Hi I am a new old poster,have not been posting as I could not remember my
pass word combo! (parts-heimer?) I am getting grey hair,with losing lube out
of the front diff. breather tubes. Ford calls for ATF and that is what I have been
using.Every time I checked the level it was almost dry! I put the breather tube
all most straight up same thing! I went to my local Ford parts man and he sold
me a new front diff. cover kit,with the breather tube in the cover and a deflector to prevent oil loss plus a tube of anti foam agent.(185 dollars)
I am lucky,as I have a frame hoist to lift my Aerostar and work under it is,
much less of a strain! I pulled the front diff. out and opened it up.It looked good. I installed the new cover kit allowed the sealer to cure for two days and
reinstalled the diff. and relocated breather hose. Every thing seemed to be fine.
For about a month,untill I observed a puddle of lube under the diff. I was not
to eager to do it all over again,so I took my van to a local shop.They have a
neat lube rack,so I asked them to reseal my diff. and give the van a complete
lube service.After the lube work, they told me the diff. was well sealed and
full of lube. I had a short trip to take,so off I went after about 50 miles,I was
hearing whine noise on part throttle.As soon as I got home I put the van on the rack,dry as a bone. I called them up, they claim they did not have to
reseal the diff. cover,as it was well sealed and full of lube when I left,so the
problem is mine!!!!! Anyone know of a good used Dana Differential for sale?
I priced Jaws Gear & axle,about replacing the ring and pinion,was quoted
$800 + - if I brought it in!! Some days it doesn't pay to get up!!!
1991 4wd 4.0 Aerostar

 

I'm not real familiar with the front wheel drive axle, but in looking at my Chilton's manual are you sure you are loosing the fluid through the breather and not one of the three oil seals? Of course, since you have taken it to a local shop, you would think they should have noticed where the fluid was leaking when they did the lube job.

Ron

 

Rimdad;Thanks for answering my post,this diff. has always blown lube out the breather
tube! No seal leaks can be seen.It had the first breather tube.on the right side axle
cover.The lube ended up on the exhaust pipes,what a smell.The new cover kit was
supposed to cure this,as the breather ,exits near the left wheel well. I wonder about
the tube of antifoam,if it attacked the cover sealant? I was at our local pick and pull
parts yard and found a Dana 28-2 front diff. in a 1994 Aerostar. If it has the same gear
ratio,I am going to buy it($120) and try again. Tom 91 Aerostar 4wd 127,000miles

 

Tom,

Seems to me that if this differential is blowing fluid out of the breather tube and has been ever since you got it, then there must be something inside that is either pressurizing the differential or mixing air with the fluid causing it to foam out the breather tube. Like I said, I'm not real familiar with front axels, but is there any vacuum sensor or the like that could be leaking air into the differential causing it to foam up?

In checking Chilton manual, it indicates that there is a hose that connects to the vent. How long this hose is or where it goes is not mentioned, nor is it shown in the breakdown of front axel component parts (typical for these repair? manuals). But it is mentioned in both the removal and installation procedures. Could it be that this vent hose is needed to extend the length of the axel vent to avoid loss of fluid or could it attach to a check valve that prevents loss of fluid? We need someone with a front axel to check their setup and let us know where this hose connects.

Finally, I wonder if you could simply cap off this breather (vent) tube. I'll search the forum and see if I can find any further info on this and get back to you.

Ron

 

Tom,

After searching I've determined that the vent is there to release air from the differential when the fluid heats up while driving and to allow air to return as the fluid cools. Therefore, don't cap off the vent as it could cause the seals to leak or to suck in air. Also, a clogged vent hose will cause the differential to pressurize as the fluid heats up, thereby causing the seals to leak. Since you have not mentioned this vent hose and have replaced the cover with a new one (so the housing vent tube [breather] is not clogged), I'm thinking that you are loosing fluid through the vent as the fluid heats up and expands naturally. The vent hose is there to extend the length of this air passage up and away from the axel to avoid this loss of fluid and to allow for filtering of the air to keep contaminants from entering the axel through the vent tube.

I did a search on "axel vent" and did not find anything that told where the vent hose originally is routed. I did however find reference to the above info about a clogged vent hose causing the seals to leak. I also found a thread that indicated that you should not place a check valve (one way valve) in the vent hose line as it will cause the seals to suck in air as the fluid cools thus causing them to fail.

One post indicated that he was routing the front and rear vent hoses to a "T" and then to an air filter inside the cab. Why I'm not sure, his post wasn't too clear on that.

I'll continue looking at other sites to see if I can locate more info on the proper routing of this vent hose.

Ron

 

Tom,

Check out the post "97 front axel" by TN-EXPY (2/9/05) in the Expedition & Navigator forum. The sixth post (by ParisDakar) has an interesting solution as follows.

"Yes, I had the same front axle fluid leak in my 97 Expy where the fluid, bit by bit, gets pushed out of the vent tube, makes a mess, and even worse will leave your front axle with less than half the fluid in it after a while. Yes, Ford makes an updated axle tube but the cost is outrageous, and if you have to pay the dealer to do the work - God help you!

So here's what you do. Go to AP racing (web site) and look for 'Remote plastic reservoir 112009'. Buy this remote fluid reservoir. Mount it in front of the windshield washer fluid tank. There's a flat spot on the sheet metal behind the headlight where you can drill the hole for the bracket bolt. You'll have to remove the washer fluid tank. Use a stainless bolt and nut to secure the bracket and seal the hole with paint or sillicone - you don't need any MORE rust on this truck! The reservoir will sit pretty straight upright, test fit it before you drill. You'll need a couple of feet of 5/16 ID tubing and and a tube coupler. The axle vent tube ID is smaller than 5/16, so the coupler will need two different sized ends. I called Eldon James corp (easy find on the web) and got FREE samples of couplers which did the trick. Reroute the axle vent tube up over the frame and connect it to the tube from the remote reservoir.

Now the axle can push out all the gear oil it wants and it'll just drain right back in. Problem solved. I did this two years ago and it's worked great ever since. Any questions, post a reply and I'll be glad to help. Gotta fight these stupid design problems and the extremely high cost of Ford parts and service!"

Just a thought before you spend big $$$'s on a new differential that may or may not solve your problem.

Ron

 

Hi Rimdad; Thanks for your help. My problem,now is I have lost the ring and
pinion gears. They are howling like banshies! I said before, I have located,what
seems to be a fairly good front diff. from a 1994 Aerostar,at our local Pick and
Pull wreckers. If it has the same gear ratio as mine,I am in fat city,if not I
will have to find one.I will be getting pretty dirty,in the wrecking yard as they
do not allow you to bring in too many tools or a jack. I sure hope Ford did not
make too many changes, so I can use this later year diff. will have to wait and see! Thanks again!!!!!!!

 

Tom,

Sorry to hear you lost the gears. I assume this was caused from running it while low or almost out of fluid. If so, you might still want to consider adding the remote resevoir system suggested by ParisDakar once you replace the differential.

Good Luck. Let me know what happens with this next.

Ron

 

look on the driver side door jam the code will tell you the gears ratios for the front and rear.

 

if u in canada i have a front diff sitting on the floor . i thought i had a front diff gone so i went out an got a used 1 from a 94 aero . when i got to looking under there found out that the u joints had just a bit of slop. so as to say i didnt use the front diff an i paided cash for it so i cant return it .