leaking from differential - Dodge Dakota Forum

Subject: leaking from differential
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2002 3.9 5spd 2wd 3.55 gears

i'm not sure what the seal is called. i've got gear oil all over the place under the bed of my truck. It's sprayed all over the side of the fuel tank and all on the under side of the bed. It looks as if it was spinning! Its wet where the driveshaft hooks into the differential and i'm quite certain its coming from that seal. what is the seal called and can i replace this myself. I checked the fluid level for the gears and i can still feel it when i stick my finger in the fill plug hole so it's not real low. It's it safe to drive the truck as long as i keep my eye on the fluid level. Not sure when i'll get around to fixing it let alone if i can fix it myself. I'm flat broke and no way can i take it to the dealer. I stopped at Advance auto and they said they couldn't find the anything that looked even close to the seal that goes back there. they said it might be a dealer only part.

sport02
Dodge Dakota
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7/21/2007
18:33:37

RE: leaking from differential
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ok, it is called a pinion seal, did some research. Is that the only thing that gets replaced? Looks like you need a gear puller to get the yoke off. what size nut holds the yoke on? then i guess just pry the old seal off, sand and clean it up a bit, tap the new one back on. should i put anykind of high temp sealer?

sport02
Dodge Dakota
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7/21/2007
19:54:46

RE: leaking from differential
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apparently there are two sizes for pinion seals. theres an 8.25" and a 9.25". where would i find the size for my truck. also, will i really need a chain wrench to hold onto the yoke flange when taking off the pinion nut? won't the weight of the truck be enough to break the nut free? i really appreciate everyone's help if they can help me. thanks

daddio
Dodge Dakota
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7/21/2007
21:18:50

RE: leaking from differential
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you've probably got the 8.25" rear. check the inside of you glove box lid. it should have a sticker with some info including the rear end info.

also, spend 20 bucks and buy a Haynes or Chilton repair manual before attempting soemthing like this. i don't think it's as simple as pulling the yoke out and changing the seal. i haven't had the opportunity of tearing a rearend down but i do know if you don't know what your doing you can really screw it up.

and depending on miles and how long it's been leaking you may want to change the pinion bearing too.

dakota49
Dodge Dakota
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7/22/2007
20:39:29

RE: leaking from differential
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Sport02, I just looked it up in my Haynes manual.
It says to punch mark the pinion, nut, and yoke.
You should count the number of threads on the pinion as well and write that down.Then you need to use a torque wrench to see how much torque it takes to turn the pinion, write that down as well. You may need to use an inch pound torque wrench for an accurate measurement. You maybe able to use a big pair of plyers to hold the yoke, or use the parking brake. Remove the nut, then the yoke. DO NOT HAMMER, OR PRY ON THE BACK SIDE. You may have to use a 2 or 3 jaw puller to remove the yoke. Then remove the seal, clean, install the new seal using a seal installer, or a big socket.Also put some non-harding sealer on the splines put back together and check that you have the same number of threads on the pinion as when you took it apart, and recheck the torque to see if its the same as before you took it apart. I think its pretty much straight forward, so if you take your time you can do it in just an afternoon.
Good Luck
88 3.9 5 speed 4X4
Dakota49

sport02
Dodge Dakota
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7/22/2007
21:28:37

RE: leaking from differential
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yeah i was actually looking in a manual at pepboys but it wasn't a Haynes. they actually give you a torque setting for when you retighten the nut but i don't know how they can know that without checking it first. i would assume the rear of truck needs to be jacked up. I am also assuming that you just use a torque wrench on the nut and make like your going to tighten the nut and take the torque reading when the back wheels actually move. this is the torque spec that you re-torque when putting the nut back on, correct? I only have a 3/8 drive torque wrench not sure how high the torque readings go. after you get all this then punch mark everything, remove nut and use a gear puller? I am going to call the dealer and see how much this job will cost from them. I wouldn't think that it would take more than a half hour from a mechanic thats done it before and on a lift. I'll check some other shops too. I'm sure i can do this but i don't have all the tools and buy the time i would buy them maybe i could have paid someone to do it.

dakota49
Dodge Dakota
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7/23/2007
13:46:29

RE: leaking from differential
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I didn't check the torque when you put it back together, the reason you want to check the torque after you remove the drive shaft is so you will have the same, or close to the same torque to turn the wheels as when you take it apart. I'm thinking it shouldn't be more than about 7-18 inch pounds. I wouldn't go to a dealer, I would find an independ shop and see what they say. Maybe an hours labor, plus parts, seal and gear oil to top off.
I do most all of my own repairs so I don't mess with shops. I've had a few too many rip-offs.
When I rebuild an engine I try to find a good shop for the machine work, that too can be hard also.
Good Luck,
Dakota49

sport02
Dodge Dakota
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7/23/2007
22:41:55

RE: leaking from differential
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well it just ate away at me thinking about having to take the truck to the dealer or anyone else after i found out the part was only $15 plus the gear oil and frict.modifier. I knocked off work today, went to dodge dealer and got the seal and oil and rented a large torque wrench and gear puller from autozone. Everything went great, bit of a pain though without a lift and a real bugger getting that old seal out!! I did everything just like you said (dakota49). I also knotched everything for reference point when putting all back together. i checked the torque with wheels off and drums removed and driveshaft off but only had foot lbs which barely even registered 2 ft lbs if that. I put the seal on and put everything back together but noticed i couldn't get the notches to line up exactly where they were without having to much drag. they are darn close though! I'd say if anything the pinion nut might be a tiny bit tighter than before as my torque showed just slightly higher when turning the pinion. I did not want to loosen the nut as i read from TECHAUTHORITY.COM not to loosen if too tight, you would actually need a new washer but now dodge says the washer and nut are all one now. I thought the concaved washer was a better idea because it gave you more room for adjustment but now with a flange nut how do you do that? the old washer looked fine so i used it again. Honestly, it didn't feel that hard to turn and the nut was tight and everything was smooth and not play so i put the drive shaft back on. also drained the remainder of oil that was left in there and refilled with new mopar synthetic along with the friction modifier. the leak is gone thank goodness! it took a little over 4 hours for me but i took my time. turns out i didnt even need the gear puller, the yoke (looked like mini fly wheel) just slid right off of there real nicely, it's not pressed on.

sport02
Dodge Dakota
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7/26/2007
01:21:51

RE: leaking from differential
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well all is well so far, leak is definately gone! I can't help but keep questioning myself now as to whether i may have made that pinion nut too tight. there is no noise or anything grinding, etc. there does seem to be a little bit of drag that i'm feeling with the truck but it was already kind of doing this before i replaced the seal it's just now it's making me think the pinion nut is too tight. the truck coasts nicely but not accelerating so great. I did have the NGK fr5's in but i was getting hesitation with them and pulled them and they were white. I put the champions back in and they are burn light tan. is there a learning period when you replace plugs from one heat range to another? could this be my hesitation?

dakota49
Dodge Dakota
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7/28/2007
16:21:24

RE: leaking from differential
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Hey Sport02, glad to hear you did the job your self, and don't worry about everything lining up, you said its "close" and just a little more torque to turn the yoke so I wouldn't worry about it. Sounds to me like you did everything right.
As for the plugs, Larry says it can take up to 1000 miles for the computer to relearn what changes were made, especially when you are going to something a little more efficent. Mine is an old 88 and when I changed plugs it ran better right off, and I got better fuel mileage right off as well. I am using the Halo's.
Good Luck
DAkota49
88 3.9 5 speed 4X4 3:55 gears

dale
Dodge Dakota
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6/18/2008
13:38:53

RE: all apart
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1997 dodge dakota sport 4x4 5.2

hello i have a bit of an issue?
my girl friend was driving my truck and the drive shaft fell out lol.

well it happend because the pinion bolt fell off i know wow. thats crazy but it happend and now i need to know what the torque specs are i did tear the hole rear diff apart and know i have to put it back together and ive never done this before but i cant afford to take it to the other people cause they want to steal from me.

sport02
Dodge Dakota
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6/19/2008
01:14:04

RE: leaking from differential
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chilton or haynes manual. also could call the dealer but they are real pricks about looking up specs for do it yourselfers, stands to reason. they also use a website they pull technical info from. they pay a yearly subscription for it. if is available to anyone per 24 hour time periods. I think it cost like $25 or something like that and you can print all the stuff out. call the dealer and ask for the website. honestly, just buy a repair manual and have the info forever.

Vernon
Dodge Dakota
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7/08/2013
04:09:34