Allison Transmission Questions

Discussion in 'General RVing' started by AllisonMan, Apr 5, 2003.

  1. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    The to cooler is the hottest point in the system. That's where you want the temp gauge to tell you the max temp the oil is seeing.

    Having the gauge in the from cooler port give you a pretty good idea of what temp the trans sump is running, but won't necessarily alert you to oil getting overly hot (300 deg F plus).

    The trans has a thermistor in the sump which will signal the ECU when the sump is either too cold or hot and the trans will react accordingly. Too cold (-20) and you can't get gear. When the sump starts to get hot (270 I believe) high gear will be restricted.
     
  2. ratherbflyn

    ratherbflyn New Member

    Re: Allison Transmission Questions

    Thanks, dbarton. So is there a pre existing port I can move the sensor to? It seems like there are a lot of bolts and a few drain ports on then pan, but none of the drain ports are close to the "to cooler" junction and all the bolts close to it appear to be mounting bolts. Or do I need to have a new one drilled and tapped in the "to cooler" junction/fitting?

    Is there a way to T off the stock sensor for the idiot light or is that a different type of sensor that will not yield temperature?

    Triple E, thanks for that info. That might explain why I never see much happening on my guage since it starts at 140 degrees. However, I have experience a trans overtemp idiot light and had the guage only registering low in the yellow arc (low temp 140-170 degrees). So I'd still like to move the sensor to a hotter part of the trans to make the guage more useful.

    Thanks,
    Doug
     
  3. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    What you need to do is put a tee fitting in the to cooler line itself. That is how this is most commonly done. Aeroquip is the brand of fittings I see in many applications. I'm sure there are others.

    The bottom of the trans on this model is not a pan. It is the cast aluminum base for the control module assembly. Do not try to drill and tap into it.

    It is not recommended to try to tap into the thermistor circuit to drive any gauge, light or anything else. The results are unpredictable.
     
  4. ratherbflyn

    ratherbflyn New Member

    Re: Allison Transmission Questions

    Thanks again dbarton. Good to know that's not a pan. So putting a T-fitting on the "to cooler" line implies there is already a fitting someplace on that line. Although I've only inspected the area around the coupling to the tranny, I don't see any fitting or port of any type. Would there be one closer to the cooler somewhere?
     
  5. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    I wasn't real clear. You have to add a tee fitting into the cooler line near the transmission. You'll need the services of a place that has a hydraulic hose crimper to section the cooler hose and add a tee fitting of the appropriate size.

    Another option is to find a fitting that goes between your cooler hose and the fitting that's threaded into the trans. That fitting should be a tee to put the gauge sending unit in.

    I have also seen transmissions that had an extended fitting threaded into the trans that was drilled and tapped to accept the gauge sending unit. The existing cooler hose connects to the extended fitting that threads into the trans.

    I know they exist, I have seen them. You may have to call a parker, or an aeroquip distributor to find the right fitting for your application.

    I did some quick googling and could not come up with a picture. I'll keep looking and see if I can some up with something that will help.
     
  6. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    http://www.aeroquip.cc/index.asp

    Here's a site I found. I searched on tee and found a whole bunch of aeroquip's tee fittings. Ideally, you'll need a male o-ring fitting on one end to go into the trans. A 37 degree flare to mate to your cooler hose on the other.

    The tee side of the fitting may be another 37 deg male, so you'll have to come up with the adapters to fit the sending unit. Or, cap the second 37 deg connection and drill and tap the cap. I hope this helps.

    If you call them and tell them what you're doing, they may have just the ticket in one piece, or be able to assemble something that will work.
     
  7. ratherbflyn

    ratherbflyn New Member

    Re: Allison Transmission Questions

    Ahhh, I think I understand now. I was thinking small port some where in the line, but you're talking about adding a T coupling inline to the 1 or 1.5" hose/tranny coupling. Looks like I'll have a professional do that.

    One more question then...I read some of the earlier posts and have talked to allison...it looks like putting the sensor there will mean hotter temp readings in the 300 degree range...is that correct? If so, my guage will be routinely sitting in the yellow (260+ deg) or red (300+ deg) arcs. Or is the 300 deg mark only hit when the tranny is on it's way to overheating?

    Thanks again,
    Doug
     
  8. Triple E

    Triple E Senior Member

    Re: Allison Transmission Questions

    Hello again, I have mine installed where db said to have it installed. The sensor is TEEed into the line from the transmission to the cooler which is a true reading of the temperature. I verified the calibration of my sensor with the gauge and it is within 1%. As I mention before I do not recall being any higher then 170 degrees. I am not sure what Allison is saying. From what I understand 300 degrees is the MAX temperature. Anyway, I would wait to install the sensor when you are doing your next oil change. ;)
     
  9. ratherbflyn

    ratherbflyn New Member

    Re: Allison Transmission Questions

    Thanks TE. That's a relief. Given the system would probably have to drained to do this, wait until the next change interval is probably a good idea.

    Thanks for the info, you guys have been really helpful.

    doug
     
  10. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    300 is the max. Triple E has it right. That transmission should only hit 250 - 300 to the cooler when it's being worked pretty hard. Most motorhomes will never see those kind of temperatures except if there's a failure, or they're severely overloaded. The output retarder is another story, but I don't think you mentioned having a retarder.
     
  11. ratherbflyn

    ratherbflyn New Member

    Re: Allison Transmission Questions

    OK, good. No, no retarder in my system. By the way, what are your thoughts on a pac/exhaust brake in my installation. It's a 34' MH, 19,000lbs GVW, cummins 5.9 230 HP turbo, MD3060.
     
  12. Raye3k

    Raye3k New Member

    Re: Allison Transmission Questions

    Thanks again.

    Say the engine is turning real fast going down the hill, do you have an idea of what vehicle speed or engine rpm would cause a change from 1st to 2nd and then 2nd to 3rd? or what would be the top vehicle speeds possioble in 1st, 2nd and 3rd gears going down a hill without braking?

    Thanks
    Ray
     
  13. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    Nothing wrong with a pac brake. They do require engine RPM to be efficient. You should interface one with the trans ECU. The Trans ECU can go to a preselect downshift schedule when the pac is active. It can preselect to either D4 or D2 to put you on a preslect downshift schedule which keeps engine RPMs up while the pac is on.

    I think the installation would best done by a pro with access to Allison DOC and a knowledge of the available calibration options for the trans. Just putting the pac on without interfacing with the trans is a lot of money for not much braking.
     
  14. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    I know enough to tell you you'd be in an engine overspeed situation to force an upshift out of a preselected range.

    As for top vehicle speeds, that depends on the vehicle. Can't really help you there.
     
  15. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    Why do you ask? Do you have a vehicle that does this?
     
  16. briggsey1

    briggsey1 New Member

    Re: Allison Transmission Questions

    briggsey1
    Hi sorry to jump in but I am having a problem with my allison trans and would like some help. I know next to nothing about these things. Here is my problem I recently moved to a new park and I believe I inadvertently turned the enigine off with the trans in reverse. Now the engine will not turn over and when the key is turned on the shift pad does not light up, the check transmission light is on, and the warning bell is going off. We have tried disconnecting the chasis batteries for at least 1/2 hour. and have replaced the 10 amp fuses in the box next to the TCM. We have also replaced the 4 relays in that box. Also, one of the chasis batrteries was weak (reading 2.5 volts) so we replaced both batteries. We have battery power to the TCM and to the wiring connector under the shift pad. We have also checked the ground to the batteries. I probably need to mention that the rear wheels are off the ground. (We were in a temp space until our actual space was ready) Someone said that the trans is hung up and needs to be "jumped", I don't know what this means and if it's a possible answer could someone explain to me how it is done. If anyone has any thoughts, ideas, solutions, or SWAGs I would appreciate the help. Iapologize for jumping in but I couldn't figure another way to post this.

    Thanks
    briggsey1
     
  17. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    To the best of my knowledge, turning the key off in reverse by itself doesn't cause such a problem. When the power is turned off and the engine stops, the trans goes to neutral. When the ignition comes back on, the selector wakes up in neutral.

    This is most likely not a problem with the trans hardware itself. This is a no-start problem and should be worked on as such, so it may involve trans wiring interface to the vehicle, the engine starter circuit, neutral start, etc.

    Engine that can't turn over, shift pad not lighting up, and check trans light on indicates ignition power not getting to somewhere it belongs.

    You said the ECU has power, make sure it has ground. Gotta then make sure the ignition switch and the selector are getting power, ignition switch is feeding power to the ignition input to the ECU, the ECU is grounding the neutral start signal to the neutral start relay and the starter solenoid is getting power.

    If you're working on this yourself, I would highly recommend getting an Allison troubleshooting manual so you'll have at least the schematic for the trans interface to the vehicle. I believe they can still be ordered at www.allisontransmission.com, service, publications.
     
  18. 2slo

    2slo New Member

    RE: Allison Transmission Questions

    hey guys. I have a 2002 duramax chevrolet. out of no where i have no speedo, and the truck shifts to neutral if i go about a slow crawl, about when the speedo would start to read. has anyone ever ran into this?! this is my daily driver so any help is appreciated. if you do have info, feel free to call my cell phone asap 314 503 7586. Thanks!

    Randy
     
  19. downard1

    downard1 New Member

    Re: Allison Transmission Questions

    Hey dbarton291, or allisonman. I've been checking since I've had time lately about the switch from the MT643 to the MD3060. Williams DD in Columbus is in over their head, maybe. I spoke with the service rep and he didn't think it could be done, until I told him that there are folks on this site who have RV's running the same set up. I had a friend who runs a truck shop check with another service rep, and he indicated that they (Williams DD) don't have the tools to set up the transmission in the way I'm looking to do it. i.e. with a TPS. As the truck I'm pulling the tranny from has an electronic Cat in it, they seem to think that my donor transmission is communicating directly with the engine ecu for engine speed since it's an electronic engine. Doesn't the transmission pick up engine speed from a pickup on the input side of the tranny. Any way, I am assuming that what they are saying is, if I do get the tranny installed into the truck, they don't have any way of programming the transmission. Why, I haven't a clue. They suggested that I find another engine/tranny setup similar to what I am trying to do and get the serial number from that trans and ecu, then there is a chance they can get the appropriate information.

    To anyone else out there who has an rv with a mechanical 8.3 cummins mated to an Allison MD3060, could I get the make and model of your RV. Also, it would be helpful if I knew who you either bought it from, or who you would take it to for service of the transmission, since Columbus, Ohio doen't have the capability to work on such a setup.

    Help please.

    Thanks in advance.
     
  20. downard1

    downard1 New Member

    Re: Allison Transmission Questions

    Oh yea, the trans ecu is a WTEC II. I have confirmed that.
     

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