Stranded in Flagstaff

After more than a week of preparation in the baking hot summer of Phoenix, we finally hit the road today, Friday July 10 at around 1pm. We are heading north with a final destination of Glacier National Park, Montana.

The route takes us north along I-17 with a climb of about 5500 feet along the way. Robin and I are still green and we're getting used to what falls over in the cabinets as we drive, and shamboo bottles that decide to empty themselves as we ascend in altitude.

Going uphill was pretty steady with speeds dropping to 35 mph in spots, but there didn't seem to be a lack of power, just a lot of weight. We have the 470HP version of the Series-60 engine and the 6-speed B500R Allison World transmission. For the first 3/4 of our drive up the hill to Flagstaff (a total of about 140 miles), the coach performed well and downshifted/upshifted smoothly. After passing Munds Park, however, which is at about 6000 feet, I noticed the tach pegged at about 2100 rpm. A quick glance at the Allison keypad showed that it was in fourth gear. Forth was appropriate for the climb, but then it stayed in fourth, no matter what I tried. The selector was in Drive and the indicator said 6-4. Yep, stuck in fourth gear.

I had seen this before on our trip out from California when we picked up the coach. It happened in the morning as we entered the Phoenix valley. I pulled over and took a look around but saw nothing out of the ordinary. After spending some time on the phone with Steve from California Coach (my new best buddy), neither of us could really figure out what was going on. When I started up and took off again, it shifted normally and went past 4th, into 5th and finally 6th. All seemed well.

Well, today, the same thing has happened again. it was after about 1 and a half hours of heavy hill climbing that it decided that fourth was the top gear. I pulled off the road an an exit and came to a full stop. Taking off again the shifts from 1 through 4 were normal, but again, it would not go into either 5th or 6th gear. I drove the last 30 miles in fourth gear at about 50 mph with the engine at about 2000 rpm.

As we approached Flagstaff, we heard a clicking sound and I finally noticed that a red AC light was coming on beneath the OTR Air switch. The light came on, then off, several times. What does this light mean? It looks like an AC compressor symbol. I switched off the OTR and waited a while, then turned it back on. It still works. Hmmm.

Also, while driving around the town of Flagstaff I noticed a couple of other anomalies. First, whenever I brake, the battery imbalance light (yellow) comes on. It stays on for a few moments and then goes out again. I have a brand new set of engine batteries and the dash voltmeter reads 26 V. nearly all the time. Maybe it's related to engine RPM, but, the light goes out at idle, standing still.

It's Friday evening and I'm very concerned about the transmission. It was shifting poorly around Flagstaff and again, after a short rest in a parking lot, all 6 gears returned to service. There is nothing unusual on the transmission temperature gauge which reads between 180 and 230 and most of the time around 200. Another thing that I've noticed, especially when we're stuck in 4th is that the transmission retarder doesn't provide very much braking, if any.

While stopped in a parking lot at fast idle, I checked the trans fluid dipstick and it showed over-full, with a few bubbles. Later, at Steve's suggestion, I checked the level from the keypad. At first I got an OL-59 reading which, it turns out, means speed to high. So, I took the engine off of fast idle and after a few moments the display read OL-OK which is "oil level okay". There is another diagnostic code that we haven't figured out, however, and that's "d1 63 40".

Flagstaff has no bus service but they do have a couple of truck repair shops. They are puzzled regarding the Allison B500R model, but since it looks like a 4000 series they said they would have a look - on Monday. Steve and I decided that perhaps the best thing to do would be to drop the transmission pan, change the oil and filters, and see if anything changes. I can only hope at this point. The bad news is that I'm stuck in Flagstaff for two days, but the good news is that it's a good 20 to 30 degrees cooler here and the Cruise Air's work flawlessly. We're in the Black Bart campground which although not very fancy, it does have 50 Amp service and pull throughs.

So, here I sit, waiting to find out whether I'm a candidate for a new tranny, or if I might just get lucky with an oil and filter change. Let's hope that when the pan comes off on Monday that it's not terribly full of crud. If it is, I'll probably just have them put in the fresh oil, button it up, and head back down the hill to Phoenix where there is actual Allison service available. Oh yes, and the coach just turned 100,000 today.

Fred,

Our conversions are 4 serial numbers apart. I am pretty sure your ills may be tracking mine. I am far from a transmission expert, but I can tell you that my original transmission was of a series Allison built that had poor transmission clutch materials. Those materials were not durable and after a while there was excessive clutch wear on the 5-6 clutches. The dealer told me in some cases the wear is so pronounced the material which is shed gets spread througout the trannie and generally plugs things up.

I hope you are not dealing with those issues because the cheapest and easiest fix is a factory re-man.

Having said that dropping the pan and filters and changing fluid may in that case help temporarily. You really need to get to an Allison dealer because they have the ability to connect your transmission computer to Allison's factory via the internet and run a full diagnostic. When they do that you will see graphically how much wear your clutches have and can make an informed decision about your next step.

The AC light on the OTR will come on whenever the system experiences problems and on my coaches I have had it happen twice with similar issues. In the passenger side AC compartment to the top right is a white box that houses the relays (solenoids) that control power to the condenser and evaporator fans. If either fan fails to run the system light will come on. The reason I am focusing on those solenoids is because it sounds from your description like one failed to make good contact and you got the light, but after resuming the operation of the system it functioned properly. Those solenoids have been availble at NAPA stores and also at WW Grainger. They are 24 volt coils. If you can check their function to see if you can get one to fail. They are relatively cheap so you may wish to just replace them. When a problem is intermittent you are just guessing so until you have a total failure of the system that is my best guess.

To have only 26 volts seems wrong. If you have a multi-tester try checking at the batteries to see what the real voltage is. Admittedly at idle it will be a lower voltage than when you step up the RPMs, but that seems low. If your AC is functioning when you see that voltage at low idle then it might be normal due to the current draw of the OTR fans.

This is just a thought and those of you with more expertise can jump in to clarify, but I had a similar problem a couple of years ago and my problem was internal to the transmission but was related to several sensors. I had them replace all sensors since you have to drop the transmission to get to them and I haven't had any problem since. Good luck.

Hi Fred. Maybe there is a relationship between the trans retarder and the 4th gear issue. Did you shift manually into 4th gear or was it automatic? Did you try turning off the trans retarder.

Thanks for all your replies. Nothing to do now but wait for Monday Morning. We'll get a flush/oil change and pan inspection and decide from there.

FWIW I had a 97 Liberty with retarded tranny a while back, it developed a shift problem - took it to a local Allison dealer, he attached his laptop and told me that he needed to replace the speed sensor. 69 bucks and another 50 to put it on - I was a happy camper again. I later had the oil changed to Syntrend to help keep the temps down - fixed it.

Hopefully yours with turn out that well.

Fred, Last October I delivered your coach to California Coach after picking it up in VA. Had no issues until a few miles east of Oklahoma City. Was decending a moderate hill with assistance from the retarder and got an uncommanded shift to 4th which caused a slight overspeed estimated around 2200 RPM. At that point the tranny would not shift past 4th gear so I left the freeway at the next off ramp and called Prevost Action Service (PASS) 1-800-463-7738. The service adviser told me to wait for an hour and that the tranny should reset and all would be well. He also suggested I visit the nearest Allison service center and that the retarder temp sensor was probably the culprit. He was right (at that time) on both counts. I continued to Oklahoma City with the tranny shifting normally, had the sensor replaced and had no more issues. Due to the fact that the sensor was bad the Allison mechanic did not drop the transmission pan at that time. The fluid did not appear to be overheated or dirty and the computer parameters and codes were normal. Hope this history helps get you back on the road.

Additionally, occasional cycling of the battery balance light is normal and indicates that your equalizer(s) are doing their job. If for any reason you have shut off the 12v switch in the right hand engine bay or if an equalizer CB trips, the balance light will stay illuminated. Best of luck.

Fred, sorry to hear your having such a hard time with everything. At least your stuck in a place that's a whole lot cooler the PHX. Have you ever checked out the Lowell observitory? I've never been but was thinking about stopping by next time we go thru Flag. Is Black Bart the only choice to stay in Flag? Here's wishing you good luck tommorow on your service.

After reading Brian's post and going over pages of Prevost maintenance manuals it became clear that the failure to shift was intentional on the part of the Allison control unit. There are a few conditions that cause it to avoid 5th and 6th gears, and one of those is temperature exceeding 260 degrees F.

Not wanting to stay in Flagstaff until Monday, I elected instead to drive to Las Vegas where there is factory Allison service available for the B500R. The trip to Vegas was quite pleasant and shifting was normal for the entire route, including crossing the Hoover Dam. Had the cruise control set on 65 most of the time. The amount of speed this beast can pickup on a downhill stretch is astonishing and it's now clear that I need a retarder that's available all the time, that can hold the coach to 65 or less on a 6% grade. Maybe I'm dreaming...

I had to use the retarder on several occasions and each time I kept a watchful eye on the trans temp gauge, keeping it below the 230 mark at all times. After reading in the manual that there was a specific 260 degree threshold, I found it somewhat curious that the trans temp gauge had graduations at 200, 230, and 320 degrees - clearly a non-linear presentation. This means that if the needle ever passes 230 that it's entering into "logarithmic range" (just kidding), or in other words, very hot. I didn't let the needle get much past the midpoint between 200 and 230, even though there were times I really wanted more retardation. I stabbed the service brakes instead, which is recommended over riding them. The retarder really digs in when you hit the brakes, in three increments according to brake pressure, as I recall. This makes for a very rough downshift at lower speeds and when driving around town at in-town speeds, it seems better not to retard so that downshifts are smoother.

So, tomorrow I'll be pulling into W.W. Williams to find out what they can do for me. At a minimum I think I'll have them do a full diagnostic, change the oil and filters, and perhaps upgrade to synthetic oil. Depending on the results of these tests, I'll either hit the road and hopefully make it to Glacier National Park by this weekend, or, bust.

Our spirits are still high and we're growing accustomed to our new living quarters aboard the bus. It's very nice, overall. We're in the Oasis Las Vegas RV Park and it's got everything we need. Oh, and the rear CruiseAir konked out with HI PS again, two times. These things are simply not reliable when the temp is over 100.

Fred,

Sounds like you are getting pretty good at trouble shooting. Sometimes it just takes time to sit down and think it through. Do you have a Jake Brake and a transmission retarder or just the trans retarder? If you have the Jake Brake did you try using that? I have found that ging down hill the Jake Brake has done a great job. I occasionally have to manually downshift to 5th to hold my speed with an occasional stab on the foot brake. As you have discovered, the retarder really heats up the trans fluid, and that is not a good thing.

Hope you get good news at Allison.

Fred,

I have always limited my transmission temp to 230 even though I know the transmission brain is programmed to shut down the retarder if the temps reach its limit. My reasons were solely to be conservative to protect the transmission fluid whose life is compromised by higher temps.

Having said that I have learned techniques to allow driving in mountainous areas while minimiziing temperature gain, and they were used and proven in the Flagstaff area on a trip to Pahrump NV.

First, using two notches of retarder on my coach provides me with a downhill run on a 5% grade with a less than 230 degree temp and no increase in my set speed. When the grade is steeper I slow to below my 4th gear max speed of 55 and engage the retarder and fourth gear. I used that on 7% grades out of Flagstaff and the hills near Henderson NV. I never had to use the brakes and if the speed started to approach 55 I went to the third position on the retarder control. Again the temps were held to just below 230. On the steeper grades, in fourth I moved the retarder selector between the second and third positions to regulate my speed to just below the fourth gear limit of 55 (2100 RPM).

We are driving heavy vehicles and downhill runs have to be done under control at lower speeds. I was initiallly concerned about truckers being pissed because I had dropped below the speed limit until I realized they were doing the same thing. That is a western thing however, because on long steep grades in the east I notice truckers at or above the speed limit fairly common. I have stopped caring what they think of my speeds.

Using the retarder is a balancing act. If you leave it on all the time just heavy braking is going to cause your temps to spike. You have to be vigilant, avoiding heavy braking by anticipating and slowing. When you have an emergency, that is when you disregard the fluid temp spike and concentrate on braking, but by being ahead of the bus at all times you can avoid that need.

Or you can just drive the bus at car speeds, ignore the fact you have a 46,000 pound weapon, and push your fluid temps in which case your transmission fluid will wear out quickly. If you look carefully at the Allison maintenance schedule for fluid changes you will note that retarder equipped transmissions require fluid changes twice as often as those not so equipped. The reason is the heat.

BTW, the heat does not get to the transmission. The temps you see are measured at the retarder output just prior to the coolant to transmittion intercooler located on the drivers side low next to the engine.

That sounds like some great advice John. I'll try the 4th/55 combo on the next leg of our trip. Evidently, the 6th/65 combo isn't going to work :-)

I do appreciate the gravity (no pun intended) of operating a 46,000 pound monster and it's on the forefront of my mind at all times. My wife and I agreed that getting used to operating this vehicle is a bit like a new airplane of a type you've never flown before. Although you're an accomplished pilot, everything is "different". What was that sound? Is is supposed to do that? Some things are at first unsettling which later become routine and confident.

We're sitting at the shop in Vegas now, waiting to see what fortune will come our way. Our overall luck in Vegas has been mixed, but I'm hoping to break even on this round.

-fred

Fred,

At higher speeds you have more energy to absorb by the transmission fluid, so even if the transmission drops into 5th you still have the greater energy the higher speed possesses creating heat. By slowing in anticipation of a downhill grade or for traffic you are in effect avoiding that excess heat by getting rid of the speed more gradually. Leave the retarder off and see how even a small downhill grade can cause the coach to accelerate. I was a jake brake advocate, and still feel a jake has some very valuable features, but after learning to live with the retarder I find it to be more than capable and with practice easy to manage temps.

I am a fast driver in my cars, but in the bus and other large vehicles I have no choice but to drive slower because even with everything working right I still cannot stop as fast as the car ahead, I cannot make sharp turns, and generally speaking I just do not have the capability to alter speed or course anywhere near as easy as a smaller vehicle. The 62.5 mph I drive is for a reason.

Amen Jon. I'm all in on this thread. Tell us the verdict at the Allison shop Fred. GOOD LUCK!

Fred, Just a thought. Long ago, on Prevost-stuff, there was an owner of a early '90's Marathon H3-40 who was staying in Las Vegas, and he used to run a small mister under his coach keeping the pavement damp. This seemed to aid his cruise airs from hitting the HI PS in the 100 degree Vegas heat.

Our very own Jim S has misters on his Marathon Cruise Airs. He has a pressure switch on the high side and when the Cruise Air pressures reach a specific value the misters spray onto his condenser coils, dropping the pressure. A very simple and elegant set up.

I believe Steve Bennet has modified the fans in his Marathon to push more air across the condenser coils.

The point is that the key to good Cruise Air operation when on the highway is to make certain the cooling efficiency of the condenser is not compromised and if needed get more cooling across the coils. But before anyone starts to re-engineer their coaches the first step should be to pay attention to what Jack Finch has done, and that is to optimize the performance. Cruise Airs are very sensitive to the correct freon charge and if set up with the right charge their performance will be very good. If I remember on my old coach (haven't had to touch the Cruise Airs on my current one) as little as an ounce one way or another makes a big difference.

I also put two electric radiator fan in the mid center intake hole of my Mid Cruise air. Just a dash switch to a relay and on they go. I have yet to have the chance to see if they do any good. My mid A/C is my problem child, major dismantling to get to and intake and exhaust close together under the bus. I these fans help but not enough I will add misters. I believe Jim Shoen found out that the mister will not hurt the AC fan or coils.
Greg

Quote:

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Originally Posted by flloyd

Our spirits are still high and we're growing accustomed to our new living quarters aboard the bus. It's very nice, overall. We're in the Oasis Las Vegas RV Park and it's got everything we need. Oh, and the rear CruiseAir konked out with HI PS again, two times. These things are simply not reliable when the temp is over 100.

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Fred,

I have found that my cruiseairs work quite effectively while parked in temps as high as 107 degrees (the limit we have been in so far). With roof air or cruiseair, I think giving them all the help possible in super hot weather makes a big difference. Opening the awnings helps shade the sides of the coach, lowering the internal shades helps even further, and not allowing the coach to get heat soaked to start with is key. I also have the sunscreens which attach to the windshiield and door and drivers windows. Those help as does closing the internal windshield shades on really hot days. That drivers area is quite a greenhouse and can generate a lot of heat.

Seems like all the testamonies and discussions on this site about the hi temp shut down of cruiseairs has occured while running with the coach in motion over super hot pavement. In the shade of a stationary bus, not sure I have heard of anyone having the problem. I have to believe you have some problem with the unit itself.

Aside from putting down shades and snapping on outside screens, Liberty suggests raising up coach when parked on hot pavement to increases air circulation under coach for the cruise airs.

It's called the Montana solution. Tonight I'm in Dillon Montana and the outside temps are an unbelievable 58 degrees F. Robin and I couldn't be happier just to be here.

We took the bus over to W.W. Williams in Vegas and spent a good part of the day there. It was about 110 outside and it wasn't long before we lost the fore and aft cruise-airs. Anyway, we hooked up the bus to the Allison technician's laptop and took it for a test drive. Nothing unusual. The only error code it had stored was a previous over-temp incident. No active error codes. The test drive of about 20 miles in the scorching heat was uneventful. The transmission shifted normally and I even threw in a few hard retarder decelerations to see if we could get an error - nothing. We returned to the shop and the tech smelled the fluid. He said it was fine. He had no recommended service as none was indicated.

I wanted to do _something_ so I had them do a fluid and filter change with Transyn. It was expensive ($682) but I felt that it would be my best chance at peace of mind. After a few hours we hit the road and headed north along I-15. The performance with Transyn seemed a bit better and a little cooler. It's normal that when you spend several hundred dollars on a hunch that it "feels" better and yes, indeed, it did.

We spent the night at a nice, quiet off-highway rest stop in Utah and aside from the generator giving us problems, it was a nice stay. This morning, we hit the road and continued northbound and landed in Dillion, MT, at a campground from the Big Rigs book. It's very nice and much cooler than we expected. We're loving it already. The trip had a fair amount of ups and downs, and even a few stretches of interstate in Utah where the posted speed limit was 80. I kept it at 65, however, except for some very long and gently sloped downhills where I let it creep up to around 75. The Silverleaf readout was indicating a ridiculously high MPG and the road was straight and clear for as far as the eye could see, and so it was comfortable going.

During the latter part of the trip, through Idaho and into Montana, we were usually at 65 or below and had some fairly steep downhills. I think I've mastered retarder handling now and was able to keep safe speeds and low temperatures throughout the route. All is well.

Getting back to the generator, a Kohler 20KW, did give us a bit of a concern last night. It was a dry camping night and we needed the AC units. It wasn't terribly hot, perhaps in the high 70's, and so we started with all four cruise airs on. One of the first things I notice is that when the generator starts very badly. By that I mean that it shakes quite a bit and sounds like it's banging around inside its compartment. It seems to start on one cylinder, then two and after a few seconds, on all four. It seems very apprehensive and I'm certain that it should start with less effort.

Once the generator is running, however, it purrs along at the customary 1800 RPM. Purrs, that is, until the load changes. Every few minutes, when one of the cruiseair compressors kick in, the generator RPM drops significantly, and we have a major brownout. I observed a voltage low of 108 on the panel and it took the generator 4 or 5 seconds to recover. I then shut down two of the units and still the same behavior. I'm thinking that this generator isn't getting enough fuel when it needs it, and/or the governor isn't keeping up with the load properly. Whatever it is, it's a problem that I have to troubleshoot and fix. The combination of sluggish starting and poor load regulation leads me to consider fuel starvation, perhaps a restriction in the filter, clogged injectors, an injection pump problem, or a governor problem. I plan on sliding the unit out tomorrow and observing its behavior as it starts and hopefully through a brown-out episode. Maybe I'll be able to see something and get some more information.

I know from Mango Mike's blog that this unit once had a fuel pump failure and he did a nice writeup on how to substitute and automotive electric pump in its place. This was temporary and eventually the factory pump was replaced. I'm not sure if any of this is related, but it's a data point to consider.

So, as things go, I suppose this thread, now moved from "Houston we have a Problem" into the Engines, Transmissions, axles and wheels area, is once again drifting off-topic. But, what the heck, we're sorting out transmission issues, cruiseair issues, and now generator issues. I won't even mention the streaks of oil I saw today coming out of the port side drive axle hub. They seem minor by comparison.

To all, your thoughts are eagerly anticipated...

Fred, the hub oil leak should not be treated casually or taken as insignificant.

Check it out as soon as you are able!!


JIM

Fred,

If your generator has not been run under heavy loads it needs to be. Run it often, and keep increasing the loads. The fact that it starts rough suggests it might be carboned up internally and just needs to get a hard workout to clean up. If it was the fuel pump my guess is it wouldn't run with any load on it. Just guessing, but before you spend ton's of money be patient and try to work it.

As to the leaky hub seal that is a relatively easy cheap fix (maybe $50 for the seal and a couple of hours labor depending on which axle) but failure to do so will have serious consequences. Until you get it fixed make sure the differential (if on the drive axle) or the hub (if on the steer or tag) has lubricating oil. Do not overfill the front or tag hubs. The fluid level needs to be approximately 1/8" above the bottom of the clear plastic.

This is a guess, but as you exercise the bus you are likely to find other things that show up, including other leaking hub seals (don't mess with them unless they leak), leaky suspension valves (creating the leans), etc. This is normal stuff and once you get past the transition from a coach that sat idle for a while to one where it is being used regularly things will be pretty trouble free.

If you do your own work I can talk you through a hub seal replacement.

Fred, regarding hub seals I went through several in a short period of time with my first coach.

When we got that coach we were living in NY state and we ended up using the coach frequently. We traveled a lot and used it to get to trade shows so it was on the road often with zero problems. When we moved to Knoxville the use of the coach all but stopped for almost 2 years because we were finishing up our new house and settling in. When we got back to using the coach I had three hub seals start to leak in succession. I replaced them and until I sold the coach never again had an issue with the hub seals.

Our current coach was used frequently by the original owners and we have continued to use it often. I cannot tell if any were replaced prior to my purchase of the coach, but I have yet to have a single leak.

My point is our coaches are meant to be used and used often. I think we do more harm by not using them than we do by adding up the miles with frequent use.

Fred
If the Generator and engine sat for a long time the fuel filters on either could have problems. I was told recently by Dick Wright of WRICO (the generator man) that the fuel pump pumps far more fuel then the motor uses, hence the need for a return line. The other thing he told me was that you should run the fuel line return bypass flow pet cock slightly open so that any air could easily bypass the intake of the engine. He didn't call it that by that is the only way I know how to describe it.
GregM

Fred,

If you see oil on the outside of the wheel, you should take a look at the inside of the wheel with a flashlight from the opposite side of the bus, I would guess it will be very apparent. You should get that taken care of ASAP as it will only get worse in the heat we are experiencing. When you get it replaced, make certain the hub is filled with oil prior to it being put back on the axle. We have had two members with axle problems because of dry hubs being put back on the axles.

Change the fuel filter on the gen, it may be just that simple.

Good news on the hub leak. It's not the main seal. Checked the backside of both drive wheels and they're clean. Here's how it looks from the outside:

http://clicktron.com/images/IMG_2244.JPG

Had the very same thing on my 97. Passenger drive axle seemed to be leaking pulled the center cap and the leak was just on the front side it turned out to be the drive flange gasket not the seal. Very easy fix and just penneys so to speak for the gasket, hope that is all you find. Happy travels, Bill.

Some Generator fuel filters are made of folded papercartridges. As these soak ovrr time the come apart and plug every thing down stream of them.
Whatch these closly and change often or find a better built one.