New problem (possibly)

[Blacksheep]

Drove the bus today to Salt Springs, about 2 1/2 hour trip and when I parked I noticed on my H3 the small 18 inch or so high bay that is directly above the drive axle was really hot including its contents! Could this heat be generated by the rear drive components? This bay is nowhere near any heat source. It (the floor of the bay was so hot that even leaving the bay doors open for 3 hours, they're still warm to the touch. What caught my attention was when I grabbed my awning rod from that bay it was almost too hot to hold!
I just never realized this in the past and it has me wondering!
Keep in mind that this is a small in height (approx 18-20 inches) bay that goes from one side to the other.
Any ideas or is this just heat from the rear?
Ace

[Zeroclearance]

Ace,  many folks have stuffed there battery bank in this void over the drive and tag axle.  Do you have the skirts or the storage bins?

On my '03  I just have the large skirts.   The only thing that is this area is our air tanks and air compressor dryer.    Yes, we have our drive axle diff.    Do you smell gear lube venting>>is it hot?   How is the sight glass for your tag gear lug level.   I assume that your disk brakes are fine?   

Are you venting your genset into that area?   A lazer sight heat gun is valuable for checking things.   BTW, my dark charcoal paint on my skirts measures 167 degrees on a sunny day.

[Blacksheep]

I guess this a storage bin. I thought I made that clear but maybe not!
I smell no odor of any kind such as gear lube. Nothing but heat and I don't smell that, just feel it! No venting of anything in this area. I just keep 4 of the plastic under bed type storage containers with odds and ends and that's it! My marine on board battery charger is in this area but unplugged and off while driving!

Ace

[Lin]

Ace,
     As you know, heat/energy does not come from nowhere.  As was mentioned, an IR gun would be very useful.  You may have drive until it heats up again and use the gun to trace the migration.  Just a wild guess, but it would seem that the floor of the bay should not have enough mass to hold the heat for a long time.  It could just be dissipating heat from something heavier. 

[Tom Y]

Ace, 140 degrees is the temp uncomforable to the touch. Did you feel your axles after this? Good Luck Tom Y

[Blacksheep]

Yes as soon as I noticed there was an over abundance of heat I felt the drive axle hubs and although hot not more than expected to the touch.
The floor of the bay which is not the floor of the bus was hot to the touch as was the surrounding SS frame members. The floor is very thick plywood covered with very thick vinyl all factory!
I looked again today and can't see anything in the bay that would cause any heat. Only way for heat to enter would almost have to come from below!

Any other ideas?

Thanks...
Ace

By the way, this place is not perfect but is it ever nice!! I was also given a list of lots here that are privately owned that will rent them out for ten bucks a night! What a deal for future visits!

Ace

[compedgemarine]

Just a thought but is anything different about the bus, i.e. to you now have a trailer you didnt pull before, the mud flap underneath is damaged or missing now? wondering is something is affecting the air flow under the bus in that area and now the air is stagnating and getting hotter rather than flowing out from under the bus. just a thought.
steve

[Lin]

You aren't parked over your barbaque grill are you?

[Hartley]

Brake heat soaks into the driveline and any massive metal areas and slowly cools after use. Tire heat also soaks and without air flow takes a long time to cool down.

I don't think that you have a problem but could be wrong. The IR gun should help you locate problem areas. It is probably due to limited cooling airflow caused by turbulance in the driveline/transmission area.

I know the heat boils out of the wheelwells on my MC9 for a couple of hours after shutdown and the back wall of the rear bay is pretty warm mainly due to the wet tank being up against the wall forward of the drive axle.

Dave...

If you look for a given problem long enough One will be created to satisfy your curiosity...... Hmmmm....

[akbusguy2000]

Ace: the only thing I can think of not previously mentioned is coolant or hot fluids.  If your heater lines, steering hydraulics or transmission fluids pass over the compartment, or through it, this may be the source.   I don't personally see how that much heat could "migrate" from the brakes or axle housing - especially with all the air movement under the coach while under way. 

tg 

[Blacksheep]

Ok this is kind of reaching but what we "think" caused the excessive heat is when I parked I immediately dumped the air in my tag axle and then the air in the front end to level/lower the bus. When this happens the bus sits pretty low. Low enough in fact that is right on the tires. Tires being hot could transmit heat thru the floor which is not insulated along with normal heat from rear drive etc. and also the bus being really low to the ground at this point that no air can circulate thru or under.
I DID say it was reaching!
I talked to service rep from prevost and offered that it could be that OR a dragging brake which I think I would have felt, but didn't or a low tire pressure which isn't! It could have been doing this all along and I just never noticed it but will check it out more when I get home tommorow. Before I dump the air I will check for excessive heat to see if there is a difference!

Ace

[Sojourner]

After stand still for an hour or so will allow heat from tires, differential, transmission, alternator and engine to soak up by whatever over it. Heat goes up. My MCI get hot and put in about 12000 miles before rebuild project. It normal....you IR gun to see for your self.

FWIW

Sojourn for Christ, Gerald

[Lin]

It is just amazing how many of us can have these machines, begin to think we are getting to understand them, and then they come up with some sort of surprise.  I do not see how I could hope to keep such a thing without a resource like this board.

[edroelle]

"OR a dragging brake which I think I would have felt"

Ace,

Your coach has plenty of power such that you may not feel a dragging brake.  I did not fully release the brakes on my MCI 8 one time, and I did not feel a drag - and I had only about 280 HP.

Also, there are coaches that burn due to dragging brakes starting a tire on fire.  Since the driver is unaware in these situations (or they would have stopped), dragging brakes may not be evident.

With DD3s on my MCI8, I would need to release the park brake, press hard on the service brake, and let the bus roll with very light throttle to confirm there was no drag.  I would try to remember to do this every time - unless I forgot.

The key was to let the bus roll, to assure the brakes were not dragging.

Ed Roelle
Flint, MI

[NewbeeMC9]

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96451

I think this is better than the HF one I bought a couple of years ago for the same price, but quite handy for detecting bearing and tire failures before they get carried away.  This one goes to 968⁰ F.  I usually plan a stop (for me and my bladder) about half way on my trips and immediately check tire and bearing temps before they've had a chance to cool.   I have noticed the sunny side tires are a little warmer(duh! ), but i use it all over., you can even check for hotspots on exhaust etc.

I vote standard issue tool for busnuts,  add to tool box list!

Yeah Lin,   I wouldn't be able to have a bus without this board.  Or at least I'd still be staring at in the driveway