GMC/Chevy SUV guys – chronic differential leaks?

Was out in the garage doing some work on Wednesday night and uh-oh. ANOTHER black oil spot on the cement, right below where the differential for my 2013 GMC Acadia would normally be. Again!

Looked under the vehicle and yep. Diff is shiny with oil. Trough to tell, but looks like another leak where the driveshaft enters.

If this IS the same thing it’s been the last 2 times this has happened, I’ve got a bad bearing in the diff and then wrecked seals. This has been done twice before, once at 54k, once at 75k. Guess what I’m at now? Would you believe 95k. Yep.

Is this a known fault in GMC Acadia and possibly the Chevy Traverse where this is always going out? Or is something not being done right here? It seems impossible to me that this is bad luck if this is the same issue. I’m also a little nervous because when I had this fixed the first time, the dealership either forgot a seal or damaged it on installation and it was peeing oil on my garage floor 15 minutes after I got home. I was back in the shop the next day for a second try at the fix and I wasn’t real damn happy about it.

Both fixes have been done by the same GM dealership and the truck is now in the same shop for another try. Diff fluid was changed at 50k, 54k, 75k, and I’m betting it’ll get changed again today, so this is NOT a dirty/contaminated fluid issue.

What’s going on here? Anybody with any insight on if this is a chronic problem and if there is a better fix? Or is this a problem that could happen once but should never happen 3 times in 60k?

Grouse

Seems excessive for sure. How is the alignment between the drive shaft and the differential? Something is causing the failure. Any damage on the drive shaft where it slips into the differential?

Trade it in.

Driveshaft aligment or bad CV joint on driveshaft will burn out seals.

Also check that the vent tube is working properly. As the fluid warms up it can create pressure inside causing some fluid to weep.

The vehicle has never been in an accident, so I’m not sure where misalignment could come in unless it was a bad factory build somehow. Would expect the mechanic would look for and recognize driveshaft damage, but as always the problem is knowing whether I have a mechanic working on it or a parts changer working on it? Very difficult to know.

Won’t be trading it in. Mrs. Grouse is the chairperson of the Budgetary & Finance Committee and for reasons I don’t quite understand, I’m considered a “non-voting advisory member”. Chairperson says new is a no-go.

gixxer01 wrote:

Driveshaft alignment or bad CV joint on driveshaft will burn out seals.

Can driveshaft be re-aligned on these vehicles?

Is it possible that the 2 times before they replaced seals and bearings, but did NOT align the driveshaft?

Thanks, this is what I was looking for.

Grouse

Grouse, I don’t have an answer for you on whether its cronic or not, but don’t ever expect a mechanic to look for that type of detail regarding alignment.
Yes, there are many good mechanics out there, but there are about 10 others that just do the bare minimum. I would suggest it to the service tech and make sure they provide measurements, etc to you upon completion and a comparison to what spec is. Only way to have a bit more faith in that they actually do their job.

BTW, my wife has a 2009 outlook which is the same vehicle. Her’s is AWD, not sure if yours’ is or not, but we have not had any diff leaks with it as long as we have owned it and have put on over 35000 miles on it since getting it. Bought it with 95000.

Rear diff or front diff? Any vibration felt? Grinding or humming noise?

I can tell you that if they rebuilt the diff there is a good chance they didnt set it up properly. To much or too little pinion bearing preload can cause a bearing to run hot and cause seals to fail.

I have redone my 05 Grand cherokee rear diff 3 times until i noticed that the u-joint had flat spots. Caused just enough vibration to wear the seal and eventually the pinion bearing. About 25k miles between rebuilds.

As for aligning, there really is no way to align them. Typically if they are out of alignment it is due to worn out bushings in the suspension that cause excessive driveline flex. Transmission mounts, transfer case mounts, etc. Not sure of the acadia, but possibly differential mounts if it is not a solid axle rear end.

gixxer01 wrote:

Rear diff or front diff? Any vibration felt? Grinding or humming noise?

Thanks for the reply.

It’s the rear diff on AWD 2013 Acadia SLT. No felt vibration or noise and it hasn’t been leaking long. Mabe 1/4 cup fluid found on the garage floor and since I work out there a lot, I doubt it’s been 2 weeks or I’d have noticed it.

You think I should ask them about the U joint and if it was inspected? This is likely my last in-warranty try at this repair, so I’m very concerned that they get this right this time. Being this is the third time, it’s pretty difficult for me to believe that they aren’t missing something.

Grouse

I’m sure it’s of no relevance being the rear end is 100% different, but my 2006 Silverado would eat rear pinion seals like it was candy (every 5-10k). The problem was a bad yoke…replaced it with a new one that i drilled for a Zerk and it was good for 50k before the motor went and I sold it. Never thought it could be the yoke since I never heard any of the clunking associated with it, but it was.

I would definitely have them check the ujoints. Ask if they can check the balance of the driveshaft too. You would probably feel that though.

I tend to stay away from dealerships and have never owned a vehicle with a warranty, but i would make sure you get them to write something up being this has been an ongoing issue within warranty. I have heard that they can still warranty work outside of the warranty period if you have some sort of document from the dealership regarding this ongoing issue.

OK, dealership just called. Here’s their verdict.

Fluid way overfilled the last time they did it. Fluid leaking out overflow vent due to diff heating up. No other leakage found.

As you can guess, I’m a little suspicious of this diagnosis. Why would an overfilled diff start leaking fluid out the overflow 20k miles AFTER it was overfilled? And in the winter?

So now I’m going to have to watch this like a hawk. I’ve got the cardboard box with white paper towels in it already.

I guess we’ll see how it goes, but I’ll have to grease up the wheels on the creeper because I’m going to be under this thing about every 2 days looking for leaks.

Grouse

Depends on where the oil was on the diff. Typically a bad seal will be visible by a line of oil slung around by the spinning driveshaft and the bottom of the diff coated in oil. Take a look and see where the vent tube terminates and where the oil originates from. Remember, the origination point would be above and in front of where the oil stain is found. Fluid runs down and to the rear while driving.

I have never seen an acadia diff, but i have never heard of the vent being called an overflow vent. It is only there to vent pressure. Dont know how they could overfill a diff that much. Unless they filled the diff from the vent.

gixxer01 wrote:

Ask if they can check the balance of the driveshaft too. You would probably feel that though.

This has been a relatively large problem on vehicles. I saw a video on youtube showing one out of balance and it was ridiculous!
Depending how bad it is it might just come across as a tire out of balance, but you should notice it.

TheFamousGrouse wrote:

OK, dealership just called. Here’s their verdict.

Fluid way overfilled the last time they did it. Fluid leaking out overflow vent due to diff heating up. No other leakage found.

As you can guess, I’m a little suspicious of this diagnosis. Why would an overfilled diff start leaking fluid out the overflow 20k miles AFTER it was overfilled? And in the winter?

So now I’m going to have to watch this like a hawk. I’ve got the cardboard box with white paper towels in it already.

I guess we’ll see how it goes, but I’ll have to grease up the wheels on the creeper because I’m going to be under this thing about every 2 days looking for leaks.

Grouse

I have seen this MANY times in most all GM 4×4 vehicles….Any one working in a dealership should know NOT to over fill those differentials,due to pressure it will push fluid out anywhere it can and also states in manual not to over fill,,…fill until it just starts to come out and let it drain until it quits, then install plug….

The times I did replace a worn yoke it was when the vehicle was driven either on gravel roads alot or in mud and such.

Not sure over filling is your problem FG but you never want a diff over filled. You are actually better off just a tad below the the fill hole. Also make sure vent is not plugged.

Diff leaks are not a known problem on these vehicles, however timing chains are and they usually go at around 100k miles.

As a former owner of the same vehicle but in a 2012 please get out now! That vehicle will $1000 you to death.

It is hard to sit on here and tell you what is wrong with the vehicle but the first things to look at is what the dealership told you, over filled and vent plugged. if you have just been making short trips since last fixed may not have gotten warm enough to leak and as the weather is warming up it may have gotten warmed up and start leaking. Good luck with it and keep up posted.

Don’t they fill thru the plastic/rubber plug, about a 3/4″ hole ? Almost impossible to overfill unless doing on purpose, really quick hands.

Thanks for all the replies, guys. It’s good to know that overfilling is at least within the realm of possibility.

What has me nervous about the whole thing is WHY NOW? The last seal/bearing replacement was 20k miles ago, at which time the changed the fluid and this is where that overfilling had to happen.

So now 20k miles later, in the winter, it gets “hot” and starts to overflow? Again, not impossible as I was heating her up pretty good with some deep snow action spinning my way into my hunting property back in January, but I’m still not totally on board with this idea.

Basically, I’ve got a box lined with paper towels under the diff now, so if there’s one drop of fluid in there, she’s going back in. Honestly, I hope the dealership is right on this, but I want this fixed while under warranty.

Grouse

steveo wrote:

As a former owner of the same vehicle but in a 2012 please get out now! That vehicle will $1000 you to death.

Yes timing chains are a problem in these and the v6 Equinox/Terrain models. Most of the problems come from people who are not changing the oil often enough and/or running them low on oil. I know the manufacturer says you can run 7500 miles between LOF but most vehicles will be at least 1 to 2 quarts low on oil by then. You are starving the chain of lubrication then. Most people never check the oil level. It is just put gas in it and drive it.
Most outdoors people (hunter/fisher people) take better care of their units than any other group of drivers. Just my opinion.

Is the vent plugged?

Not the same vehicle but I had a leak on one of my Dodge differentials and in the process of replacing the bearing the mechanic scratched the bearing seat and it wasn’t long before it started leaking again. I took my truck to a different mechanic and he identified the problem, showing me the damage likely caused by the first mechanic trying to get the bearing out with a screwdriver. Once fixed correctly, it has never leaked again.

Ford had a few years where the driveshafts were made to long for the f 150. Rear ends would only make it 30000 miles. They replaced 2 in my truck and then it went out after the warranty period. They never really fixed the issue they just put in brand new axle assemblies each time. It happened right after they switched parts manufacturers and had China making those parts.

I have a couple suggestions as to cause that may be overlooked. First. It is possible that the seal was not installed properly. Gm has and provides specific tools used for installation of seals. Good technicians find and use the proper tools. Bad techs use what ever they can find to pound it in. So it’s possible it was not installed properly. It also could have been hit by the axle splines when the tech was re installing the axle.
It is easy to overfill the rear dif on these. It is also easy to underfill. You have to put the fluid in with a machine and the machine pumps faster than the fluid can spread into the dif. So you have to let it sit for a minute and let it run out and settle a couple times. Should be even with fill plug and a small trickle of fluid come out of fill plug when removed.
I also recommend replacement of the vent as this often goes overlooked for the root cause of leaking seals.if it is plugged or obstructed, pressure can’t escape and can cause seal failure.
I was wondering if the vehicle feels like it binds at all on tighter turns?i would compare it to driving in 4wd on dry surface but not as aggressive. I’ve replaced electric clutch on these in the past where fluid has leaked out of the pinion seal and got into the torque tube where the clutch sits and when this happens the clutch won’t release properly. This can cause the dif to overheat.
The 3rd is the tires. What condition are the tires in. Awd vehicles all the tread should be within 3/32” of each other. If they are not they can load the dif up and cause gear ratio issues. This can not only damage the rear dif, but also the transfer case so I would also check the fluid in the t case for metal or evidence of failure.
The last thing would be worn bearings in the rear dif. This is the least likely scenario as they really don’t wear out and if they do there will be other evidence. When they wear out on this style dif it will affect the backlash and preload in the dif and there will usually be a lot of noise associated with that.
I hope this helps