While installing my brand new Tanabe Medalion Touring mufflers last night, I discovered an oil/fluid leak on the passenger side of the of the rear differential where the drive shaft housing bolts to the rear axle side flange.

I cleaned it off last night to see if it would reoccur. Took the G out this morning to burn in the new mufflers and when I arrived home I found A LOT of oil/lubricant again at the same place. It was also getting thrown onto all things in the immediate area (including the exhaust pipe just below it).

I called my selling dealership's service department. They suggested getting it towed since it was leaking onto the exhaust pipe. I had the G towed to the service department this afternoon. They were able to put in on the rack right away.

The rear diff was not low, nor could they find any source of the fluid/oil. The CV joint was not leaking nor was the rear diff. They cleaned it up and took it on a test drive and there was no more leak.

I drove the G home (45 miles one way) and checked it again when I got home. Still no leak. Very weird.

 

Could it have been a little overfilled and spit out of the breather? Was it abnormally hot out when you noticed the spilling?

 

No the outside temp was in the 70s. The service department claims it was not coming out the breather, but I cannot be totally sure. Nothing about this really makes much sense (yet).

 

maybe you ran over something

 

Anything is possible, but running over something with an oil/fluid and it just happened to land right there. I guess stranger things have happened to me.

The other odd thing is that I observed the "leak" twice. First the night I installed the Tanabe Medalion Touring mufflers and then the next morning.

It's in the "wait and see" category now.

 

they put glue over it to plug it lol

 

The leak has returned. I took the G37 back to the service department. I drove it in this time. They set me up with a loaner G35 sedan while my G37 is in the shop.

Let's see what they [don't] find this time.

 

The update from late Tuesday was that no "major" leak can be found. They confirmed the rear differential oil level has dropped since they filled it last Thursday. They have contacted the Infiniti tech support line to ask for insight into this problem. They believe they're going to replace the passenger side differential seal, but there has been no response from the Infiniti tech line as of yet.

 

Three days later and still not fixed. It took them two days to decide to put some leak test dye into the rear diff oil. Why wasn't that done on day one.

They claimed no new oil could be found after three days. I pickup my G37 and drive it home, and there's oil on the tips of the rear diff axle flanges (on both the driver's and passenger's side).

I'm taking it back in tomorrow morning, and I've requested that we put it on the lift so we can all look at it and agree that there is oil present. I've marked the top of one of the bolts near a one of the larger "oil spots".

This is getting real old real quick....

 

I took the G37 in twice on Friday. First time was because it became wet again with oil or oil like substance after driving it home on Thursday. They cleaned all parts off with brake cleaner. It was "dry" when I left the service department the first time on Friday.

I drove the 43 miles home and it was wet again. I called and then drove it back again to have them say "I don't see a leak". The fact that oil was present on the parts he just cleaned off two hours before is not enough for them to call it a leak. They need to see it in the state it was the week before (extremely wet with oil).

Needless to say I was "upset" with this "word play" (leak vs. wet vs. residue) they're now engaged in with me. They won't call it a leak until they see that it has a similar amount of oil on it like they saw it with last week and I have to drive it "enough" to make it that way before they will do anything.

I called Infiniti and I opened a complaint because the way they are handling it is .

 

Infiniti called back yesterday to state that the service manager would be giving me a call.

The service manager did in fact call and we discussed the issue. He was very nice on the phone and he stated he would drive out a loaner vehicle and pick up my G37 to have his shop perform further work on this issue.

This morning the service manager arrived in a nice EX35 loaner. I had him look under the G37 and examine the area in question. The driving I've been doing the last several days produced a nice amount of "oil" on the passenger side rear axle flange. He rubbed his hand on this part and he had a good amount of "oil" on his fingers. He agreed that it is definitely leaking somewhere and that it looks more like rear differential oil than anything else.

We'll see what they come up with this time......

 

The leaking oil was not from the rear differential because it did not contain any of the "leak dye".

It appears the CV joint side of the rear axle flange was the "oil source". The CV joint lube had broken down into the thick grease part of the lube and some thinner "oil". The oil then passed through the CV joint rear plug and then out where the CV joint and rear axle flange are bolted together.

The CV joint lube was discounted as the leak source in every previous conversation since its lube is much ticker and darker than what was leaking out.

Well, now we know better.

The service manager drove my G37 back to my house. I took a good look at all areas around the rear axle flange (both sides). I could not find anything "wet with oil". If I can still state that two weeks from now, then I'll consider this resolved.

 

Did they do anything to fix the leak or simply clean the joint lube off? I have this problem on my 2012 G37. Black so not rear diff fluid or the yellow bushing leak problem.

 

The leak was the where the CV joint bolts onto the drive axle. The CV joint grease broke down and the light oil from the CV joint grease leaked out of the CV joint.

They replaced the CV joint grease and then used a sealant on the CV joint mounting surface.

That car never had another leak in this area.

My current 2013 G37x has not had this problem occur (yet).

 

Thanks for the reply. Mine is a 2012 37x with 17k miles....the leak is in the front of the pumpkin but the pinion seal is dry...strange. It looks to be oil but when I put some from the drip on my fingers it is almost brown and thicker ...like grease(leads me to believe my problem is similar to yours). I sprayed everything off this weekend to see if it comes back...