I know this issue has been brought up before, but what exactly is the fix for the issue? My passenger axle tube and everything nearby are soak with gear lube...
Rear axle vent leak-what is the solution?
- Thread starter lsp408
- Start date
I may be the one that you are refering to as having this problem before. The solution is to lower the fluid a little under the fill hole. That's how mine finally stopped leaking after having the rear end replaced because of the blown pinion seal. This cars seem to be over filled from factory, and that's why the leak thru the vent or worst yet, blow the pinion seal like mine did.
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I am actually going to change the vent cap with nipple then hook up hose to the catch can. One of my friend did that and working good.
Btw, I saw a brand new roush 5xr did the same thing. But boss 302 didn't. I didn't see any different setup between boss and roush....
Btw, I saw a brand new roush 5xr did the same thing. But boss 302 didn't. I didn't see any different setup between boss and roush....
The Boss 302 dosen't have a vent on the axle tube . The vent for the the rear end on the Boss 302 is on the top of the fin alum. rear end cover .
Because the fluid expands and contracts as it heats and cools, if the differential is over filled it can leak. This can be more pronounced during spirited driving when the differential heats up beyond normal day to day operation.
Most people that track their cars run in to this. the Shelby KR has a catch system on it to collect the expanding fluid. I believe you can still purchase these from Ford.
Most people that track their cars run in to this. the Shelby KR has a catch system on it to collect the expanding fluid. I believe you can still purchase these from Ford.
If you have lower rear end gears and/or exhaust dumps... Your axle will be operating at higher temps than normal.
Higher weight gear oil solves this... 70-140 or 75-140. After replacing the seals and gear oil, never had any issues with leaks since.
Higher weight gear oil solves this... 70-140 or 75-140. After replacing the seals and gear oil, never had any issues with leaks since.
SicShelby09
Banned
The actual solution is to install the Shelby gt500 kr vent tube. It's a few inches longer and stops the fluid from coming out. That's what the tsb for the gt500 is. I assume the kr vent tube will fit ours. Dont lower the fluid. That's just stupid.
Really, that will be cool if they have that bladder thingy vent... I was going to cancel my appointment tuesday but since you mention new psb, I may take it in and see whats up.
no wonder i did not see boss 302 leak axle fluid
The TSB is not for the 2011 GT. I tried to go that route.
Let's look at it this way. I found in the manual that the V6 model uses a lot less fluid than the regular GT. Both use the 8.8 rear end, so what is the difference? So I don't think that lowering the fluid a little bit is a bad idea after all.
People here are talking and they have not been in my shoes. I for one don't do autocrossing or spirited driving(taking turns) and the damn seal blew off in the highway! Another brand new stang off the lot went for a test drive and the same thing happened!
SO...they come overfilled from factory plain and simple. If you don't do none of the slot racing or whatever just change the rear cover to a Boss type of just lower the fluid a little. Btw, mine still wets around the vent and that's with the lowered fluid. I've been around mustangs most of my life and this is the FIRST one that I've seen that wets the axle vent like that. The vent is mostly to release pressure the gas expansion that is created inside. You should have seen it when I decided to take the vent out to see if it was defective. I heard all this built up pressure that came out and was like WTF? Also, I think that the spring in the vent cap may be too stiff and is not allowing the gases to be expelled to the atmosphere easily. I ordered a new oem vent with the part number from the 87-04 mustang and it feels softer.
At the end, do what you want since it's your vehicle. But I've been through this experience.
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This seems to be an entirely plausible explanation. It is a conclusion that I have seen many reach on the web. Yet every factory axle assembly I've ever checked (I've had three complete assemblies shipped to me from FRPP now) was dead nuts as far as fill level and this includes measuring the fluid levels in well used assemblies that never leaked.
From what I've seen, the factory rattle cap can get bound up. Instead of allowing air to move back and forth (between atmosphere and the inside of the housing) pressure builds up and forces the housing to puke fluid (from the pinion or axle seals or when great enough it overcomes the resistance at the vent and blows it out). Spirited use only exacerbates the issue.
Here's a shot of the factory "rattle" cap vent
You are correct about the TSB, however specific in application it may be. Here is the TSB bladder next to the factory vent
The "bulb" helps to contain fluid that wants to exit the assembly, allowing it to eventually drain back as well as acting as a vent. Far from optimum in terms of performance but will definitely help if you are seeking a quick fix.
Here's a snapshot of the TSB (note it lists the part number for the bulb itself as well)
That is correct. The Boss cover is identical to the SVT PP equipped GT500 unit (which has shown up on some standard units as well). Baffled internally as well as externally it is an excellent alternative to more expensive aftermarket covers.
As previously mentioned, Ford moved the vent from atop the passenger side axle tube to the top of this cover, as shown here
Available at ~$70 (Buyfordracing) it is an excellent value. Were I to pick one up I'd drill/tap the cover so that I could insert both fill and drain plugs. It is an easy mod that makes servicing the axle fluid rather simple. If you're feeling industrious, you could always pick up an Explorer/Mountaineer rear cover and modify it to fit yourself. That cover can found for even less that the GT500/Boss cover.
They were never available from Ford - only from Shelby. There was a time when anyone could purchase them direct but now Shelby has labeled them as warranty only - meaning you have to show proof of KR ownership in order to purchase one now.
Shelby GT500KR Axle Reservoir
I suspect their inventory was getting low and they have no intention of another manufacturing run, hence the "warranty only" label. They function well but their fabrication and quality control left quite a bit to be desired.
Here's a writeup I did on one so you can take a closer look at how they worked.
As depicted above, the KR "solution" was a bit more than just a longer vent tube. It was never used for any TSB (it is not a Ford part) - only the bulb I mentioned before was. The KR reservoir will fit most any '05-'11 S197 chassis. You could piece together your own (of far better quality) from simple aftermarket parts and for less money as well.
Tob
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i like the bulb thingy. I guess I may still take my car to dealer to see if they will put one of the bulb on. if not, I will just rig something close to that
Tob, thanks for the detail pictures and description.
Tob, thanks for the detail pictures and description.
You're welcome.
Of note, was the pressure my factory GT500 3.31 assembly had built up inside it. The car sat all winter long, untouched. I raised the rear of the car in preparation to install the KR tank. Since I had heard of it before I paid very close attention when I was removing the factory vent. It was very quiet in my garage and as I was turning the vent counter clockwise to remove it, I reached a point where it started to hiss (similar to pressure built up in your gas tank that you hear venting when you twist off the cap). It did this for a good five seconds.
I was surprised how tightly sealed these things can become.
Elevating the vent location and allowing the housing to breathe should cure your problem, no matter what method you so choose.
Tob
Of note, was the pressure my factory GT500 3.31 assembly had built up inside it. The car sat all winter long, untouched. I raised the rear of the car in preparation to install the KR tank. Since I had heard of it before I paid very close attention when I was removing the factory vent. It was very quiet in my garage and as I was turning the vent counter clockwise to remove it, I reached a point where it started to hiss (similar to pressure built up in your gas tank that you hear venting when you twist off the cap). It did this for a good five seconds.
I was surprised how tightly sealed these things can become.
Elevating the vent location and allowing the housing to breathe should cure your problem, no matter what method you so choose.
Tob
Thought I'd share my experience with the TSB balloon catch vent with you guys. Ordered t from one of the preferred Ford dealers and promptly installed. On my 2012, the vent is on the drivers side of the axle tube, which confused me since every reference thread I've seen said it should be on the passenger side. Any way, it went on easy but it hasn't seemed to stop oil from puking out of the axle tube vent after hard driving or canyon runs. Found quite a few drops of oil under my car over the weekend and proceeded to wipe down my muffler and a couple of pipes/tubes that were covered with he diff fluid, which by the way smells awesome (not really).
So the TSB part hasn't solved my issues but I have no doubt the diff would have spit out more fluid without that balloon catch. Sucks that the Shelby part is no longer sold to the general public and that there aren't any bolt on aftermarket parts out there to fix this issue.
So the TSB part hasn't solved my issues but I have no doubt the diff would have spit out more fluid without that balloon catch. Sucks that the Shelby part is no longer sold to the general public and that there aren't any bolt on aftermarket parts out there to fix this issue.
I put a Trickflow cover on my rear with main cap supports. It has a drain and fill on the front cover which is just the right amount of fluid that the rear takes. That fixed my little residue problem and makes gear oil changes easier at the same time. Plus it aids in cooling a little better.
I ordered bulb thingy and will put it on as soon as I get it. If that don't work. I'll just buy boss rear cover with vent
Boss diff cover sounds like a good option, but what happens to the axle vent? Do you then have 2 vents or do you plug the axle vent?
I also saw the thread where Tob fabricated his own rear diff cover using a stock cover off the new Explorer. Friggin awesome, I would never have the skills to do that.
I also saw the thread where Tob fabricated his own rear diff cover using a stock cover off the new Explorer. Friggin awesome, I would never have the skills to do that.
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Corruptor - I've seen photos of the relocated vent (on 2012 models) as well as the vent still being located on the passenger side (early 2012 production maybe?). Either way, if I was you I would start by verifying that the fluid elevation within your factory housing/cover is indeed correct. If it was overfilled, when you remove the plug at the front of the "pumpkin" it'll leak out (at level ride height). Start there. If the fluid is at the proper elevation then check to see if your rattle cap is loose - as it should be. Not the threaded portion which extends into the axle tube but instead the crimped tin cap that resides atop of the short vertical tube.
If it doesn't jiggle a little then your housing may be building up pressure and then forcing fluid past the vent. The solution has to be somewhere within the above. Beyond that, a move to the factory SVT PP/Boss cover would definitely be a good move. Better cooling potential via the fins, easier drain/fill capability if you get it drilled/tapped on the bosses for plugs, and the relocated vent is a good idea as well.
If you'd rather have the catch can, there are plenty of nice billet cans that you could use with a simple bracket, hose, and replacing the factory vent with a simple barbed fitting (which gives you a spot to clamp the hose to). I'd definitely like to see what you end up doing and how well it works for you.
Good luck.
Tob
If it doesn't jiggle a little then your housing may be building up pressure and then forcing fluid past the vent. The solution has to be somewhere within the above. Beyond that, a move to the factory SVT PP/Boss cover would definitely be a good move. Better cooling potential via the fins, easier drain/fill capability if you get it drilled/tapped on the bosses for plugs, and the relocated vent is a good idea as well.
If you'd rather have the catch can, there are plenty of nice billet cans that you could use with a simple bracket, hose, and replacing the factory vent with a simple barbed fitting (which gives you a spot to clamp the hose to). I'd definitely like to see what you end up doing and how well it works for you.
Good luck.
Tob
Thanks Tob! I'll check the rear diff level per your suggestions. The good news is I did check the rattle cap on the stock vent cap before replacing it with the balloon/TSB part and it seemed to move up and down fine.
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