2014 Sierra 1500 - Front diff leak

[Neil G]

I crawled under my truck today and found there's some leaks along the front diff line. I'm not sure what it is. Can anyone please help me identify what it is. It's the small yellow part in the picture. The front diff itself is also kind of wet around the fill plug and drain plug area  but no drip. Just like damp wet.

 

2014 Sierra 1500 SLT 4WD

Thank you!

 

[rav3]

The yellow part looks to be the front diff. locking mechanism. From what I see, there's a very small amount of "seepage & not a leak so to speak. I think you're good.

[CamGTP]

I bet if you cleaned it all off with some degreaser it would take years to look damp again.

[Neil G]

I proceed to change the front diff fluid. I put in Mobil Delvac 1 Synthetic 75w90 oil. The front diff is now whining. Is synthetic oil not compatible with it? I read somewhere that a vent connector needs to be replaced if using synthetic oil. It was for older model though so not sure if the 2014 model is the same?

Edited December 11, 2023 by Neil G

[rav3]

Synthetic GL5 gear oil is fine for front & rear diff. How many miles on it & did you fill it up?

[Neil G]

3 hours ago, rav3 said:

Synthetic GL5 gear oil is fine for front & rear diff. How many miles on it & did you fill it up?

It has 113+ kilometers (I'm in Canada so it km). It's filled I think. I opened the fill plug again and it started dripping oil. I noticed when I opened the fill plug, there was a Sssshhhhhhhh sound like air coming out from the fill plug. Could it be the vent is clogged or maybe it's over filled?

[rav3]

Sounds like tge vent tube is bad somewhere. Shouldn't have pressure like you mentioned. That will make it leak.

[Neil G]

Thank you!

I'll go and check the vent tube. I'll drain some more oil as well, like open the fill plug and let it drain until it stops.

 

[rav3]

The vent tube should be on the drivers side under the hood.