Tag axles oil check

[Gene Obie]

Pardon another seemingly stupid question. But what is the procedure for checking tag axle oil level? I see references here that the entire chrome hub assembly is held on by the lug nuts? To just check the oil level does the outer cap unscrew or pop off or do I need to remove that entire chrome hub? Tried to pry the "outer cap" it a bit but didn't see it move much and don't want to mess something up. Does the Roadmaster center logo need to come out first?

[Gene Obie]

BTW, for every stupid question I ask I get about 100 answered through previous posts or other resources on this forum. So thanks to all who contribute to this forum it been such a great resource for me.

[Mike Shumack]

Gene, that chrome cover and cap looks like the same on my Coach (from what I can see of it). You can pop off the center cap and leave the rest of the chrome cover in place. Just stick a screw driver or such in the gap and pry the cover off. When reinstalling you will need a rubber mallet.

[Gene Obie]

Thanks Mike. After further inspection i found a slot in the cover that happened to be out of view. It popped off easy and fluids looked good. I hadn't realized the tag hub was wet lubricated and should be checked often until reading the manual the other night. Got lucky on that one - lesson for me I need to keep scrubbing the manual for routine maintenance items.

The oil looked pretty dark and will need to be changed soon (new to me coach didn't come with much in the way of maintenance records). Looks like I need to pull the hub bolt covers and remove the entire chrome hub cover to get the drain plug out. I see amazon sells a plastic coated lug nut cover removal plyers that looks like it will come in handy. Hoping I don't have to actually remove any of the torqued lugs to get the cover off - need more tools for that.

[Mike Shumack]

Note, that just draining the oil using the drain plug in the hub cap, you are still not draining all the oil out of the bearing "sump" (the cavity between the wheel bearings). So you are only draining some of the old oil using the drain plug (which is better than nothing). Then you fill with new oil and let that mix with the old oil still in the hub as you drive. Then you can drain the oil again from the hub drain plug, and you will have removed most of the old oil which is now mixed with the new oil. This is a good as you can get without removing the wheel assembly and bearings to drain.

Also remember that just replacing the oil is not the end of the maintenance task. You should be inspecting the bearings every so often depending on how much you drive (maybe every 150K miles or 5 years - or when you put new brake linings on that axle), so at some point you should remove the wheels and pull the bearings for inspection. Or if there is any signs of metal (glitter) in the old oil, then you need to pull the bearings and inspect/replace right away.

[Keith Moffett]

Went to Source Engineering in Venetta Or.  One issue they fixed was the front wheel bearings which I had over filled.  Aparently they have to be filled very slowly to just below the lip.  When filled properly I noticed a temp drop on the TPMS where the driver front had reached 30 degrees higher that all the rest.
Food for thought!

[Mike Shumack]

Glad you got her fixed.
When refilling the hub, you need to add oil slowly to the hub so the oil can seep through the outer bearing and fill the sump. Then you let it sit and settle out to check the level. If you overfill you should be able to drain a little out through the drain plug (just put the drain at around 3 o'clock to slow/control the amount that comes out) or use a suction gun. Too much oil can result in a leaking wheel seal because there is not enough space for the oil/air to expand into as the oil heats up. Too little oil - well you know what happens.

I think it is unlikely the overfill caused your tire temperature to increase by 30 degrees. I believe what ever was going on with that tire was just a coincidence. It would have to get "very hot" for the heat to transfer from the wheel bearings all the way through the wheel to the tire. Maybe you had a dragging brake caliper.  IMO.

The important take off, is that the oil needs to be in good condition and at the correct level. Now you can check that task off of your "to do" list.
Safe travels.