Massive gook buildup on brake drum

[muddog16]

Brian, there are 4 grease fittings around the wheel, housing for the S-cam has one, slack adjuster is two, and where your brake shoes pivot on the housing allowing your brakes to rotate is 3 and 4, one each for top and bottom brake shoe. My WAG is the same as Luke's!  Good luck!   Pat

[Buffalo SpaceShip]

No, I appreciate that, Larry. I was just looking at the pics and what I observed and seeing if there was another explaination.

So, assuming it's a wheel seal, which # part do you guys think failed in the pic below?

[Stan]

Brian: Now that we know what kind of hub assembly you have I will try and help you further.

Consider the two possible sources of the grease/oil. It may be from an external source and if it is  my guess would be a worn S cam bushing having too much grease pumped into it. If it is from an internal source that takes a more detailed explanation.

Think of your hub assembly being like the front wheel and a damaged inner seal (#16 & #17) will leak grease out of the inner wheel bearing (#18)  into the brake drum. The reason the seal is leaking may just be old age or it might be a bad inner bearing causing excessive slack and or heat.

Now look at the location of the outside seal (#1 & #3). Even though  the oil level in the differential is below the axle tube, going around corners and parking on side hills will get differntial oil into the axle tube. The outer seal (note that it is called an oil seal) prevents this oil from getting into the grease packed bearing. If this seal is leaking from old age or bad bearing oil will go through the outer bearing (washing out the grease) and into the inside bearing. The inside seal is a grease seal (not an oil seal) and it will likely leak the mixture of differential oil and grease into the brake drum.
HTH

[Runcutter]

Slight disclaimer before I leave for the airport - that illustration is from my 4107 manual, when I went over to help on Friday.  Brian's coach is a 4108, and ten years newer - I'd suggest that someone who knows more than I confirm that the illustration applies to both vehicles. 

Gone for the rest of the day, Arthur Gaudet. 

[Paso One]

Hi Brian
Larryh says it pretty coarse but he is correct ( I believe)  I've only got 34 years but what I see is a axle seal leaking.  All the other pre rabble was basically trying to identify what type of fluid was leaking  Gear oil or grease.  Not wether it was leaking but what was leaking.

I go back to TOMC 's post  very early on in  the thread  smelling it identified what type of seal grease seal or axle lubed gear oil seal leaking.  Bryces soulution for getting cleaned up and home is what I would still suggest.

Then after you take it apart you can put us all in our place with the correct answer. 

[roadrunnertex]

PD4107 / P8M4108 Figure for rear hub and oil seals.
The photo is the same in the P8M4905A/P8M4108 GMC coach maintenance manual X-7564.
The number at the lower right corner TP-9142-1 is the same as the PD-4107 M/M.
jlv

[Buffalo SpaceShip]

That's a great explaination, Stan. Thanks much. I'm hoping once I do pull the axles that it will be apparent what is happening there with seals and such.

Seeing how I have a more pressing need to get the bus started, I'm focusing on that part now (new starter). At the very minimum, though, before hitting the road I will back off the slack and clean the drum as best I can, and re-adjust them all. I've been driving on three brakes for a long time, looks like... through downtown cities and country dales. The biggest concern with driving another 800 miles is the wheel bearing having reduced lube, if that's what has happened.

I'll certainly have the luxury of doing the job right once I get home vs. here... where I'm scrambling for parts and scratching my head w/o the manual. I really need to get back home and deal with the growing pile of things that awaits me there... the very least is getting back to work, and trying to sell a home to generate some income to pay for a bevy of bus repairs.

I sure don't want my haste to have a deleterious effect on my coach's health, however. Or leave us stranded someplace. I guess I've said that before... 

The most stunning news of all: With this current crop of bus-realted woes (front-end wear, rear brake gook, starter, oily air compressor, etc.), my wife is currently questioning whether bussing should be in our family's future.  Ack!

bb

[Dallas]

Brian,

Since you have one seal that has failed, you would probably well served to replace all of the seals.

The failure could have been due to heat, age, or a rough spot on the axle housing.

I would also consider replacing the ones on the other side while you are at it.

I've seen trailer axles catch fire coming down Snowqualmie because of leaking seals. And DOT has no patience whatsoever if they find you with a smoking axle, whether you are a private coach or a commercial vehicle.

good luck.

Dallas

[gus]

Brian,

More than one poster has suggested smelling the oil and it is a very good suggestion. That stuff smell awful. Chassis grease isn't even close.

A seal can fail withoug anything else failing.

I wouldn't replace all seals just because one failed. Just as an example, the others may have been all replaced recently and this one may be an original!!

Diff oil will wash out the wheel bearing grease, then the bearing will fail.

I have five antique GMC heavy trucks plus the 4104, none of them use diff oil for wheel bearing lube.

[Buffalo SpaceShip]

I finally got most of the electrical gremlins shot down and the bus is starting again. Whew!

Tonight I went out and cleaned the drum with another can of brake cleaner. Most of the surface grease is gone now, but more will probably appear on the road. An incident tonight made me certain that it's best to get going home... before I indeed kill myself here.

I was going to make a separate thread about yet another incident of my own stupidity... but will put it here instead. No need to make myself the poster boy here this week. I got trapped under the bus tonight. Yup. All of the dozen or so times I've typed, "don't crawl under the bus without blocking it up..." yadda, yadda. Nope, didn't do it. I pulled the bus off the ramps to adjust the brakes, chocked the wheels and left the parking brakes un-set so I could adjust the rears. It was really windy out, and the leveling valves started reacting, letting air out... the next thing I know, it's coming down on me. God! I didn't have time to get out from under the baggage bay without getting crushed, and even tried rearward toward the engine, but couldn't risk it... so I slithered into the "hole" between the diff and the rears.

I calmly called my mother on my cellphone... who was in the house probably 40 feet away. I walked her through setting the parking brake (pffft!) and had her turn on the master switch and fire up the DD. Boy, it was loud under there! The whole time she's like, "are you sure you're OK?!" "Fine, Mom. Just a little cozy in here." In no time the bus was coming back up and I crawled out to safety, shaking a bit.

Mom did great under pressure. I scraped my face a bit in the slithering, but no big deal. My psyche and thoughts of "what-if?" are something else altogether! Sometime in the daylight tomorrow I should test it out and see if it would indeed go all the way to where it would crush me under the bay. Sobering thought.

I even had steel quash blocks right above me in the bay I could have put beween the bumper and the axle. I could have jacked it up, or blocked it... nope, nope, nope. Dumb, dumb, dumb.

Yet another cautionary tale... I'm full of 'em this week
Brian "the not dead yet" Brown

[gumpy]

Well, I guess there's no sense in wasting board space in scolding you. Seems you probably have learned the lesson the hard way. Fortunately you were able to find a safe place.

But this isn't going to help your argument with the wife unit regarding your bussing future. 

I don't understand why it came down, though. If there was air in the system, and the levelers were working, they should have keep it up, even if the wind was blowing it side to side. That's what they do! Keep it at a constant level above the axle. The only way it can come down is if it runs out of air.

[Paso One]

WoW Brian  It's a good thing God is your apprentice  Can you imagine if it was a the day before when the bus wouldn't start.   Good thing you had your cell with you under the bus.  I'm sure your Kids could also pull off what your mom did but Good for her. Take care  ( and thats not just a greeting anymore.)  Paul

[ChuckMC9]

DUUUDE!

Ya know on each of these posts there's a "Report to Moderator" link. Should we add a link for "Suicide Prevention Hotline?"

I've thought many times about the value of a cellphone out there but rarely have it on my person when I'm working. Maybe I should get one of those geeky holsters. Well, very grateful you are still a live and well busnut. I'd wait maaany months before telling the wife, especially with the already-shaky bus relationship! I'm not sure I would have even posted it. You're gonna catch some grief for this one!

[Buffalo SpaceShip]

I don't understand why it came down, though. If there was air in the system, and the levelers were working, they should have keep it up, even if the wind was blowing it side to side. That's what they do! Keep it at a constant level above the axle. The only way it can come down is if it runs out of air.

That's what I don't understand, either. I did hear some air escaping while I was under there... and that's probably why I spent too long under there. I was trying to determine where I heard the air, but my folks live a block from the Interstate and a few miles from the airport, and with the wind, it was impossible to find it from my ears alone.

It wasn't the tank nor the chambers, since I put my ear to each of those, but could be an inversion valve or the lines to it, which were too high over my head to get my ear to. It wasn't a whole bunch of air loss, certainly not enough to pop off the parking brake. But I sure don't lose air very fast when the brakes are set.  It takes several hours to get under 90psi... which points again to the inversion valve, I guess.

I'm trying to remember when the suspension begins airing up on a typical startup when it's sat for a long time... sometime around 85psi or so... so it must have dropped below that. But it took no time for the DD to air it back up so I could be free again.

In a typical setting, my bus stays up for well over a week... that's why I was indeed surprised when it began to come down.     I guess I should figure this out today. At least release the brakes and check leakage... from above the bus!

Live (hopefully) and learn.
bb

[Buffalo SpaceShip]

I'd wait maaany months before telling the wife, especially with the already-shaky bus relationship! I'm not sure I would have even posted it. You're gonna catch some grief for this one! And I believe in full disclosure, especially here where we can all learn. I've long since lost whatever pride I was born with.

Chuck-ster! Oh, I should catch some grief for that... no doubt. No one was surprised as much as I was.

Sad truth is, that was Bus Life #2 (do I get nine??).  First one was used up when I didn't  have a cellphone, and was working alone out in the storage lot to resurrect Blue Velvet (previous 4106, for those that don't know). I was replacing the only working airbag on the front axle. When I released the fitting and she started come down, a jack slipped in the gravel and she was coming down fast!

That time, just like last night, I was happy to be relatively spry and skinny. Of course, a larger man would probably work smarter under a bus. Or never go under there in the first place.

The cellphone is now my number one piece of safety gear. A "spotter" would be even better. But very few of my friends enjoy this obsession I have with old, heavy machinery.

bb