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YZF571 · 08-13-2014, 01:26 PM

So, I am going to be servicing my rear differential this coming weekend, the research I have conducted steers me to a 75W40 lube. While looking for it I find that this now seems to be refered to as 75W140. It lists the specifications as WSL-M2C192-A for both the 75W40 (out of the owners manuel) and as the same on the 75W140 on Motorcraft's web site. On the same web site there is a foot note proclaiming "Note: For a complete drain and refill, some limited-slip axles require addition of Friction Modifier, Part Number XL-3. Refer to Workshop Manual or Owner’s Guide"
Does anyone know if a 1996 F-53 with a 460 V-8, E4OD, Dana 80 w/ 5:13 gear ratio would require that additive, also can anyone confirm that 75W40 at some point became 75W140.
Also while I'm at it.......this entire project is brought on by a hot gear oil smell that seems to be coming from the passenger side rear wheel area after long trips in hot weather, it does not seem as prevailent on the drivers side. The vehicle has just over 20,000 miles on it.

subford · 08-13-2014, 03:13 PM

I have never heard of a 75W40 or any oil that has the lower number last.
I think it was a miss-print in the manual.

The copy of the 1996 F53 owners manual I have says full synthetic 75W140 oil.
Page #167. Manual attached.
There should be a tag on the rear end telling you what to put in it, mine did.
As I recall mine called for full synthetic 75W140 oil.

jamesrxx951 · 08-13-2014, 03:21 PM

Quote:

Originally Posted by subford

I have never heard of a 75W40 or any oil that has the lower number last.
I think it was a miss-print in the manual.
There should be a tag on the rear end telling you what to put in it, mine did.
As I recall mine called for full synthetic 75W140 oil.

Agreed, I to believe that is a misprint as the 40 should be before the 75. 75W140 has been used in these heavy DANA (and Ford) axles for a while. No friction modifier should be needed. I have not seen a motorhome spec axle with a limited slip axle. The easiest way to check is to get both rear tires off the ground and transmission in park. If one wheel spins pretty easy while the other spins the opposite direction, you have an open differential and no modifier is needed.

DieselTech39 · 08-13-2014, 03:40 PM

I agree with the previous posters that it's probably a typo in the manual; and, the test for the limited slip differential. Just a note on the hot oil smell on the right wheel....could be a wheel seal is starting to leak, may want to check that.

House Husband · 08-14-2014, 01:03 PM

The hot oil smell is probably coming from a leaky hub seal. Look for oil on the inside of inner wheel. It's possible that the RR brake is dragging, creating enough heat for seal failure.

Richard

YZF571 · 08-14-2014, 02:15 PM

Thanks to all that advised, much appreciated, I will get to the bottom of this this weekend, I hope!

Capt. Flipper · 08-17-2014, 06:12 PM

HInt:
Before you go changing fluid or replacing parts, check the level of lube in rear axle. With vehicle level, it should be 3/4" below fill plug. Put too much in and it will blow out the axle seals, usually on the passenger (low) side and cause smell when on hot brake rotors. Had this exact problem on a 99 F53 chassis when lube was up to the fill plug level. Could save yourself lots of work.

jamesrxx951 · 08-17-2014, 07:09 PM

Quote:

Originally Posted by Capt. Flipper

HInt:
Before you go changing fluid or replacing parts, check the level of lube in rear axle. With vehicle level, it should be 3/4" below fill plug. Put too much in and it will blow out the axle seals, usually on the passenger (low) side and cause smell when on hot brake rotors. Had this exact problem on a 99 F53 chassis when lube was up to the fill plug level. Could save yourself lots of work.

If that's the case the vent would be the likely cause of that. The vent is supposed to be open to the atmosphere so no pressure should be created in the diff housing to cause a seal leak. An overfilled diff can cause the fluid to purge out of the vent but never seen it cause a seal leak or cannot think of any reason it could cause a seal leak.

The axle seals on these large DANA rear differentials are so robust a slightly overfilled diff would not cause them to leak. It would have to be a lot of pressure. And most likely the pinion seal would leak first. The seal on your rig just wore out or was damaged at another point and started leaking.

YZF571 · 08-18-2014, 01:10 PM

Well I got into that rear end over the weekend and here is what I found. The oil level was right up where it should have been, that is to say I could touch it with my pinky finger at about a quarter inch down from level with the drain plug. But I'll tell you, that 20000 miles on the coach must have been pretty hard on that rear diff for whatever reason. That oil was really stinky, (didn't smell burned, just stinky, awful smelling stuff!) it was also really dirty compared to the stuff I topped it off with, or at least a completely different color. In the near future I will drop the inspection plate, remove the wheels, and service everything under there, lube the brake pins just in case there is a hangup there? Maybe the fact that it is nearly 20 years old? @ Capt Flipper, wish I would have know about the tad bit low stuff earlier, I wouldn't have added any. Also of note I did take it out to the track over the weekend, only a couple hundred miles but it was just over 100 degrees and I drove between 65 and 70, burnt gear oil smell on the passenger side. Thanks once again gents, appreciate all of the input.

YZF571 · 08-18-2014, 01:25 PM

What does everything look like? Is it all dark, black or burned looking? Was the gear oil evil smelling? If so, that's low lube or heat from towing. I have had a rear axle temp gauge on my towing rig for some time now and it isn't hard to reach 250 degrees. It's a cmbo of high loads and high speed that makes heat. Also, the lower the gear ratio, the hotter the axle will run (more teeth and friction surfaces to generate heat). I have found that at 55 with a given load, the temp is 180. I increase to 70... it goes up to 225.

It would probably be worth putting in a temp gauge, at least. Autometer makes a nice one and they also sell a bung you can weld into the steel cover, or you can buy an aftermarket voer that has a built-in port (I use the Mag Hytec)

Just happened across this post in a Ford forum, thoughts? ..........

The Dana 80 had a so-so reputation in towing circles... at least in the extreme end of it). It's used as a medium duty axle, but it isn't really one. It has a high torque rating but a relatively low oil capacity and tend to get hot.That's one reason why Ford started putting the finned covers on them. They die like flies in motor homes due to cooked oil. The aforementioned temp gauge and an expanded capacity cover will help a lot. If nothing else go to 15K oil changes

jamesrxx951 · 08-18-2014, 03:11 PM

Quote:

Originally Posted by YZF571

The Dana 80 had a so-so reputation in towing circles... at least in the extreme end of it). It's used as a medium duty axle, but it isn't really one. It has a high torque rating but a relatively low oil capacity and tend to get hot.That's one reason why Ford started putting the finned covers on them. They die like flies in motor homes due to cooked oil. The aforementioned temp gauge and an expanded capacity cover will help a lot. If nothing else go to 15K oil changes

It would be important to note that the DANA 80 is only used in the F350 dually and some year F450 Superduties and maybe some light duty chassis cabs to the best of my knowledge. The only Motorhomes im aware that they are in is the 16K and 18K chassis.

Arch Hoagland · 08-18-2014, 04:25 PM

I carry an IR gun and my rear end is always around 155 to 165 degrees.

Have you ever shot yours with an IR gun? You could trace heat on the axles with it also.

NeilV · 08-19-2014, 03:30 AM

1996 with 20,000 miles and hot lube smell on passenger side would be time to check the brakes on the curb side of the vehicle. When was the last time that they were flushes and the caliper guides touched with silicone grease? You may have a brake issue that is heating up the axle and cooking the lube.

YZF571 · 08-19-2014, 07:31 AM

Yeah NeilV, that is the plan. I am almost certain that there has never been a service or a check for that matter. Arch, I am thinking it is time to pick up an IR gun, looks like they can be had for a decent price and could be pretty benificial in the trouble shooting department. Hopefully between the changing out the lube, checking the brakes, I can get all of this behind me and lose that awful smell. Thanks folks for the thoughts, don't have much experience with things such as this and am rying to learn and save at the same time.