Transmission and heating problems

[hlfdzn]

We’re on our way back to Alaska and have had a new problem arise along with some old ones resurface. The big issue right now is our transmission is having problems shifting up to the next gear. It hangs in gear and will not automatically shift up without me goosing the gas pedal. As it hits about 1500 RPMs it stops and if you give it more gas, it starts to vibrate/shimmy but still doesn’t shift. It’s especially noticeable in the higher gears specifically at 40-45 mph but does happen in the lower gears once in a while also. Once we’re at speed it stays fine at 55 unless we encounter hilly terrain or have to slow down for any reason. I’ve not been able to find any information on this problem specifically on the web yet but am still searching.

I’m going to give Newell a call tomorrow to see if they have any ideas but am hoping someone out might have some suggestions today. I’m also wondering if anyone has recommendations for a local Allison dealer. We’re at my brothers in MN about an hour north of MSP.

The other issues right now are that the front dash heater isn’t putting out much heat at all and the front furnace under the couch is only working sporadically.

I’m not sure if my heater core is bad or not. When the coach is sitting still, there is hot air coming out, but as soon as we get up to speed, it cools down quickly.

We have cycled the furnace numerous times and it has kicked on once, fortunately last night before stopping for the night, but this morning as we got up, it was blowing cold air. I haven’t been able to get it going again. The rear furnace is working fine so I know the propane is working.

Looking forward to your input. Thank you.

[Richard and Rhonda]

Paul,

When is the last time the filters were changed on the tranny?

[fulltiming]

Heater problems sound exactly like I have experienced on my coach. That transmission problem I have not encountered.

On the transmission, I would first check the air shift valve on the side of the transmission. If it starts leaking your transmission will not shift properly. Also check the air pressure going to the transmission. It is the top pressure gauge and adjusted in the engine compartment, front wall, passengers side. The others will be system pressure and the adjustable tag axle pressure on the bottom. These are adjusted by lifting up on the cap and rotating it to increase or decrease the pressure. When you have it where you want it, push the cap back down so it will lock in place. Newell says that the top pressure (transmission) should be set at 60 psi. I agree that mine shifts more smoothly at 60 psi but I have to run mine at about 80 psi or my cruise control doesn't work properly (something that neither Newell nor Allison can explain since my cruise control runs off the DDEC). It might make sense on an earlier coach that used an air throttle rather than an electronic throttle. When I bought my coach, the Detroit/Allison service center said my transmission air valve was leaking and replaced it. I believe it is on the passenger side of the transmission and should have an air line running to it. May or may not be your problem but certainly something to check.

I have the same issue with my front furnace under the couch. I have held off on replacing it until the weather warms up enough that having the propane shut off to the rear furnace is not a problem. In your case, the fastest (and most expensive) option would be to replace the furnace with a new one. If I were on the way to Alaska, that is what I would do. It is likely the control board BUT it could be several other things, igniter, sail switch, gas valve, etc. I would feel much better heading to a cold location where service centers are few and far between with a furnace that I could depend on rather than 'hoping' that the problem was properly diagnosed and repaired.

Last, but no least, the dash heater. First question, how is your air flow at speed? If it is pretty lousy, first make sure that there is NOTHING blocking the return air grille under the passengers seat. 100% of the air coming out of the defrosters and the dash vents comes through that air grille into the heat exchanger. If the flow of air is adequate and the heat just isn't there, make sure that the supplemental water pump located on the driver's side of the engine compartment is operating when the temperature lever on the dash is moved to hot. It is a LONG run from the engine to the heat exchanger located in the passenger's side front compartment. Without the supplemental pump, there is even less water flow through that long line. At speed, the front of the heat exchanger is getting hit from that cold air coming under the front of the coach also. I have thought about constructing a air dam from the front cap back to the heat exchanger to block off some of that air but have not determined the feasibility of that option yet.

If you haven't, you might verify that all three blower motors are working. They are located in the passenger side front compartment ahead of the generator fan. Remove the four or so screws in the metal surround after you raise the access door, slide the side panel to the rear and remove it, then slide the rear insulation/backing panel straight out toward you. You will find three blower motors at the top of the compartment and the heat exchanger below the motors. The two motors closest are the dash/defrost blower motors, the third blower motor, located further back into the compartment, is for the arm vents. Make sure that they are all working on all three speeds.

I find that my dash heater/air vents blow somewhat better when the panel is off indicating a restriction in the air flow from the return grille.

Does your engine run at about 180-185 degrees in cold weather? If not, your engine thermostat may be defective. That would also reduce the amount of hot water that would reach the heat exchanger. You might also try to blow the dust out of the heat exchanger with pressurized air, don't get carried away and bend the fins on the exchanger.


If Newell owners of 1990 through early 1994 models have a large air flow out of their dash heater/air conditioner, I would like to know. I would also be interested to hear if any early 90's owners that have a dash heater that really heats well at speed.

[Richard and Rhonda]

Mike,

On your last question about other 90 vintage coaches and warm dash air. My air is reasonably warm, but the air flow is pitiful.

[hlfdzn]

The saga continues...

Looks like I've also got some leaks on the inside upper part of the finned area on the radiator. Have any of you ever needed to have the rad's repaired? I imagine I'll need to have it pulled. It does need some repairs and a radiator repair is much cheaper than an engine rebuild.

Mike, thanks for all your information. I've check the gauges and they are normal. Hope to pull the coach to an area where I can crawl under it tomorrow to check the tranny location. One other thing about the tranny is that the dash gauge hasn't budged above 120 yet. Could be a bad gauge/sending unit though.

I'm wondering if the lack of heat up front may be related to the radiator leaking? It's a possibility...The VMSpc hasn't shown any increase in engine temp but haven't confirmed how much antifreeze has been lost.

Richard, we had the fluids all changed last year at Newell. The tranny fluid is bright red with no discoloration nor smell.

More to follow tomorrow...

[fulltiming]

You have either a bad gauge or a bad sending unit on the transmission temperature. Although Newell transmission run pretty cool, you should be seeing temperatures in the 150-160 range after the transmission warms up. You will rarely see the transmission temperature exceed 180 unless you are tied up in rush hour traffic or pulling long steep grades.

If you pull the radiator for repair have them rod it out at the same time. Crud builds up inside the radiator and restricts water flow and heat transfer. That will be a good chance to clean off the intercooler at the same time since you will be able to get to both sides of it. Any oil and dirt that gets back there reduces airflow.

A good radiator is the key to a long lived 8V92.

[Wally Arntzen]

There is an allison dealer in Blaine, MN which is about 35 miles south of Cambridge on hwy 65. The Main Allision dealer is in Bloomington right next to the Meg Mall.
My transmission went out on my 88 about 4 years ago right after I got it and it cost me 7500.00 bucks in Witchita, Kansas. Good luck and if you get it check out before you burn it up maybe they can fix it at much less cost.

[Wally Arntzen]

There is a Detroit dealer in Blaine next to the Allision dealer. There is a place in Ham Lake which is on hwy 65 about 15 miles south of Cambridge called Verns Service. He is an expert on furnaces, air conditioners, refrigerators, etc and he is very reasonable on cost. His number is 763-434-6165, if you call him tell him I gave you his number and you need help right away because your on your way home.
The Detroit dealer should be able to help you with the radiator but they are pricey.

[hlfdzn]

Latest update...

It looks like it may not be the tranny, but rather the engine isn't achieving the RPM's it should. At rest I'm only getting 1800 but that seems to increase as it warms up. After talking with the Allison/Detroit shop down in Bloomington that Wally and Newell recommended they shifted me from the Allison folks to the Detroit folks.

Right now we're heading down to Vern to have him check out the furnace and also to see if driving the coach without the toad makes any difference. I'm watching VMSpc with eagle eyes to make sure my temps remain okay.

Michael and Wally, I so appreciate you taking the time to help me with your advice.

More later....

[fulltiming]

Try changing the fuel filters first. I had a secondary fuel filter that became plugged with slime and the engine would starve for fuel, then the DDEC would cut back the turbo boost. Certainly that is the less costly fix. Could have a fuel pump going toes up.

Past that, I guess you could have an injection rack that has slipped out of adjustment and will no longer open fully. Other options are much more expensive.

[hlfdzn]

Just got back from Vern's. What a great place! This is a mom & pop outfit that gives the kind of service that few produce today. Ben & Mary took care of us and fixed and checked both furnaces. Turns out the only reason the front furnace wasn't working was the electrode was corroded and not spaced to specs. He put in a new one and then cleaned up the old one for a spare. He was so knowledgeable and prices so fair I asked him to check the other furnace and fix some other things. I still walked out paying just over one bill. Thank you for a superb recommendation Wally!

After speaking with Creslie at Newell, I'm leaning towards the thought that the turbo blew something on one of the connections. Micheal, I will check the fuel filters and would love to find that as the problem. The reason the turbo is suspect is because of the low boost, but also, that the damage to the radiator is in an unusual location (top of the rad finned area) for it to be road garbage that got sucked in, but is exactly where something coming off of the turbo would have hit. I've done some looking at the turbo and in the bottom of the radiator housing for pieces but haven't found anything yet. I'm thinking that since I have to take it to a shop for the radiator, I'll have them check it out. We won't be able to get it in until a week from now, so I'm going to continue to see what I can find myself. Please let me know if you think of anything else.

While looking in the engine bay, I found what may be contributing to the lack of dash heat. The hose that runs from the engine to the coolant pump runs along the top shelf above the house batteries and has a gash worn in it that is leaking antifreeze.

Thanks again for all the help you guys!

Til my next update,

[fulltiming]

Paul,

What kind of boost were you seeing when the vibrations and failure to pass 1800 rpm occurred? A turbo that has blown would leave debris everywhere if the case were penetrated and if the case were not penetrated, the parts would be lodged in the blower directly below it and/or tossed through the exhaust and/or intake side of the blower. That would be a MAJOR problem so lets hope for something less Draconian.

My boost which will typically run 24 psi on full throttle would not exceed about 16 psi when my secondary fuel filter was plugged. I suspect that a fuel pump going south would also cause the DDEC to cut back the turbo boost.

Glad you found an inexpensive way to deal with the front furnace. Did they have to remove the coach to get yours out? I haven't found any way to gain access to mine other than removal of the couch OR removal of the laminate couch base.

[hlfdzn]

Hello Michael,

My boost seems to be responding similar to yours. I haven't yet checked the filter but will shortly. The turbo itself seems fine, but Creslie mentioned that if one of the hoses to the turbo is broken or loose, I'd see the same symptoms. If it is the filter, the next thing to resolve is what caused the damage to the radiator.

The front furnace is under a fold out couch with a door that folds down in front of it, so access is very easy. All Ben had to do was drop the door and remove the cover and the electrode. Sounds like yours is much more problematic.

Our rear furnace will be very difficult to remove as it has a solid shelf over it and the carpet is built up in front to prevent any removal without some cutting of the carpet and other disassembly.

[encantotom]

hi paul, what furnace does your coach have? i have the duotherm 90130-6 and they are doing the exact same thing as you describe. i am about to take them out and look at them.

i might call verns for some advice.

good luck on your engine challenges.

tom

[hlfdzn]

Hello Tom,

My furnaces are Suburban NT-30K's. I'm happy to send any business Vern's way I can.

[Wally Arntzen]

Hi Paul, I'm back in Minnesota for a few days and am close to your relatives in Cambridge. If you are still here and want to get together give me a call at 612-810-2655.

Thanks much, Wally

[hlfdzn]

Replaced both fuel filters this weekend and afterwards the engine seemed to respond normally with RPMs up to 2500. Didn't want to take it out due to the snowfall. Normally I'd just fill and replace the filters and then start it up, but I followed Micheals excellent write-up from the Engine Bucking thread and it worked perfectly. Thanks again Michael.

Today had the pleasure of meeting with Wally and we went down to a Bus repair place called C&J that he highly recommends in Minneapolis area. I was very impressed with them and their knowledgeable friendly service. Afterwards we came back to where we're staying and took out the coach to see how it ran.

There was no hesitation, the turbo boost responded as expected and the transmission shifted smoothly. As Michael said, it was the filters. I still have to have the radiator pulled and repaired and am trying to figure out what could have caused the damage if it wasn't something from the engine.

I'd like to thank Wally for taking the time to meet with me and then drive an hour south to show me C&J's and then back up where we're staying. We had a wonderful time together and look forward to meeting up again soon.

I also want to thank Michael for the time he took to diagnose the problems with our Newell and also all the time he has spent helping all of us on this forum.

I'll let you know how the radiator job goes. If any of you have had your radiators pulled & repaired, can you give me an idea of what it ran you?

[Richard and Rhonda]

Michael,

Just curious, did you see any codes on your VMSpc when the fuel filters got clogged?

[hlfdzn]

Michael,

I'm interested also. I never had a peep from VMSpc on this specific problem.

This is the only thing I had pop up on this trip or even since I've had VMSpc:

SRC TPE ID MD COMPONENT MODE MM/DD/YY HH:MM
========================================
ENG PID 100 3 Engine Oil Pressure High Voltage 3/15/08 9:49

I ran a search on it but didn't come up with anything. It never happened again.

[hlfdzn]

Went to the shop yesterday and am optimistic with the outcome. The heater hose was a quick repair. After looking at the radiator, they didn't feel that it needed to be pulled especially since there haven't ever been any overheating issues with it. They recommended Justice Brothers "Stop-leak". I was dubious about using something this type product, but after giving Newell a call went ahead with it. Years ago, I remember the stuff that existed was horrible for clogging the engine and only a temporary solution. Apparently technology has progessed. Also, the leak is at the very top of the radiator so minimal coolant was leaking.

I'm still going to pull the radiator, but when I have time to pull it myself and the shop can take their time recoring it the right way.

We'll see if I made the wrong decision for this trip. I'll be keeping my eyes on the coolant temp & level.

[fulltiming]

Paul, hopefully the Stop-Leak will work for you.

Paul and Richard, no, I never had any errors displayed by VMSpc when the fuel filter when south on me. Just the bucking, the reduced boost and the lack of power.

Michael

[ttikalsky]

If your still in MN there is a shop in Cologne MN named Cooling Systems Services. Dan is the owner and does good work. I had the front heater core repaired and the price was reasonable and it was in tough shape.

403 Conrad Ave S
Cologne, MN 55322
(952) 466-5696

[hlfdzn]

Hello All, We arrived up here earlier this month. The trip up was absolutely beautiful. It's a rare thing to spend almost a week driving across Canada in March and have blue skies and dry pavement all the way.

The coach never gave us a problem again with the fuel filters or the radiator. The six coach batteries kept the coach heated all night long even down to 0 without needing to run the generator. We did run the generator each morning to provide enough current to the block heater to warm up the engine. 92's don't like the cold. I think if we had a diesel coolant heater installed, our generator use would have been reduced to few hours total on the trip for cooking. Fuel prices in Canada figured out to almost $5 a gallon and that was in March. I wouldn't be surprised to see $6 now. When road conditions allowed, top speed was 55-60 which gave me a high of 7.5 mpg and a low of 4.53. I haven't figured out the overall yet. The high was due to the flatlands of MN/ND and a tailwind. The low was due to headwind/wintergrade fuel/terrain. I was glad to have had the radiator leak-seal in the system not only due to the prior leak, but also as a preventative in case a piece of gravel got sucked through the screen and into the radiator.

We did have two new things pop up, the cable connection to the starter solenoid came loose from the inside and I had to hold the cable to start the engine otherwise it would ground, and one waterpump stopped working and the other was leaking.

Typically, the winter driving is more hazardous for the windows due to the use of gravel vice chemicals on the road surfaces. This was my third trip on the Alaska highway with the coach, but the first in the winter and we ended up with three rock chips. It was much better than I expected.

Thanks again for all your help and suggestions while enroute!!!

[fulltiming]

Sounds like a great trip Paul. Problems do sound relatively minor, all things considered.

I have been teathered for the past couple of months so I am envious.