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Tag Axle Bearing Oil Overheating
I am on the side of the road on the I-76 exit ramp about 80 miles east of Denver, CO and am waiting for a mobile repair truck provided by Coach Net but I would like to know what may be going on.
While driving on HWY I-76 my Pressure Pro TPMS alarmed and showed a temperature reading on the passenger side tag of 202 deg. F. I pulled off as soon as I could and checked the tire temperature with my Flir Heat Gun and the tire temperature was fine compared to the other tires. After taking a few more readings around the tire I was getting ready to say that the sensor was bad when all of a sudden oil started to come out of the chrome cover and dripped on the tire. I should have never doubted my Pressure Pro. I popped the cover off and saw that the center plastic plug had popped off which is why the oil was now coming out. The oil temperature measured about 300 deg. F and was foaming and still expanding.
The oil now looks shot.
I can only guess that it is either a wheel bearing failure or a dragging break that has caused the problem. Anything else I should consider?
How do I determine the part number for the wheel bearing (if that is the problem) or is the part somewhat standard? I have the Prevost P/N from the Prevost parts book but that probably won’t do me any good with the local truck repair place.
Any help would be much appreciated.
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45 Replies
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Andy. You might be ok . Those caps will shrink and fall out causing you to loose some oil in there . With less oil it will get hotter. I’m no expert but if it were a bad seal I believe she will leak out the back not from the hole it thats where you saw the oil . Good luck and be safe .
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Thanks Al. I hope you’re right but I did not see any evidence of oil until after I was stopped for a few minutes which is when it seems that the plug popped off and the oil really started to come out. Even now, the only oil that is on the wheel is what has poured straight from the hub to the ground. The rest of the wheel is clean. Also, that oil seems to be shot so at the very least it would need to be replaced.
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Hi Andy,
When the service truck shows up you need to get the center cap off the hub and inspect the bearings for damage to see if they froze.
Get the wheel off the ground and try to spin the tire and listen for noise or resistance.
Changing a bearing on the side of the road is doable as long as nothing but the bearing seized.
Later
bv
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If it were a dragging brake, you would smell it. Hot brakes can be recognized easily.
Have the drum pulled and check the spindle. Hopefully it is not gouged.
You may or may not need a new bearing. Replace the seal and the oil.
Good luck
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Thank you all for the prompt responses. I’ll report back with what we find.
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One last question, how often should the hub oil be changed out? The coach has almost 134,000 miles on it and I’m not sure that the bearing oil has ever been changed on that wheel.
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Prevost book on the differential is 48 months 200.000 miles.
Alot of guys do 100.000
Later
bv
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Andy,
Any oil on the backside of the tire and wheel, look across with a flashlight if needed?
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Thanks Tom. No oil that I can see on the back side of the tire. Still waiting for the mobile repair truck so I’ll have a better look when the tire comes off.
Thanks Bernie. It sounds like I should replace the hub oil when I have the differential serviced?
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I’m curious as to the cause. I believe the brakes are Meritor disc brakes on the tag axle and the description of the problem could indicate numerous reasons.
First, was the coach recently lubricated? I ask that because the Meritor brakes when overgreased can hang up or drag. A dragging brake can generate a lot of heat.
Did the coach have a recent hub seal service or bearing service? Improperly torquing the nut can cause a bearing to run hot.
Is it safe to assume the grease was at the correct level? If it was low a bearing would not be properly lubricated, but if it was low I cannot imagine it leaking out unless the heat distorted the plastic cap and caused it to leak whatever grease was in the hub.
But regardless of the cause which must be determined and corrected before further travel a detailed inspection of the bearing and proper brake operation is imperative.
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I was wondering in a situation like that could you lift the tag and drive to a repair shop??
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I was able to drive to a repair shop and it appears that the source of the heat was the brakes as an be seen in the pictures. The wheel spins freely and no evidence that the back seal was broken.
They don’t have the parts for the brakes, does anyone know of a reputable repair facility in the general Denver area?
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At one time I believe Prevost tag lift was disabled above a certain speed. I don’t know if that is the case on this vintage coach.
I suspect there is a reason for the tag to drop, because when the axle is lifted the brakes are disabled and then it becomes a safety issue with 1/3 of the axle brakes disabled.
All this is from memory and may not be correct. Like Tom forgetting to send dues to me, I forget other stuff.
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I drove with the tag down and kept the speed low and monitoring the tire temperature while I drove and it stayed in line with the other tires.
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My preference is always a Prevost service location, but when I couldn’t make the drive to Prevost service location I have used the Stewart & Stevenson location listed below. They have a separate bus/coach shop and they are familiar with Prevost coaches. They won’t have some of the “unique to Prevost” parts on hand and will have to order them, but they do have local access to the more general parts like bearings and seals.
Stewart & Stevenson
5840 Dahlia Street
Commerce City, CO 80022
Tel:(303) 287-7441
Toll Free:(800) 727-7441Oh yea, I forgot to mention, they aren’t cheap!
I’ll check back later today to see if there is anything that I can do to help.
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