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Help with front leaking hub
My passenger side front hub is leaking. From what I could search and find here this seems to be a fairly straight forward DIY, but I am a bit intimidated nonetheless. I drop engines/transmissions in cars, replace clutches, flywheels, etc., but being fairly new to working on the coach, I am timid…
What of these bolts removes the seal? Is it the three bolts I’ve circled in the attached pic? Do I drain the hub oil first before removing (seems logical, turkey baster at the ready)?
As you can see in the pic, the fluid level looks good, despite the leak.
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8 Replies
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Those bolts hold the ring for your hubcaps. Once you remove the hubcap ring, you will find (2?) additional bolts that secure the hub seal. Not very much oil in there, but better if you remove oil first. I had trouble at first finding the hub seal, but I found most trailer shops have them.
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Charlie,
Verify the leak you see is coming from the hub seal and not the hub cap or its seal.
If you verify the hub seal is leaking you have to remove the wheel, take off the hub cap shown and expose the nut (maybe 2 1/2″, can’t remember exact size) and that will be how to remove the hub from the spindle on the front axle.
I think you will have to remove the caliper and brake disc but if you have the Meritor/Rockell brakes that should be no issue.
Then remove the nut, slide the hub off, remove the bearings and pry the old hub seal out. The new hub seal should be installed carefully because you need the inner hub seal to rotate freely within the part that is press fit in the hub. I use a 2 X 6 and tap lightly on it as it sits on top of the seal to press the seal in place on the hub. Inspect the bearing races and make sure they and the bearings are in perfect shape.
When you install the hub back in place you must tighten the nut to the exact specs for your particular model and model year. Go to the Prevost Car web site, pull up the service manual for your coach and in it you will find the tightening requirements.
Some express a torque value and some define runout so I am not going to tell you which applies to your coach.
When you refill the hub with oil be patient. As you fill it, it takes time to flow past the outer bearing. Before driving make sure the bearings are running in oil and if you wish to insure they will not run dry initially use a bearing grease on the bearings, but with steer and tags I don’t usually do that because I know they are in the oil bath.
When you slide the hub onto the spindle make absolutely certain it is not at an angle. If you apply any sideways or up and down leverage on the seal it can be damaged.
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This is awesome, thank you, Jon.
If it is the hub cap seal, is that straightforward?
If hub seal: my next timid question, what’s the best way to jack up and then support the coach to remove the wheel? Again, I do these things in my sleep on cars, but the weight/size/dimension of the coach intimidates me.
In reading here prior to posting this thread, I was probably confusing “hub seal” and “hub cap seal”. Sounds like two different things…?
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make sure center of plug is open stick paper clip in it to clear it out it is a pressure release
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The hub seal is on the inner part of the hub and the inner portion rides on the spindle and sits stationary, the outer portion is press fit into the hub and rotates with the hub. That is what I have called a hub seal.
The hub cap seal is just a gasket that sits behind the hub cap you showed in the photo. Usually once the gasket is installed and the cap tightened, if there are no leaks it usually does not leak until or unless it is disturbed. The cap comes off with six screws and unless the gasket has been bonded to the cap or hub it comes off as a loose part. If not you have to scrape the mating surfaces with a scraper or razor blade. Obviously regardless of which part is being replaced you have to drain the hub. You can drain it by loosening the cap and catching it in a pan, but if the leak is just the cap you will not have to remove the wheel and catching it is not as easy as with the wheel removed.
After draining there is still going to be a bunch of oil in the low portion of the hub so if it is the inner seal being replaced plan on tipping the hub before it is completely removed to drain what is left.
Is the rear of the wheel soaked with a black grease? If so it is likely to be the inner hub seal and not the gasket.
The previous comment about the pin hole refers to a needle sized hold in the red center plug. That hole needs to be open to let the hub breathe as the oil heats up and expands and then cools down. If it is blocked the inner part of the hub can get some pressure in it.
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Charlie,
Is there any oil on the back side of the wheel?
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If you have Meritor brakes? here’s a couple of links you might find useful
Here’s a link with pics on another forum that I use to contribute to where I set bearing end play etc
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