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davidsisco · 10-26-2016, 07:34 PM

The last thread I could find was in 2007 concerning rear end troubles...I have a 2011 thor windsport 36f on a 2009 ford f53 22k chassis...I bought it in 11/15 with 34500 miles...Occasionally after even a short trip I could smell what seemed to be either a hot oil or hot brakes. I could never pin point the location. Monday after about a 20 mile trip home I again smelled a horrible hot odor. This time I actually climbed under the unit and checked the rear rotors and they were both too hot to touch but the calipers were ok....I then touched the rear axle housing and it was also too hot to touch..on the left inner wheel I noticed almost dry oiley residue so it looked like the axle seal has been leaking. After things cooled down I took the oil fill plug from the rear end and it had plenty of lube and didn't smell burned at all..On an old thread the location of the axle vent was mentioned to be in the wrong location letting water get into the rear end causing bearing troubles.. Since I have only driven about 1000 miles total in the last year I have no way of knowing its past life. I have no whine, and nothing to indicate bearing problems..But with the hot temps after a short run something is not right.. has anyone else had anything similar? I hope Good Sams will handle the issue.......

TeJay · 10-26-2016, 09:18 PM

Since you don't really know the history you're only option is to have the differential checked at a shop. The Ford comes from the factory with a full synthetic lube which is great. We had a 1999 and the differential (DF) did go bad with less than 10,000 miles but it was replaced by Ford.

With the synthetic lube I'm thinking that if one of the bearings is bad the others will be protected. I'm surprised that you have not heard any noises. Usually the bearings will make a definite noise. The gears (ring and Pinion) will also make a howling noise but we drove ours home from ME to MI with it howling and there was no heat.

Maybe the lube has been compromised with some water as you said you had read. Again only a good heavy duty shop can determine what is going on.

Why not get an infrared temp gauge for $20 at HF (Harbor Freight) and check some temps after a short trip. I find it strange that the rear rotors were to hot to touch. Under normal driving they will be hot but not that hot unless you were working them hard. Were the pads smoking at all?? If one of the calipers is sticking that will for sure cause excessive heat which based on what you said could also be causing the axle to be hot. The TEMP gauge will help to isolate the hottest area.

If you have to just drive it a short distance maybe 2-5 miles and check the temps. If it's a caliper sticking you'll know it at the rotor and before the axle gets hot from heat transfer.

Unless you have a bad bearing which I'd think you could perhaps hear it from inside in the rear it almost has to be sticking calipers. Keep in mind if a front caliper sticks you'll know it because the RV will pull to the sticking side. In the rear it won't effect the steering because of it's position and the weight.

I'm still thinking it something to do with a sticking caliper.

Also consider this. Without some hands on time I can't explain why the DF is getting hot as well. Except you just might have more than one thing going on at the same time which can and is confusing. Diagnose, diagnose, diagnose. Check one thing at a time and eliminate something. The heat gauge will help with the temp location. Do the short drive. If it's a sticking caliper it will heat up very quickly (probably less than a mile). If it's differential fluid that will take longer.

Do let us know what you find.

twinboat · 10-27-2016, 04:38 AM

After reading your last sentence, I think your on the right track.

Get it to a shop to check it out.

If mine, I would chock the wheels, place the shifter in neutral with the brake off and jack up one side, under the axle.

An 8 ton bottle jack, lifting it 1 inch is all you need. Then you can attemp to spin the lifted wheel. I would say, you should be able to get a half a turn of free spin, out of it, if things are OK.

You could jack each side, one at a time to compare the resistance to turning.

If it doesn't free spin at all, when you stop turning it, or you can't turn it at all, something is wrong. But we know that by the burning smell.

With out jacks, safety stands, large tools and experence, you are going to need to find a shop to pull it apart.

Do get it checked. Driving it like that can damage more $$ parts or leave you sitting, broke down, on the side of the road.

TeJay · 10-27-2016, 06:24 AM

These type of problems are the most interesting to diagnose. The symptoms are the clues and should be followed, heeded and solved one at a time.

Lifting one wheel at a time to do a free wheel spin is a very good diagnostic idea. That would perhaps isolate the problem. If one bearing is tight it will or should show.

One problem with taking the weight off a rear wheel is sometimes, but not always, with a significant amount of the rear weight off the wheel things may not react the same way. Usually any potential noises are significantly reduced with out the weight. You have not heard noises which may because of their location or there are not any.

I'm still mystified about the excess heat in more than one location. That has to be the main symptom.

twinboat · 10-27-2016, 07:51 AM

On other benefit of lifting is that you can use a bar or shovel to check for any up and down or in and out movement.

There shouldn't be any movement.

davidsisco · 10-27-2016, 10:50 PM

I talked to a ford service tech at a dealership today that I have known for years and of course they don't have a way to work on a large unit but he said the df does generate a ton of heat and being hot to the touch is normal. I climbed back under it tonight and I am kinda leaning towards his theory...With the calipers not getting hot and with a slight oiley residue on the inner left back wheel it seems the seal might be leaking slightly and dripping on the rotor causing the hot burning smell. I saw like a charcoal residue on the rotor indicating burnt oil. I checked the fluid level again and it is full enough when the plug is removed oil drips out. The plug is magnetic and there was fine residue stuck on the plug , like the etch a sketch filings, but no chunks of metal so hopefully no bearing damage. Being 68 I have been a diy'r for all my life and have tackled most everything that I felt comfortable with on cars but this large a unit spooks me...I also talked to a large truck ford dealer in Memphis and they have an opening next week so since I have the good sams policy I am going to let them tackle it. I haven't noticed any drag when driving it and again no whine or clunks so hopefully no major damage internally..I hope just amybe the seal and replacing the seal and cleaning up the rotor and brakes will get it fixed....I rell y appreciate all of your comments and clues and will post the results asap....thanks again, david