| Author | Message | ||
| Stephen (Mohave_steve)
Registered Member Username: Mohave_steve Post Number: 1 Registered: 7-2007 Posted From: 74.32.81.113 Rating: N/A |
Hello All, I have an 1980 Eagle Model 10 with an 8v-71 & Allison HT 740. Over time the mechanical throttle linkage has gotten quite stiff and I have wanted to add a cruise control. As the coach has been sitting for some time and I am preparing to put it back on the road I decided to have an air throttle installed. A local mechanic installed the air throttle & transmission modulator. When I took the coach out for a test drive all seemed normal at first. Then after several trips around the block, each trip involving 1-2 stop signs, I approached a stop, the coach began to buck then the engine died. Shifted t neutral started the coach, put it in gear, coach lurched and died. After several tries I managed to get the coach rolling and limped back to the house. I crawled under the coach and found the modulator hanging by the air line. I removed the mounting clip & replaced the modulator. No change in the proble. I later found that the pin that sits between the modulator and the vaulve body was missing. Replaced the missing pin. No change. Symptoms: 1) Coach lurches & engine dies when put in forward gear. 2) No reverse. Mostly...I did after several tries get reverse once yesterday but could not repeat. Local mechanic thinks it MAY be a bad torque convertor or a problem with the vaulve body. He is a pretty sharp guy but not quite an Allison Guru. Any suggestions?? Thanks Steve | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 198 Registered: 8-2006 Posted From: 74.33.62.149 Rating: N/A |
Steve, call Bob Ware at 1-888-935-3335 S&J Chevrolet best Allision person in the USA if he hasn't retired also call the shop foreman at United Transmission at 1-800-527-1637 the one i knew got old like the rest of us. Hope this help you let us know what Bob thinks.Do you live in Mohave Valley AZ (Message edited by luvrbus on December 06, 2007) | ||
| Stephen (Mohave_steve)
Registered Member Username: Mohave_steve Post Number: 3 Registered: 7-2007 Posted From: 74.32.81.113 Rating: N/A |
Thanks Luvrbus, I will give them a call! & yes I am in Mohave Vally. I am suprised that anyone more than 20 miles frome here has ever heard of Mohave Vally... We call it "Purgatory". It's not quite Hell but you can feel the heat from here  Thanks Steve | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 199 Registered: 8-2006 Posted From: 74.33.62.149 Rating: N/A |
I,live around the corner from you on South and Callie I met you about 4 or 5 years ago at the AVI RV park.trust Bob he knows his stuff | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 812 Registered: 11-2004 Posted From: 72.91.168.92 Rating: N/A |
Sounds like its stuck in lock-up - FWIW | ||
| Debbie and Joe Cannarozzi (Joe_camper)
Registered Member Username: Joe_camper Post Number: 76 Registered: 10-2006 Posted From: 71.239.202.82 Rating: N/A |
That could be an unrelated problem to what your local guy did for you but I doubt it. | ||
| Stephen (Mohave_steve)
Registered Member Username: Mohave_steve Post Number: 5 Registered: 7-2007 Posted From: 74.32.81.113 Rating: N/A |
Well I am not entirely certian but it it looks like it was simply a matter of the pin that sits between the air modulator & the modulator assembly being installed incorrectly. The transmission is now shifting properly but I am not sure I am getting full throttle. The bus is very sluggish and at one point during my brief test drive today I had full throttle (pedal) and was holding about 1400 rpm & 25 mph on level ground... What now........ | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 208 Registered: 8-2006 Posted From: 74.33.62.149 Rating: N/A |
Steve,is there a adjustment on the air modulator thats the way mine was when it was out of adjustment but its a cable modulator | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 695 Registered: 12-2000 Posted From: 76.3.169.171 Rating: N/A |
Check that the air throttle is opening the rack all the way. May not have enough air pressure to the air throttle or the air throttle actuator arm on the governor may need adjusting. With engine running in neutral, a full throttle application should give you full RPM. If not, it is a problem in the air throttle system. Our air throttle modulator has no adjustment on it, but the instructions were very explicit that from the TEE fitting in the engine compartment, the lines to the modulator and the air throttle actuator should be exactly the same length. Hope this helps, Jack | ||
| Stephen (Mohave_steve)
Registered Member Username: Mohave_steve Post Number: 6 Registered: 7-2007 Posted From: 74.32.81.113 Rating: N/A |
Thanks for the replies. There is no adjustment on my modulator. I am able to get 2100 RPM in neutral at full throttle. If I understand your statement that woudl indicate that we ARE getting full throttle...I did follow the instructions regarding the "T" to a "T" The lengths of the air lines from the T to the modulator and to the throttle are within 1" of being the same length. The line from the treadle to the T is 3/8. All in compliance with the instructions that came with the air throttle. I know... I am bad... I have not driven the coach on the road in over two years. I have started it and moved it a short distance on the driveway but this is the first time on the road in quite a while. Could there be something related to it sitting that could be causing this? The engine idles & runs smoothly & does not show any unusual smoke. | ||
| Dan West (Utahclaimjumper)
Registered Member Username: Utahclaimjumper Post Number: 81 Registered: 1-2005 Posted From: 208.66.38.60 Rating: |
With that length of time, I think I would be looking at the fuel filters for low power problems.>>>Dan | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 696 Registered: 12-2000 Posted From: 76.3.169.171 Rating: |
I agree with Dan, If you can get 2100 RPM with no load and only 1400 RPM with a load, it sounds like you are not getting enough fuel. Jack | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1132 Registered: 12-2000 Posted From: 76.68.122.208 Rating: N/A |
Hello Steve 2100 rpm in neutral is easily achieved with only a small throttle opening, and plugged fuel filters. It only takes a very small amount of fuel to spin the monster to the governor unloaded. Can't get an open exhaust to bark as loud sitting still as pulling away....less bang going on! Start with the simple and routine, then get more complicated. Change out the filters, which you want to do periodically anyway, and see what happens. I am a big fan of energy conservation. Others call me lazy... And, of course, report back! happy coaching! buswarrior | ||
| Stephen (Mohave_steve)
Registered Member Username: Mohave_steve Post Number: 7 Registered: 7-2007 Posted From: 74.32.81.113 Rating: N/A |
Well it turns out that I was not getting full throttle. I contacted the people I bought the air throttle from and they said I should be getting 1" plus of travel from the slave. I was only getting 3/8". We dissasembled the slave and found that there was no way you could ever get 1" travel. The cylinder is only 1" deep and the piston that travels in it is over 1/4" thick. We did find that the threaded rod that exits the slave cylinder was not allowing the piston to return all of the way back in the cylinder in the relaxed position. It was "preloaded" taking up about 1/4 of the available travel. Some adjustment allowed us to get about 5/8" of total travel. Put everything back together and IT WORKED!! Woo Hooo! Enough acceleration to break dishes!! Well OK, I only broke one..... Now.... 30 minutes of driving and my coolant temp is 125.... Maybe it's the FRIGID weather (It's only 60 outside). I think the fan is staying engaged even when the engine is cold. I know the cooling system continues to flow a certain amount of coolant even when the thermostats are closed. Is the fan running and the small amount of coolant that bypasses the thermostats enough to keep me from reaching 170-180 when ambient is 57-60? Also, Buswarrior, what is that white stuff all over your bus? | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1134 Registered: 12-2000 Posted From: 76.68.120.120 Rating: N/A |
Hello Steve. Dandruff? Somebody up There has a bad case 'round about this time of year, regular like clockwork... Which gauge are you reading this 125 degrees on? The electric dash gauge may not be accurate. Check to see if you have a mechanical one in the engine room somewhere. Also, purchasing one of those infrared temperature guns is a great investment. Under $100, one of the best tools you'll own, after your big hammer! Everything mechanical shows the early signs of problems through heat. Tires, bearings, radiators, air conditioning, heating systems, the uses for a busnut in studying the "project" are almost endless. And, the temp of the refrigerator for enjoying refreshments... happy coaching! buswarrior | ||
| Stephen (Mohave_steve)
Registered Member Username: Mohave_steve Post Number: 8 Registered: 7-2007 Posted From: 74.32.81.113 Rating: N/A |
Dandruff??? Hmmmm... I seem to remember seeing it before...It was all over those big green things... I think they called them "trees". Down here we have sage brush, cactus, sand & dust........ I checked the temp on both the dash mounted electric and the engine mounted mechanical. They were relatively close. My suspicion is that the fan running full time is the culprit. My mechanic says that is not likely. However, I do remember when I was a kid & my father drove truck he would tape cardboard over part of his radiator when the Dandruff fell . If I remember his explanation it was that even with the thermostats closed some coolant continued to flow and the engine would not get warm as there was continuing air & coolant flow through the radiator. I do have an IR gun & will triple check. Thanks Steve | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 196 Registered: 8-2004 Posted From: 69.143.38.76 Rating: N/A |
Mohave Steve wrote "Dandruff??? Hmmmm... I seem to remember seeing it before..." __. Steve, he's having you on! It's called "snow" -- I know because we have even more of it here in Eastern NC than they have in Canada! Between that and our house prices being higher than Westchester County and taxes being higher than Bergen County, all Northerners need to understand that they should move to Georgia or Texas or Florida (although they do have Florida pretty well filled up) -- AND NOT HERE! __. Now that we've finished the message from the NC Bureau for Prevention of Yankee Emigration, I'd suggest that you do a lot of "before and after" checks with your temp gun. Check both ends of hoses, the housing on the engine side of the thermostat and then immediately after the thermostat, inlet and outlet to the radiator, etc. Often you'll see a spot that's not looking right and that will give an indication on where to investigate further. __. BTW, what locks up your fan drive? Mine (probably very different from what anybody else has) has an electric clutch. On mine, it's possible to have a mechanical failure that's not related to the electrics, but usually a problem with the electrical stuff will give an idea of what's going on. Even if yours works some other way, I'd check the fan lockup. Also, how long has your thermostat been in there? They've been known to stick. Good luck, BH NC USA | ||
| Stephen (Mohave_steve)
Registered Member Username: Mohave_steve Post Number: 9 Registered: 7-2007 Posted From: 74.32.81.113 Rating: N/A |
Bruce, I like it!! "NC Bureau for Prevention of Yankee Emigration" My fan clutch is air controlled and there is a temprature controlled air vaulve that supplies air to unlock the clutch. My mechanic disconnected the air line in order to cause the fan to run full time. BTW: I have considered moving to Oriental. Pretty place... |
