I have a Ford 9” that has been slinging oil since the day I put it in…years ago. I think I’ll finally give up and attempt a fix. It’s evidently the front oil seal, which means attempting a rebuild which I have never done. What could possibly go wrong? So a couple quick questions - 1. Is this something I can do on the first try, or should I hand it over to someone with some experience? 2. I’ve been filling this thing up to the fill plug on the housing. I notice a blank off on the diff itself, where some have a fill plug down that low. Am I overfilling it? 3. Suggestions on lube oil? I’ve been using 75-90…I think…. Lol. I tossed the last empty bottle and forgot to note the weight.
It's common on the 9 inch to come up with a combination of carrier and housing with no fill plug since Ford moved it around. Two quarts is usually plenty and you can fill by pulling an axle. I have also done this before. Pick a spot on the rear of the housing away from the ring gear and in line with where the fill plug should be. Drill a 1/2" hole and use a self threading oil pan repair plug to create your own access.
You can do it in the vehicle, but I would pull the pinion retainer and do the job on the work bench. You can clamp the u-joint yoke in a vise to remove the retaining nut. It is going to take a lot of torque so the yoke needs to be securely clamped. The yoke should just slide off the pinion shaft. Be sure to support the retainer and pinion as they are the parts that slide off. Do a good inspection of the sealing surface on the yoke. Also carefully inspect the pinion bearings and races. You will need a new seal, a new crush sleeve, and I'd use a new pinion nut. When you re***emble note that it take a lot of torque on the pinion nut to begin to crush the crush sleeve. Once you get it to zero end play you can tighten and check bearing pre-load. You want to tighten the pinion nut until you get about 15 in-lb turning torque on the pinion with old bearings. Up to 20 in-lb would be okay. New bearings are to be set close to 30 in-lb. When you put the pinion retainer back in the housing you need to know if you have a non-hunting gear set. If you do, one of the pinion teeth will be marked with a dash or a splash of paint. That tooth need to engage another set of teeth on the ring gear. They will also be marked. If there are no marks on the pinion, it doesn't matter which teeth engage on the ring gear.
Mine has a fill port on the housing, but it’s way high up. So how much oil is enough? Should the axle tubes be full?.. half full?..
The blank on the carrier housing is the level for the oil that should be in there, wondering if that fill cap has a dip stick, if not you probably have too much in there which would cause the leak. You mentioned rebuilding, that may not be necessary, unless you’re aware of other issues not mentioned. Myself I would just replace the front seal, the yoke may be grooved by now and need replacement or sleeved
Isn't that port with the knurled cap a crown wheel inspection hole, and certainly not an oil level hole? Not surprised it leaked if filled to that level. Chris
What jaracer said is the correct way to do it, but there are cheaper ways to skin the cat and avoid other issues, my experience with rear ends is opening one can also open a whole can of worms as well, if it’s only the pinion seal leaking well your lucky. The job can be done without removing anything but the yoke and seal. Compressor and 3/4”rattle wrench, or a 3/4”breaker bar with a 36” or bigger pipe wrench and an 1 1/16” 6 point socket. Depending on how low the vehicle is your probably going to need to block it up, appropriate jack stands under the axels are best as applying torque to the pinion nut WILL move the vehicle if the tires are on the ground or blocking! Remove bolts holding prop shaft to rear yoke, wrap tape around u joint and move to the side, pulling it out of the trans will make a mess, application of e- brake will help hold, before anything else grab the yoke and try moving it side to side, if there is any appreciable movement you have bigger problems, if not put pipe wrench on yoke taking care that it won’t mar the ujoint seating surface, and hold or block it while removing pinion nut, this will take some effort especially with a breaker bar. Once the nut is off be sure to have a pan ready as you probably have way more oil in there than needed and you really don’t want to wear any, I can’t think of much besides skunk that lingers like the smell of used gear oil, the yoke may side out of it may take a slide hammer to remove, don’t lose the washer under the nut. Once the yoke is out inspect the surface for a groove , doesn’t take much of one to defeat the seal. Chisel and hammer to remove the seal or just hook it out with pry bar. Some will say to replace the crush sleeve, I’ve had good luck not doing this but the choice is yours, it will change how you go about re- ***embly.
I’ve added an arrow to your picture, it is pointing to where many 9” differentials have a fill plug. That is the height of the gear lube, little or no lube in the axle tubes.
The guys suggesting you only fill it to the level of where the filler plug would be on the center section, are right on. Then...if it still leaks, and after cleaning you determine it really is coming from the seal itself, you can fix that pretty easily, by removing just the five bolts holding the pinion support in place. Then you have to understand how the crush sleeve or spacer works, and deal with it accordingly. If you get that far, ask again and we can help you. (this involves measuring the pinion bearing preload before you loosen the nut on the pinion yoke).
I had a shortened 9" in a tubbed car. Factory housing, 4.10 gears, 31" tall tire. It had the factory vent in one axle tube. I was just getting off the highway, stopped at a set of lights when a guy pulls up beside me and tells me my car is spitting some type of fluid (lucky him being behind me ... sorry bud). I get home and the "mist" was coming from the rear end, out the vent. I ended up removing the vent, installing a threaded hose ******, adding a length of hose (1-1 1/2' long as I recall) and capping it with a tiny K&N style filter. Then hung the filter off the frame, well above the rear end. Never leaked again. A girlfriend from many years ago blew an axle seal (wow, that doesn't sound quite right ), then blew the other one shortly after the first was repaired. Turns out the vent was plugged solid causing the weakest link to blow. If you are filling to the bottom of the fill plug that someone installed on the back of the housing, you have way too much fluid in there.
I have also changed several without changing the crush sleeve.I have had to use a steering wheel puller to get the yoke off before
What Squirrel said! Get the oil level down to where it belongs, drive it and see if it still throws oil. If not, you're golden. If it does, then replace the seal. And after being overfilled all this time I'd be making sure that oil hasn't gottne past the axle seals...
Once you get to zero end play, tighten the pinion nut in very small increments between checking for rotational torque. It's very easy to go too tight and then have to start over with a new crush sleeve.
I use a spacer, so that's not an issue. With a "hot rod" third member, who knows what's in there now... so you really do want to check pinion bearing preload before loosening the nut.
You don’t need to replace the crush sleeve to do the seal, check rotational torque before taking it apart change the seal and when re***embling tighten to 2 or 3 inch pounds more then it was.
An old mechanic friend of mine, used to take a center punch and make timing marks on the end of the pinion and the nut, before removing the yoke. After the seal was replaced, he would tighten the nut, slightly past the mark.
This works however with most pinions being fine thread there is the potential to be off a full turn either way. The rotational torque doesn’t lie.
That is why you take it off by hand rather than with an impact and count turns. Those old mechanics who showed Marty and I the tricks knew a few things.
While I agree Marty that it seems hard to believe there is the potential. The other thing is being a lock but the pinion nut should be replaced. It takes less time to measure rotational torque then to count turns, I don’t need to be an “old” mechanic who has”tricks” to be able to do something accurately. Sometimes the old tricks work but aren’t the best way.
Back in the late 60's and early 70's I worked at a Lincoln-Mercury dealership. Ford had problems with ring and pinion noise and excessive differential case wear. We did a lot of 9 in rear ends. I went exactly by the book but it was hard to make flat rate. The old boy next to me asked me why I wasn't using an impact on the pinion nut. I told him that I was taught not to. He laughed and said he had been using one for years and never had a come-back. He came over and went through one with me and it took about half the time I had been taking. He had a quick way to set case spread and used an impact on the pinion nut. You just had to be careful once you hit zero end play. While I don't recommend it to anyone without a lot of experience, I've been doing it for many years with good results.
Or maybe you're just a bad counter.... I can count to 20 1/2 using all my fingers and toes, and with my pants down to my knees!
Curious, since I’ve only had two 9inch rears, but I’ve never noticed one with a fill plug in the housing and both I had the fill plug was in the boss shown in the pic above. What years/vehicles had a fill plug in the housing?
Well...I guess I always suspected I was over filling it. Just old habits from always filling to the port. Oddly...lol...it always seemed to "self level" back down to arond the bottom of the axle tubes. I'll clean up the mess, figure out a dip stick and keep a close eye on it. Thanks for reaffirming my ability to miss the obvious.
Lol. I remember I wanted to change the oil in my truck years ago. Asked my dad how to drain it , “do I have to take the 3rd member out”? “No just take the bottom bolts out and wait “. Then years later I had Currie make me up a narrow housing, still no fill plug in it. But both had the fill plug in the 3rd member location, so I (lack of knowledge) thought it odd yours doesn’t have one. Guess I’m just to used to the General
Lol...yeah, I guess my brain just kind of limped along thinking there must be a reason they eliminated the diff plug and put the fill plug up so high..or maybe it was me that was high..
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