I also would be curious if anyone has experience in doing this. My axle seals were leaking at 18k miles and were replaced on warranty.

For as long as GM has been making diffs, I sure would think that they'd be able to make vent tubes that wouldn't clog up. Am I right?

 

Might be helpful, pics of vent itself in 3rd link in first post:

ATS differential fluid change and vent clean

I originally did the diff fluid sometime after I got it used w/17k on it in 2014. Fluid didn't look too bad, but it had a disturbing amount of crud stuck to the magnetic tips on the fill & drain plugs, like a thick paste. Probably break in material worn off the gears. So decided to do it again...

www.cadillacforums.com

 

I crawled under my 2.0T. See picture below, I believe this is the vent port. I was trying to determine the socket size for removal. 15mm is too small while 16mm fit loosely. I'll probably order a replacement piece before I attempt to remove it. It's a tight space so I am not even sure if a wrench tool will work under that space.

 

Yeah, thats the vent plug. I used a 16mm wrench and it worked well. But it was not possible to work with a torque wrench (the plug needs 30 Nm).

 

ahs2M2,

Thanks for posting and that it the vent. This may be one of the places where a ratcheting box wrench makes life a lot easier. I have a set of these in SAE and metric and although I don't use them that often, when you need them they really work well for quickly removing fasteners where a regular socket/ratchet won't fit and they are much faster and less aggravating than using a standard wrench.

These clean up easily so you shouldn't need a new one, WD-40 works well as a solvent and you probably already have that on hand. You don't really need a torque wrench for this because it isn't something that is sealed or load bearing/fastening so you just want it snug enough not to self-loosen. As soon as it starts resisting further turning, stop.

It appears that at one point your vent, vented a lot of fluid or vapor. In normal operation these are normally just an air vent with some vapor from the lube also venting mostly with new lube. I suspect your diff might have been over-filled at some point to vent the diff lube. In typical operation, air is vented when the diff/axle assembly heats up and drawn back in when it cools. The only purpose of the vent is to make sure that the assembly is never under pressure or vacuum and to be in a location high enough that water won't enter in normal operation.

Rodger

 

Thanks for the great suggestion. I was looking online for metric ratcheting wrench set to add to my tool collection but they all don’t come with size 16mm. There is a 15mm then 17mm. I wonder why.

 

https://www.amazon.com/HORUSDY-20-Piece-Ratcheting-Wrench-Ratchet/dp/B07K73QN1Q/ref=pd_di_sccai_4/137-6743075-7591765?_encoding=UTF8&pd_rd_i=B07K73QN1Q&pd_rd_r=34159787-5ece-4115-b1f9-a03d93249aeb&pd_rd_w=MNh3W&pd_rd_wg=j2tht&pf_rd_p=61ce50cf-2379-4458-9044-fa8b402c702d&pf_rd_r=2KN79HMP2170CSRG4K9Y&psc=1&refRID=2KN79HMP2170CSRG4K9Y

Yes, 16 mm is pretty unusual. Years ago I worked on my Volvo and needed a cranked 22 mm wrench for the strut nut. My dad almost has every nut or wrench, but this damn thing was missing. Don't know why the engineers stick to the common sizes.

 

They may not all be 16mm. I tried that one on mine and it was too big for my vent. I believe it was 9/16th. Mine's a 2013 with the LSD.

 

Sergio, what was the part number for your LSD diff vent? 23156298 is not it (although if someone wants that part no., I got one!) and I'm having trouble finding the proper vent.

edit - I think it is 22929622. Here's hoping that's also what you got!

 

Reaching wrenches are NOT for breaking nuts/bolts loose. I have 2 complete sets of SAE/Metric. I have both Harbor Freight and Sears.
The HF set has 3 adapters to allow you to use a socket, assuming you have room.

 

Thanks for the replies. Box wrench from Amazon came in today and I took the vent port off with the new tool. Well, it doesn't look like my vent port was clogged at all. Maybe the blown axle seal on mine wasn't caused by clogged vent port but factory fluid over-filling.

Few takeaways from this
-16mm or 5/8 to size wrench to remove. At least on 2.0T without LSD
-GM part number 23156298. I bought a spare so I can do a direct swap and clean the other at my leisure
-I was able to perform the task without raising the car but it will definitely give you more elbow space if the car is raised.

 

Thanks for the replies. Box wrench from Amazon came in today and I took the vent port off with the new tool. Well, it doesn't look like my vent port was clogged at all. Maybe the blown axle seal on mine wasn't caused by clogged vent port but factory fluid over-filling.

As I noted in my recent posting on the vent, I am convinced that clogging is not the problem, but rather it simply requires too much pressure to open the valve and vent. With all of the reported leaking axle seals, I believe fluid over-filling is not the cause either. I bought a replacement and took it apart. it's a simple design - a round rubber disc, a round metal disc, a light weight spring and the dust cap. I should pop open easily but for some unexplained reason it doesn't. I shortened the spring length by half and it opens easier but it still takes a fair amount of pressure to open.

 

Take a small/ flat tool and cautious lever it off. Underneath that rubber plate is the spring.

 

I have taken mine off several times and I am pretty sure I would have noticed if the threads were reversed but maybe not.

The surge tank in my 2018 GMC diesel uses reverse threads for the top always sealed cap which is very noticeable to me. Perhaps someone in GM did this as a safety measure to reduce the odds of someone who shouldn't from removing the cap from a hot, pressurized cooling system. The pressure venting cap on the lower side of the overflow/recover portion of the tank has normal threads.

Rodger

 

How do i find out if i have a LSD or open? And what fluid would i need to do a flush?

 

If you have a manual transmission or Premium trim, you have LSD. Fluid PNs in this thread:

ATS differential fluid change and vent clean

I originally did the diff fluid sometime after I got it used w/17k on it in 2014. Fluid didn't look too bad, but it had a disturbing amount of crud stuck to the magnetic tips on the fill & drain plugs, like a thick paste. Probably break in material worn off the gears. So decided to do it again...

www.cadillacforums.com

 

Tyvm guys

 

^he was saying premium AWD models do not have LSD, just the RWD ones.

 

I removed the diff vent on my 2014 manual Performance yesterday to look at it. I used a 5/8" box wrench, it was certainly snug on there but nothing crazy to break it free. Also it was not reverse threaded, nor did I need to jack up the car to do it. This was the first time I have removed the vent myself. It may have been cleaned when I had my axle seals replaced at 44k miles, never did verify that. I may be mistaken, but I thought I might have heard a tiny "hiss" when I unscrewed the vent...if that did happen I guess that could mean the vent was somewhat clogged and pressure was slowly venting prior to me unscrewing it enough, or the vent was clogged completely and this was pressure that had built up. I have no leaks right now, diff is dry.

I looked through several threads here to try and take it apart to clean it, but ultimately I did not feel comfortable trying to pop the cap off with it being the only vent I have currently. I ordered a new OEM vent off RockAuto for $16.53. When I get the new one I will be checking the diff fluid level & topping off fluid to top of file hole if needed, and installing the new vent. For now I just turned the cap some and pressed it up and down and some grime dropped out. Seemed a pretty decent amount.

I will take the old vent apart and mess with it a little, try cutting the spring as someone else mentioned to see if/how that changes tension. I would like to go to ACE Hardware and look for a barb with the same thread pitch and pair that with a hose, then figure out how and where to route the hose up into the bodywork and then back over so the end of the hose is facing the ground. Then figure out a way to mount the hose so it stays in the shape and location I want. Does that sound right? I have heard a few people say having a hose is a better solution and a surefire way to ensure venting the diff stays clog-free. But I'm not sure if the hose should just face up or if it needs to turn 180 degrees toward the ground.

 

Hi, Were able to install the hose on your diff?

 

I also found this stamping on the diff housing just below the vent hole. '40075260', which I assume is the part number. But just below it was 'REV B'. Would this stand for Revision B, meaning my car has a differential that was revised in some way when my car was built in April 2014?

 

Here's my take on all of this, and my ATS still has the original differential seals that have never leaked. If pressure builds up in the differential to where oil is forced past a seal, does this necessarily damage the seal? I would think the flexible lip that contacts the rotating shaft would spring back to normal after acting as a by-pass valve. If the problem can be repaired, why would the seals need to be replaced? I could be completely wrong, so someone correct me. I know a damaged or worn seal will always leak.
In my opinion, a short rubber hose with a filter would work better as a vent, as long as it is positioned to where it could not let water in.

 

I agree but the problem is once a seal is leaking you don't know if it is a faulty seal or pressure or if once a seal leaks if it is more likely to leak going forward. Unless something changes like removing the pressure or replacing the seal it will continue to leak so your questions are correct we just don't know. When you take it to a repair shop with a leaky seal the best option they have is replace the seal. You personally could continue to refill it or try to solve the problem with changing the vent some way but a repair shop isn't likely to have a customer that understands or wants to bother with it.

So, you guys are saying that replacing the seals may not be necessary, and by doing so is like treating the symptoms and not the core issue, i.e. the vent. Could it be that by fixing a clogged vent the leaking will stop and all will be well again?

I'm going to look into doing what SaveTheManuals has done and maybe order a vent.

 

I agree but the problem is once a seal is leaking you don't know if it is a faulty seal or pressure or if once a seal leaks if it is more likely to leak going forward. Unless something changes like removing the pressure or replacing the seal it will continue to leak so your questions are correct we just don't know. When you take it to a repair shop with a leaky seal the best option they have is replace the seal. You personally could continue to refill it or try to solve the problem with changing the vent some way but a repair shop isn't likely to have a customer that understands or wants to bother with it.

 

What's the P/N for the LSD vent? My diff is wet on the passenger side, again. I had axle seals done last year, but maybe just replacing the vent and making sure diff fluid is topped off will keep me from needing to do seals again.

 

It is: 23156298

 

Twelve bucks at rockauto (excluding sales tax and shipping).

 

 

Hi, I recently took my ATS with a LSD to get diagnosed at the dealership. I noticed the differential was dirty and hence leaking somewhere. The diagnose was that the differential vent is clogged, hence the reason the differential is leaking from both sides. Quoted at $1,200 for repairs. My question is couldn't I simply clean the exterior of the differential, swap the vent and see if the differential stops leaking? or should I change the differential gaskets also? Thanks

 

The seals may or may not be damaged too badly to work. I would change and refill the differential and then completely clean the area around all seals and watch it carefully for a few weeks under different operating conditions being sure to keep an eye on the fluid level. Note that seals can leak under different conditions and bad seals often leak when cold while the leak due to a clogged vent will occur when hot. Seal damage also occurs from the axle assembly pulling air (and road grime) past the seals when it cools with a clogged vent tube. If the original differential lube is still in there it will have a fair amount of metal content from original break in operation wear and if air/debris is being pulled back in past the seals then that will also wear them further.

The ATS axle seals are similar to what happens when an engine PCV system gets clogged causing blowby in the crankcase to find a new escape which is through the seals and it will carry oil with it. In many cases, the problem is resolved if the issue is caught early before seal damage is extreme but sometimes a seal is compromised right away. Replacing the vent, filling, and cleaning the axle is cheap and easy compared to $1,200 so I would do that first. Fluid for the diff is also cheap and the ATS doesn't hold much so I would drain and replace it during this process.

There is a fair amount of labor involved in changing seals but $1,200 is probably significantly more than an independent shop would charge so shop around if you are going through with seal replacement.

Rodger

 

Thanks Rodger I appreciate the feedback!

 

You are welcome! Good luck with your ATS.

Rodger

 

I ordered mine from GM and this is what the bag looks like, I still haven't swapped the vent to see if this will fit. But I'm thinking of selling the car. Albeit the car is fun and love the handling, I don't want to deal with hassles from a daily driver.

 

My factory vent (left) and brand new #23156298 (right) I bought off RockAuto. The only difference is the cap doesn't have as much room under it on the new vent, which has me thinking any pressure is escaping easier with the factory vent (or maybe this is the spring losing tension over time?). I cleaned the factory one and blew through both it and the new one, and maybe it was placebo but I feel like the factory one did not take as much effort to release the pressure. This is the 2nd time I've taken the factory vent off, considered installing the new one, and just putting the old one back on again haha.

These are both 5/8" hex for my 2014 RWD Performance 2.0T 6spd manual w/build date of 4/2014.

Again as I got the vent nearly off the diff, there was a faint pssst sound...the case either letting air out, or perhaps sucking air in?

20201025_162618 by C B, on Flickr

.

Whoa...we have the same username, like exactly. haha. But great message!