Wheel bearings

[AlanPat]

I am very new to this and when I purchase my used 3500RL, I had a Montana dealer check the unit out. I asked them to check the axle and bearings. They told me that they checked it all out and it was ready to hit the road. So far I have not had any problems, but today I was doing a few little things before we head out on a 3000 mile trip and I decided to take a close look in the little hole where you would grease the bearings and it appeared that some black substance was present inside the hole. Is this something I should be concerned about? Thanks

[Art-n-Marge]

HUH? I hope I understand what you are describing but here's my opinion based on your description.

Do you have EZ-lube bearings on your rig? If so, there should be a rubber cap covering the hub. You must remove the cap to reveal the zerk fitting (pointy metal cap where you connect the grease gun). Sometimes these accidently fall off. If it has fallen off there would be a hole with black substance (the grease).

You don't mentioned the time difference and miles between these two events and how old your Monty is. It does happen to be the same model I have and I think they only offerred that from 2004 to 2006. I have a 2006. Do all the wheels look like that?

If you can see a hole with black substance, then you might be seeing the actual grease and the zerk fitting fell off. The zerk fitting screws on and I always check that they are on snugly because they can come loose expecially if someone connects the grease gun nozzle and unknowingly spins it and it inadvertently becomes loose. This shouldn't happen because the nozzle should be pressed on, grease applied, then the nozzle pulled straight off, but it does happen nevertheless.

If the rubber grease cover has fallen off and if the zerk fitting is off then the blackish substance could be the actual grease. If you can actually see the grease without removing anything, then something is wrong.

If this is the case you need a zerk fitting (unless it is in the wheel assembly which I doubt) and you need a new rubber cap. Not knowing how long the grease has been exposed the hub might be contaminated with dirt. You might have to consider getting to the dealer and get it checked out once again.

There are other types of no-maintenance bearing assemblies but I am not familiar with them.

For old-fashioned hubs, there is a round grease cap that fits on the end of the hub. These require some effort to pry off, however, they have been known to fall off when driving over rough roads (it happened to me once). But when the hub is exposed in this case the opening is about an inch or two across and you will definitely see the bearings and the hardware holding it together and of course you BETTER see some grease (very dark in color).

Good luck with this.

[Art-n-Marge]

I forgot to mention, if you have EZ-lube bearings and you removed the cap and the zerk is still on and you see grease there, that could be the overflow of grease when someone shot some more grease to replinish it during your last service.

Whoever does that is supposed to clean it off to keep things clean and clear. If that wasn't done, then there a good chance when you were driving around the grease was forced to the sides.

If you ever regrease your hubs yourself make sure you do the following:

1. Remove the rubber cover and push the grease gun nozzle straight in (do not rotate) to the zerk fitting until you feel it grab.
2. SLOWLY start depressing the grease gun lever to begin providing grease. The reason you MUST distribute the grease slowly is you don't want to blow out any seals when greasing your hub, especially the interior seal next to the brakes. You don't want to get grease on the brakes from applying too much pressure on your grease gun.
3. When you start seeing grease coming back at you at the hub, then stop. (it shouldn't need much)
4. Remove the grease gun nozzle by pulling straight out (do not rotate)
5. Clean off the grease overflow very well.
8. You might want to consider using the correct socket and driver to tighten the zerk fitting so it doesn't fall off.

[SlickWillie]

http://dexteraxle.com/e_z_lube_system That has a picture that will give you an understanding how the EZ-lube works. Like Art said, I think you are looking at some grease that was left on the zerk. Perhaps with the picture you can tell more what you have.

[BB_TX]

The instructions that came with my EZ-Lube axles said to pump new grease into the zerk until you could see the new grease coming out around the nozzle. That would be an indication that all the old grease had been purged out. It took far more than I would have guessed. I used Mystic JT6 EP Hi Temp (one of those recommended by Dexter). It was red in color. The old grease was a very dark grey, almost black, so it was easy to tell when the new grease started coming out. It took a half a tube before all the old grease had been pushed out and the red started coming out. Took 2 full tubes for the 4 wheels.
I continously rotated the tire as I pumped. And it took a lot of pumps before all the old grey stuff was pushed out.

[noneck]

So...I never use the Zerk...never will. I pull mine apart, clean all old grease, inspect cups/cones and repack the bearings with enough grease to fill the cone and reinstall into the cups. Use the recommended grease per the owners manual and my axle cavities remain empty. Currently, on this year's cycle also replacing the magnet on each wheel.

[ols1932]

quote:Originally posted by BB_TX

The instructions that came with my EZ-Lube axles said to pump new grease into the zerk until you could see the new grease coming out around the nozzle. That would be an indication that all the old grease had been purged out. It took far more than I would have guessed. I used Mystic JT6 EP Hi Temp (one of those recommended by Dexter). It was red in color. The old grease was a very dark grey, almost black, so it was easy to tell when the new grease started coming out. It took a half a tube before all the old grease had been pushed out and the red started coming out. Took 2 full tubes for the 4 wheels.
I continously rotated the tire as I pumped. And it took a lot of pumps before all the old grey stuff was pushed out.

I hate to say it but that's an awful lot of grease for only four wheels. I over-greased my old wheel bearings when I had the E-Z Lube ones and I only put in 2-3 pumps per wheel!

Orv

[BB_TX]

Orv - I was very surprised also. But the instructions said to pump until you saw new grease coming out. And being the new grease was red and the old was dark grey, it was obvious when it started coming out. When the inner cone would fill with old grease, I would rake it out with my finger and put it in a large plastic drinking cup. Had to do that several times per wheel. After 2 wheels, I had over half a cup full of old grey grease. If the new grease had also been dark grey, I would never have put that much in.
Had the old grey grease not been coming out, I would have been worried about it going where it was not suppose to. But there was an equal amount of old grease coming out as I was pumping new red in.
So, what can I say. It worked just like the Dexter instructions said.
The picture shown in the link above shows that there is quite a large "reservoir" between the inner and outer bearings. I guess the grease to fill both bearings plus the void between them amounts to quite a bit.

[bigmurf]

What happens when those wheels heat up and the grease expands?

[SlickWillie]

quote:Originally posted by bigmurf

What happens when those wheels heat up and the grease expands?

I doubt you get a lot of expansion, and if so, that rubber plug over the zerk is pretty weak. (Pulled a cargo trailer all over the country without losing any grease.) If the seal goes before the plug, you probably had a bad seal anyway. A good seal just won't blow out for no reason at all. I sure wouldn't get on the zerk with a pneumatic grease gun though. You might put grease in faster than it can exit.

I just don't worry about repacking the wheel bearings too often. Heck, I've drove vehicles tens of thousands of miles without repacking the bearings. Never had one to fail yet.

[Art-n-Marge]

I think the intention is that the EZ-lube was intended to make it easy to keep the bearings fully greased and not necessarily to do a grease exchange. Therefore as soon as you see the grease coming through then stop, wipe off what you see and you're done. The bearings should still be taken apart and inspected for wear periodically. I forget what my book said but there is a recommended interval.

Now you're gonna make me want to go recheck. Time to open the rig back up and get the book. I stored it behind a slide room, doh! It's usually where I can get to it, double doh!

[BB_TX]

quote:Originally posted by bigmurf

What happens when those wheels heat up and the grease expands?

You can see in the pictures here, that there is a metal end cap covering the outer bearing. There is quite a bit of area inside that end cap to catch any extra grease that may get squeezed out due to heating. It would catch a lot of grease before it ever reached the rubber outer seal.

[BB_TX]

quote:Originally posted by Art-n-Marge

I think the intention is that the EZ-lube was intended to make it easy to keep the bearings fully greased and not necessarily to do a grease exchange. Therefore as soon as you see the grease coming through then stop, wipe off what you see and you're done........

Maybe so, but the following is from my Dexter Operation Maintenance Service Manual.
(summerized)
1. Remove rubber plug.
2. Place standard grease gun on grease fitting.
3. Pump grease into the fitting. The old displaced grease will begin to flow back out of the end cap around the grease gun nozzle.
4. When the new clean grease is observed, remove the grease gun, wipe off excess, and replace grease cap.
5. Rotate hub while adding grease.

[sreigle]

I would guess that "black stuff" is either grease or maybe brake dust. Not likely something I'd worry about.