Normal or trouble brewing?

[Ck2hans]

The TPMS shows my inside passenger dual wheel is running 20 deg hotter than the rest of the wheels and the PSI is running 1-2 PSI higher than the rest.
Is this normal or is there trouble brewing?
Chuck

[Fratto]

We leave from Taos headed to Amarillo tomorrow. I will pay more attention to the temperatures. On the drive axles, I would think that if it was an oil issue it would show up on both sides. If it was a bearing issue, I would think that some of the heat would migrate to the outer dual. I know that the outer dual probably has more airflow / cooling but surely it would not be the same temp as the drivers side when the inside dual is warmer? I would think that a dragging brake or other issue would create much more than a 20 degree delta.

Is your TPMS internal or screwed onto the stem? If the latter, can you swap sensors and see if there is a calibration issue?

Has this 20 degree delta been constant, did it just show up?

[Ck2hans]

Mark:

Good input, the TPMS are external. I will swap the sensors to see what happens. Might crawl under the coach (with jack stands) when I get home and back off the brake adjuster a tad to see if that makes a difference.

Chuck

[Ck2hans]

UPDATE
Swapped the TPMS on the passenger duals (inside to outside and Vice versa). The temp still shows 18-20 deg higher on the inside (which is now reading as the outside) and still 2–3 PSI more. Sooooo I am guessing the brakes are starting to drag on that wheel. Will attempt to adjust it the next time I get under the coach.
Chuck

[PrevostNewbie]

Chuck, i think you have auto slack adjusters.

[Ck2hans]

Mike:
You are correct, when I think about it about 6 years ago I had a similar issue and believe it was the same axle. I backed off the auto adjuster a few clicks and that fixed the problem. Going to get under the coach and back off the adjuster a couple of clicks again and see if I can get another 6 years out of it.

[Fratto]

Good Morning ... back in the Texas heat. Here are my tire temperature observations from Taos to Amarillo and Amarillo to DFW.

Coming down the canyon from Taos to Espanola using the trans retarder and some brake: Front tires normally in the low 120 range or in the high teens. Drives in the high 90's to the low 100's depending on sun exposure. Tags in the 130 range. However when stopped at the various stop lights in Espanola after the the descent, the drivers tag went to 150 and the passenger to the 140's. 30 to 45 minutes later with highway driving temps were back in the 130's. Could be that the drivers side has the muffler, radiator, trans cooler (with retarder running in the 230 range) etc. contributing to heat?

From Amarillo to DFW: Front and drives same as before. Tag on the drivers side mid 130's and passenger high 120's. Although it takes and hour to two to get to these temps. However as we get into the DFW stop and go traffic, the tag temps both went into the 140's sitting at lights. At this time, we also were running the generator and you guessed it, the exhaust pipe also runs past the drivers tag. While checking into the RV park and idling the drivers tag goes to 150 and the passenger to 140's.

I wish I had paid more attention to the temps rather than just the pressures in the past. Now I am not sure if this has always been the case or if it is something new. Anyway, with highway air flow, tags can in the 130's but when stopped the temperatures climb.

Chuck: On the drives, mine were always the same temp +/- 2 degrees or occasionally 4 degrees different.

I have Prevost Nashville researching the caliper issues and if I learn anything I will let you know. We will likely stop by there on the way to or from Busapalooza in Petosky in September.

[PrevostNewbie]

Mike:
You are correct, when I think about it about 6 years ago I had a similar issue and believe it was the same axle. I backed off the auto adjuster a few clicks and that fixed the problem. Going to get under the coach and back off the adjuster a couple of clicks again and see if I can get another 6 years out of it.

I have manual slack adjusters on my bus, i am curious as to how you can back off a few clicks and not have them go right back as soon as you apply the brakes.

[Fratto]

Good Point :-)

[Ck2hans]

Mike:
Don't have a good answer for you, just know it worked the last time. Will see if I am lucky twice.
Chuck

[PrevostNewbie]

That's not how auto slack adjusters work, you might have a bad one.

[Ck2hans]

Mark:
Other than the passengers side dual my temps on all the wheels are similar to yours. Interesting how the tags run hotter than the rest.

[Fratto]

Thanks Chuck ... Its good to know.

[Coloradobus]

Have you checked your caliper piston boots for integrity and piston lubrication. If a piston is sticking, adjusting slack adjuster wont help. My 2 cents. Im assuming like our former 2000 Marathon H, you have disc all way around

[Ck2hans]

Jim:
I do have disc all around. Calipers were rebuilt about 2 yrs ago with new pads, coach is kept in a climate controlled garage so rust/rot of caliper pin/boots is unlikely although I do have that on the radar and will be checking it out. Biggest obstacle at this time is finding time to do it. Don’t have any trips planned anytime soon so it’s on the get around to it list right now.
Thanks for the thoughts/input

[Ck2hans]

UPDATE:

Pulled drive axle duals off on the passengers side after driving aprox 50 miles to get them up to temp. Visual inspection showed no signs of dragging, released the parking brake and was able to turn the axle by hand without any effort indicated no dragging.
Just drove from Fl to Al on hot sunny day, TPMS Showed average temps of 115 tp 120 BUT passenger inside was indicating 132. When shooting the tires with a thermal temp gun ALL tires were reading between 118-122 deg. IAs noted previously I have swapped the TPMS monitor’s around to see if one was out of calibration, but no matter what sensor I installed on the passengers inside dual they alll showed a higher temp on that tire.
Not sure what to make of this, I will continue to closely monitor this with the thermal temp gun

[Fratto]

Interesting. I have no idea what might cause that. Anxious to hear if others might solve the puzzle.

BTW, my drivers side converter rear mud flap was failing so I ordered one from Prevost. I forgot that the Prevost flap on the drivers side is very short ... just comes to the bottom of the muffler. The converter flap was within an inch of the ground with a heavy weight on it as well. It seems odd that Prevost would design, stock, and sell a short flap for the drivers side and a long one for the passenger side without a very good reason. I am wondering about air flow in that area. So I installed the Prevost short flap and will see if that lowers that tag tire temperature closer to the passenger side. Also, the Prevost passenger side flap while longer than the drivers side is also shorter than the converter flap and has no holes for a weight. Installed one of these too. Leave for Michigan on Tuesday and will monitor temps. Although the ambient temps will be cooler ... stay tuned

[Ck2hans]

Mark:

Interesting you mention flaps and air flow. I noticed while under the bus there is a big vertical rubber piece that's near the front of the Transmisson that has been cut to half its height and there are slots and tabs to hold a horizonal pan under the Transmisson that is not there. Starting to wonder if that's affecting air flow enough to cause my issues.
On another air flow issue, I have the Centermatic balancers on my coach and it is a large metal disk that fits between the inner and outer duals. Considering the inner dual is a steel rim I wonder if the balancing disc is holding the heat in more on the inner wheel. Question is why not the same on the driver's side?

Chuck

[Fratto]

Good Morning

OK, I have driven from DFW to Nashville and while the ambient temps are somewhat lower, the tag tires definitely run cooler with the shorter unweighted Prevost flaps. Before the tags were in the 130 range after a couple of hours. Now they are in the 118 to low 120 range. After 2+ hours, short stops will still raise temps to the high 120's. A longer stop at end of day with engine on high idle will still raise temps to 140s. At this point, I am assuming that the engine bay is heat soaked at the end of the day and the tag tires pick up this heat with out air flow from the moving coach.

I have asked around here in Nashville and no one really knows what temperature the tires (or brakes) normally run. I did run across a gentleman with a 2017 H and he monitors the tire temps using the Prevost system built into his dash. He says that his tires including the steers routinely run in the 140's while driving ... only one data point, but good to know.

Also, had Nashville check out the tag brake caliper. Learned a couple of things. 1) Somewhere in the late 90's (I think) Prevost started to change from Rockwall to Bendix brakes. They have seen coaches with different brakes on each axle! In this case, at least on the tags, I have Rockwall. 2) Rockwall brakes do not like grease. If there is too much, the mechanism will move in to apply the brakes fine but will hang on release. Someone put way to much grease in mine so they took out as much as they could. Said that I should be fine now. Heading on to Michigan in the AM and we will continue to monitor.

[RichardE]

Mark,

Bus Grease Monkey has done a handful of videos on those Rockwell/Meritor brakes on Prevosts. Might be worth watching.

[Fratto]

Perfect, thanks, Richard

[Ck2hans]

NEW INFO:

Have no idea whether this information has any relevance or not but here goes.

Was driving North in Iowa the other day with outside temps in the 50s, winds were strong and hitting the coach at the front driver's side (about 10 o'clock position). Inside passenger dual drive wheel temp was very close to the other tire temps on the TPMS for the first time on this trip. I am beginning to wonder if the higher temp on my inside passenger dual drive wheel is an air flow issue. The strong cool winds hitting the coach at the 10 o'clock position and exiting on the 4 o'clock position seems to indicate air flow could be an issue in causing the higher temps on the inside passenger's drive axle.

Chuck

[Fratto]

I am also still putting importance on air flow. Driving into Ohio in the 60's, tire temps were significantly lower and even the tags took hours to get in to the low 90's. Then when parked the tags only went to the low 100's. And that was with higher engine temperatures since we were not running dash air which engages the high speed fan clutch most of the time.