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Topping off hub oil levels
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I have been very aware of my hub oil, I use an air power vacum pump and very small hose to suck out the old oil. I do this on average once a year. By doing this over time my oil looks like new everytime I suck it out. I refill to the top line and install new plugs, yes it’s a little over kill but no problems, no oil being pushed out the breather hole and best of all in about 100,000 miles between 2 buses no wheel seal leaks.
I know, I just may have cost myself a wheel seal failure by saying this!!
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Kevin, If you ever figure the way to prevent wheel hub seal failures let us know. Over the years on each bus including the current one I have had one or two failures. So out of 6, on average 4 never leak. Of the ones I replaced, they never leaked after replacement. The two coaches I sold each approached 250,000 miles when I sold them so hub seals can last a long time or for reasons I cannot figure out they can fail anytime. My current coach had two fail immediately prior to my taking possession of the coach and were replaced, and one of them was leaking within months and had to be replaced. 80,000 miles. Go figure.
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Ok, you guys were right. The inner hub seal on the tag axle is leaking badly after I refilled the hub. I’m not really set up to change that in our driveway so I’ll have to find a shop. Do I need to order the seal from Prevost or are these common seals that I can get from Napa? Should I have them change the bearings at the same time? Pretty sure the bearings were run with low fluid for some time.
Thanks, Gerald
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The bearings and the bearing race are very easy to inspect, and unless there is evidence of being run dry such as surface imperfections or discoloration your bearings are likely OK.
The hub seal can be sourced locally since they are generic, but there is no reason to not buy them from Prevost. Orfer a seal for the cap also.
The front and tag axle seals are relatively easy to change and the only caution I would offer is to either pre-lube the bearings or take great pains to fill the hub to the proper level. I think you disc brake calipers if they are the Rockwell type will swing out of the way so you can pull the hub. The Knorr-Bremse use one time bolts that need 450 ft/ lbs of torque to replace so if you have that type make sure the shop has the bolts, also likely available from Prevost.
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I use Lucas syn oil in steer and tag I think it’s 75w 90
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I had the seal changed today at a local company that is part of the Volvo/Prevost service network. They did a nice job. Brake pads and bearings were fine. Not something I could have done in our driveway.
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I take it that the drive is different. I had my drive tires replaced yesterday and took a picture of the hub while there. Does not look anythying like the pictures posted.
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Yes, drive axle is lubed by differential oil. As part of your annual service you should make sure differential oil level reaches fill plug when bus is level.
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As part of a pre-trip inspection I would urge all owners to be vigilant regarding hub seal leaks.
We talk about them on forums but to reiterate they are double bad news. If the leak is serious it is possible for bearings to lack needed lubrication and that can have very expensive consequences. But even if the bearings continue to have adequate lube, hub seal leaks tend to ruin your brakes, coating them with gear oil so they are no longer effective.
The first clue about a hub seal leak is going to be fine lines of black streaks radiating outward from under the hub caps. On steer and tag wheels if you suspect the hub is leaking, poke your finger through one of the holes and rub it around the wheel. If the hub seal is leaking you are going to have a black greasy finger tip. If there is no leak you will just have black, dry dust on your finger tip.
The hub seal leak on the drive axle is less easily checked. Sometimes it will show up on the outer wheel as streaks, but when that happens the seal usually has been leaking a long time. The leak will show up on the inside of the inside drive wheel. The way I have found to see evidence of a leak is to shine a flashlight under the coach and look at the inner drive wheel on the opposite side of the coach. The tire and wheel are going to have lines or streaks of grease radiating outward. Also look between the wheels for evidence of grease. Both areas should be dry. It is kind of a pain to get down on your knees with your head almost on the ground to look at the inside of the drive wheels, but as stated above hub seal leaks cannot be ignored.
You may go hundreds of thousands of miles without ever experiencing a hub seal leak or you may have one on a relatively low mileage coach. I have never figured out why there is such inconsistency relating to hub seals. But if you do get a leak it is a relatively simple repair that takes about 2 hours. And the oil that has gotten in the drum or on the disc and on the pads or shoes is easily cleaned off if the leak is caught early.
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Good advise… In lubing mine this week I found a tag seal starting to leak. You really have to look close, it was not dripping, but your finger would come away with an oil slick and not just black dust. You would never catch it this early unless you’re under the bus and up close and personal.
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