races they run in over carefully when you pull them out, make sure there are no chunks or streaks gouged out, and they are smooth. The rollers are supposed to be loose in their cages. When you put them back in, tighten the inner nut, then spin the hub, and tighten the nut again until it is fairly tight, back the nut off a few turns, tighten it again while turning the hub, then back the nut off 1/6 to 1/8 turn as necessary to line up the lock. It is better to be just a tiny bit too loose than too tight. Then tighten the outer nut tight and do whatever is needed to the lock. Don't forget to put the inner bearing back in before installing the seal, and don't forget to put some gear oil in the hub after putting it on the spindle and before putting in the outer bearing. Good Luck, Mitch
One good thing to do after reassembling the wheel is to jack up the opposite side about six inches, so the oil in the center of the rear end will run out to the end and fill the hub.
Ok I have to confess, I chickened out of trying to fix it. The weight of it was worrying me because I already hurt my back lifting a piano last week. The good news is it's all fixed now, i don't know how much it will cost, he hasn't sent me the bill yet. Thanks for all your help guys especially Mitch. The bearings had big chunks out of them so I'm really glad I didnt just top it up and keep driving!! Back to the original post, there is still no oil leaking from the front diff input. I noticed that the nut has loosened off about 1/12th of a turn. I guess if it keeps on getting loose it will keep on leaking. any suggestions to stop it getting loose?
The best way is a new nut. If you don't have a new nut, clean the threads well and apply some blue Loctite.