Got home today and smelled the "oil burning" smell. Blue smoke, didn't smell like brake pads. The smoke was evident from the right rear wheel. Put her in the garage and pulled the wheel. By the time this was done there was no smoke and no fluid anywhere, but there may not have been when it was smoking either. The drum was hot, the axle housing was not hot until closer to the drum/disc/wheel. The differential was slightly warm. Vent was not plugged. No obvious accumulation of lube or fluid on the inside of the wheel. Plenty of disc pad left. The actuator for the emergency brake that sticks out the back of the brake/plate assembly was super hot.

If I decide to pull the hub/rotor to inspect the brake shoes am I getting in far enough to commit to doing a full hub/bearing/seal inspect replacement? I'm getting old enough to pay a shop for this stuff and save my back, but if it's a no-brainer repair to get new seals I'd like to do it and save some bucks. Might as well do both sides right?

I'll be driving cross-country in June with a slide-in camper and want it done rather than a band aid job. It's never been checked before. 2006 F350 -- 150k miles. I'll keep searching the forum for answers but would like some opinions...

 

It's a rotor with a drum-in-hat parking brake.

Since it was one wheel it was confined only to that wheel and not an issue with the frame to axle brake hose, ABS, or master cylinder. So it could be either a disc brake assembly issue, or a parking brake issue.

Typically when the parking brake is the issue the shoe holding pins have pulled through a rusty backing plate, so everything comes off and the parking brake components get replaced. A lot of work and not cheap, as though anything here is.

If you have a disc brake issue, it can be a number of things. If I'm trying to diagnose and have the opportunity, I prefer first when this is happening to open the bleeder screw and see if fluid comes out pressurized. If it does, it's the brake hose delaminating internally. A relative cheap fix if the pads, caliper and rotor were not compromised. Note, the wheel is not removed yet.

If not pressurized, I back off the two caliper mounting bolts and check if the slide pins inward can be moved. Still the wheel is retained in place. With the bolts backed off 1/4" you can move the inboard mounted pins back and forth to see if they are free. If not, I've got a slide pin problem that needs to be remedied.

If the slides are OK, then I will either have a brake pad that is stuck in the bracket, or a caliper piston issue. Now I'll pull the wheel and inspect the foundation brake.

The caliper pistons have to be pushed in so the pistons will clear the little nubs on many brake pads. They stand proud by about 1/8" and without enough clearance will damage good Pistons if they are not the issue. When the caliper is removed it should never be hung by the brake hose as that is the main cause of delaminating hoses. If someone has a history of hose failure, they typically have hung the calipers by the hose. When pushing back the pistons with a C-Clamp or other tool, one can often tell if there is piston hang up.

With the caliper off the pads and brackets, it's easy to inspect the caliper boots for burning from the excessive temps. And if so, a new caliper is in order. Next you need to check how easy the pads move in the bracket, as they should move freely. Sometimes they rust in place, and the looser spec on manufacturing aftermarket pad steelbacks usually is a good cause here. But never the less, both the pads and rotor needs to be inspected for heat damage.

Sometimes you never find a problem, and in that cause you can assume it was either a temporary hangup of a pad in the bracket or piston in the caliper. Often it's best practice to just change the caliper. And if the calipers were not replaced in a fair amount of time, both calipers on the rear should be changed.

If the pads show any heat damage, or uneven wear, then they too should be replaced in pairs.

Often a shop does not go through the individual inspections and may miss a point, but will replace a good amount of hardware. If the problem was the hose, then the new parts are a risk for a repeat thermal adventure.

 

So you don't think this is an issue with the axle or bearings? Because of the heat involved it points to the brakes? Looks like I'll be pulling this bugger apart.

 

I'm a brake guy. Everything looks like a brake problem.

But it does sound like a brake issue.

 

Thanks Jack. I just finished surfing 20 or so videos of parking brake repairs to rear hubs. I think I'm going to tackle this. Especially since the exterior spring looks like it is super-compressed and is probably frozen.

Thanks a lot for the detailed analysis procedure. As hot as it was I'm afraid to look at the calipers! Probably going to do some replacement if the cost is not exorbitant. Are third party parts okay for this or should I spend big money for Ford stuff? Any specific parts to avoid substituting with generic?

 

I didn't realize there were that many vids out there. Guess I never need to do one.

I would not presume it's a parking brake issue based on the spring. The parking brake system works on by balanced tension, the spring at the backing plate pushes the cable out and the in-cab pedal assembly pulls the cable out. This is how modern parking brakes keep adjustment of the cabling, no more nut on a balance arm adjustment.

Since we're discussing parking brake, not that it is the issue, to release tension on the cable assembly you need two vice grips. Adjust both to grab the inner cable diameter when it exits the sheath under the cab. With one clamp onto the inner cable just behind the bracket and pull it out towards the rear of the truck, extending it out by rotating the takeup reel against its tension spring. Once extended, use the second vice grip to clamp the cable at the bracket, preventing its returning. With a loose cable, you can work on the parking brake shoes. Again, only if there is a parking brake issue.

And if there is a parking brake issue, you'll be pulling the axles and hubs, so you'll need the special 4 tang socket to remove the hub retaining nut. And a torque wrench to tighten the nut per the Ford specs.

So go through the steps first to find the problem as a foundation brake would be less work.

BTW, how often do you use the parking brake.

 

In the interest of keeping the one or two people who may be actually reading this thread because they made a click-happy mistake, I am updating the findings to amuse myself. Here is what I have found.



The above photo shows the hub and brake assy after I had sprayed the brakes down with some brake cleaner. Everything was caked with gear oil. It didn't smell like brake fluid and I don't see any leakage from the cylinder or lines. The hub was wet all the way into the inside of the rig.








If you noticed, the inside of the rotor had oil all over where the shoes didn't rub. The shoes were caked with the oil and it cooked into them. I guess they are toast. The rest of the brake assembly appears to be in decent shape. Even the back dust plate looks reusable. So now I take off the axle cover and pull the axle and hub to check seals. Having a garage is great! I can work at this on my own time without any concern for weather.

Any more advice for me so far? I'm afraid I didn't check the caliper except to slide the pins and they are free and lubricated. The piston boots don't appear to be harmed and other rubber parts are not stiff or cracked. The wheel turned easily when the tire was off so the disc brakes were not frozen or tight. I did not pop the bleed screw but still can if necessary.

Oh, check out how much oil has caked the back of the brake dust plate. I believe that's the last pic. Hard to tell what order they downloaded.

 

I forgot to say that I still suspect something somewhere is making the brakes hot. Could it be the oil inside the rotor/drum? Perhaps when I replace the shoes and clean the brake assembly more I'll find an answer. Would normal wheel and axle temps make leaking oil smoke like that? I guess I still need to diagnose the disc brake caliper and see if they are a part of the problem. But they weren't tight at all.... Maybe my bearings are shot? I'll probably replace them if they aren't too expensive. I hate dealing with new races though.

 

Guess I should have not discounted your "smells like oil" comment.

The smoke point of lubricating oil is in the 200C range, close to 400F. That's higher then the average guy running around light.

I would just go through everything step by step.

 

Have taken my time fixing this rear end brake thing. I thought that I would post an update. Found the following;
1) Parking brake shoes were oil soaked and the disc pads looked as if they were cooked. Maybe they sometimes have a red appearance, but I've never seen it before.

2) The dust shields were beginning to rust completely through. It was a matter of weeks before the shoe retaining pins would have pulled through. One of them was already doing it.



3) The replacement parts were expensive, even though they were aftermarket.
4) The axle spindle was beginning to rust into the rear seal. They are a pain to clean up. Wire brush, emery cloth and some fresh primer and paint fixed it.



5) The seals are big and my seal removal tool was barely up to the task. Harbor freight stuff bends. Tapping the part of the seal that bonded to the spindle expanded it so that it would come off. Without expanding the metal I'd still be there messing with it.
6) Installing new seals stinks when they are larger than your driver set. They must be driven in with the hub on a hard surface. I used a wooden block.
7) The emergency brake cable was a pain until I pulled it out and put vice grips on it to hold it out. Then it was a matter of getting the collar out of the slot on the bracket. Thanks toomanytoys!
8) The disc brake caliper bracket is a bear to remove. The two bolts were put on by the Incredible Hulk. I had to use a long pipe on my breaker bar to budge them. My torque wrench doesn't go up that high for installation either! 200+ ft/lbs is insane. I just put the impact on after I torqued them to 150 and blasted away for a few seconds. BTW, blue thread locker on almost everything.

Here's a pic of the new brake assembly on the workbench. I hate the Dorman shields but that's all there was available.



Here's the passenger side, ready to have the brakes bled and the pumpkin juice replaced. I'm going to suck out some and put in fresh. Gotta get some limited-slip additive first. Gotta love the clean look before it gets driven. Maybe it will be a while before I have to do more maintenance? I sure hope so.

 

Red pads are an indication of overheating then rust. Or rust from a vehicle that has sat too long.

Yep, ain't a little truck so you need big truck tools. One of out test drivers, a big strong man, tore a biceps muscle removing torque bracket bolts, and they were never on a vehicle for more then a few weeks. Put in place that removal always had to be done with an impact, going on we always had a very long torque wrench to get to torque.

That's the way we expanded a stuck inner seal sleeve too.

Glad you got it together.