Oil/Grease Coming From Somewhere

[psa55]

Hey All, I found a few drips of oil/grease on my driveway, but I'm not sure how to address where it is coming from. I've attached a pic with everything labelled as best I could to identify where the problem is. If you can see what is causing the issue, I would appreciate the help. My guess is a seal/gasket of some kind whatever seems to be coming into the front diff. I've become okay at turning some wrenches, but still can't identify everything I'm looking at unless I've had to deal with it.

Any help would be appreciated.

I was worried after the new exhaust manifold went in, that the tranny dipstick gasket was leaking, but that appears clean and dry as best I could tell around the pan in its location. On the another note, I had a idling issues on startup as mentioned in a thread a week or two back, and spent the days cleaning up a few items... Cleaned the MAF Sensor, removed and cleaned the throttle body, new MAP sensor (whitebox closeout on right now at RA) and a new CPS (been meaning to get to it, since the CKP left me stranded for a week last year, waiting for parts).

 

[Mooseman]

What year is your truck? It could be the first year defect of the front diff that caused leaks. Can you smell the oil? Smell like gear oil?

 

[psa55]

Truck is a 2008. Got 291K kms on it.

I took a look at a diagram and it appears to be a shaft coming in the back of the differential. Possibly a pinion seal? If that's the case, from what I can see, it seems that would be a huge front end teardown to replace it, but that is a complete guess.

It looks like oil on the driveway and feels like oil on my fingers from where it was dripping. Can't say that I smelled it.

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[gmcman]

Could be the grease from the CV boot. The diff would have oil but could pick up road grime.


I'd look into the CV boot first.

 

[Mooseman]

Might be worth it to give that whole area a good cleaning with a high pressure washer to see where it might be coming from. I have found this useful on several occasions. Also check the oil level in the diff. If it is significantly down, then the diff would still be suspect.

 

[ThatOneWhiteTruck]

i can’t really tell from that pic but maybe the axle seal idk when mine was bad it leaked gear oil

 

[psa55]

I figured I better check that diff fluid level... took a pic and its full! Bad news, still not sure what I'm hunting. Didn't get a chance to clean everything up well, but hope to in the next few days. From the pics, you can see the CV axle seal (replaced last year, new fluid) seems okay, where the diff meets the oil pans seems good, as does the pinion seal/driveshaft end front the top.

Nothing in the area jumping out at me at all as a source. Will have to dig deeper.

 

[psa55]

Did an oil change tonight and had the TB on ramps. Easy to slide in for a better look. Good news is that I think I found. Looks like a pinion seal? Where the 4x4 driveshaft goes into the back of the diff. Entire bottom of seal is wet with oil. Top half looks dry. Can this seal be changed while on the TB? Driveshaft come out, pull the seal and R & R everything?

If it can't be done on the vehicle, I know there are a couple how to's on removing the diff from top or bottom, if necessary. I'll be a few months before I'd have time to do that and will just check and top off often, for the time being. Was full in the previous post.

 

[Reprise]

Yep, that's most likely a pinion seal (my rear is leaking like that, too).

And (assuming that's the front diff), you should be able to leave the diff in place and do it where it sits. I haven't done a front diff pinion seal, so I can't give you "here's what worked for me" (tbh, I started this post thinking you were talking rear diff, but that's got to be the front one.)

A lot of people let them stay like that for a long time before changing, in the rear, at least. So if you check the fluid and it's not off by much, you can top off and it should be fine while you do the homework of 'how' to do the front one and get your parts. You'll need a seal, and a lot of the time, a new pinion nut is called for, as well.

On the rears, if you're doing this repair, the nut is torqued a little more lightly if the bearings behind it are staying in place, vs. putting in a new bearing set. You'll also want to put reference marks on everything you remove -- driveshaft bolts (11mm at the rear), the bands / hoops holding the shaft & U-joint to the yoke, etc. Sharpie makes a grease-type pen with white 'ink', which is great for this; you can get them at your local hardware.

For the seal itself, I'd get a Timken or a National; AAM or AC Delco would be next choices (and their seals are made by National or Timken, so whichever is cheapest.)

If there's a pinion nut to remove, pay attention to how it's to be retightened, with existing bearings vs. new bearings (which, hopefully, you won't need to worry about).