Wheels: Inspect Steer Axle Hub Oil

 Inspect Steer Axle Hub Oil 

How do you check the steer axle hub oil? Found that the only way I can do this is to almost completely pull the wheels. Have to take all the lug nuts off to remove the hub cap. Anybody make a hub cap with a removable snap off or screw off-center? 

I drilled a hole in the center of the hubcap to allow me to inspect the fluid level.  

I put a piece of tape across the hubcap going both ways to find the exact center to drill the hole. 

by Barry Beam 2003 U320 40′ 

Be sure to check the inside of your wheel.  The seal is on the inside of your hub.  If you have oil inside the wheel and on the disc brake rotor, you need to have the seal replaced (a job for the Pro’s only).  As with others, it looks, (to me) more like minor seepage by the red (hub oil fill) plug, and possibly overfill, depending on how level the coach was at the time of the picture. Your drive wheel looks like it could be just the hub gasket. 

I discovered a front wheel seal leaking while at TN RV, on the way home, last spring.  There was no evidence of seal leakage whatsoever on the outside of the wheel, but the inside of the wheel and the rotor was well doused with leaking hub oil.  The level in the hub was about half way between the full and add rings.  

Due to some bad work performance during this stop (first time I’ve ever had a poor experience at TN RV), I did not let them touch the hub assembly.  I had talked with my Cummins service center near home in NH, and based on that discussion, removed as much oil as possible from the hub and then added Lucas Hub Oil back to the full mark (a couple of times over 4 days……because the oil has to seep through the outer and inner bearings to equalize the level).  The Lucas oil is a proprietary blend of synthetics for extreme duty applications.  

Professional truck fleets use it whenever they have evidence of a seal going bad and the racing crowd uses it for its extreme service/durability rather than standard hub oil. 
I cleaned the inner part of the wheel and the disc brake as thoroughly as I could.  Then I checked the inside of the wheel frequently during the rest of the way to NH.  I never had to add any more hub oil and after the residuals were “slung out” in the first hundred miles, I ceased seeing anything inside the wheel. 

A front seal replacement is expensive and well worth finding a highly-skilled shop.  There are more ways to screw up a seal (and hub) than Carter has Liver Pills. 

BTW, my son is a trucking Owner/Operator and a very thorough Pro in all of his work. Age and heat and rough treatment can certainly prematurely fail a seal. But there is probably a far less evident underlying cause as well.  He has had steer axle seals last well over a million miles on one side and well less than a hundred thousand on the opposite side of new Peterbilt tractors.  He attributes it to assembly line issues and mechanics not being knowledgeable in their handling of the seals, bearings and hubs, improper torquing during reassembly and failing to adhere to acceptable run-out tolerances, among other things.  He won’t trust anyone else to do his, but himself. 

When I had my seal replaced  this summer, that side was not properly torqued, “as Found”.  When they checked the other side, torque and run-out were perfect (@ 146K miles).  

Neil Pillsbury 1998 U270 36′ 

Age and heat …. I’ve had to replace a couple of mine over the years, mostly on the tag for some reason. 

The hubs should use 85W gear oil or Synthetic gear oil, you can find it anywhere including Walmart. 

Just remove your front hub caps and tag axle top hats (pull off the decorative lug caps and the rest will come right off).  Once done you will see a red cap, its a rubber plug and will pull right out.   Add in the gear oil until you are at the full line and put the plug back in. 

The drive axle is a different beast, only the front axle, and tag axle will have these fill ports since in those areas all that is turning is the wheel.  The drive axle will have a shaft that goes back to the differential.  The axle, differential, etc is filled with lubricant.  So if you have a leak there, I believe you need to drain the differential, undo the hub bolts, replace the seals, refill the differential and that will not be measured in ounces of oil. Steve Cook 2003 U320 40′ 

When I bought the five-year-old coach, it had just had the front hubs serviced.  I soon found oil streaks and was told to look for it being overfilled.  That was the case, and eventually, the streaking stopped. 

Then a few months ago, two years later, I take it to an expert for service and have the hub oil changed.  Now it is streaking again.  It was pointed out to me at the rally last weekend. 

Tonight I take a look, and the oil is as full as it can get, right to the rim.  Well above the full line.  Time to take some out.