I have a 1997 U295, after purchasing it two years ago I did a complete service on it myself. When flushing the coolant system I noticed a pin hole leak in the tranny cooler. I bought a new one from Ice Box Diesel. I sent a fluid sample to Blackstone and it came back no trace of glycol in sample.
We made a 1700 mile trip pulling a toad through the Smokies with no problems last summer. We used it close to home several times and this past June we headed over to NAC to meet up with some friends and get new shoes on the coach. I live about three hours from NAC and when we got to town my tranny light came on. In hindsight, I should have stayed and had it looked at but I didn't want to ruin our trip as we had four in convoy to Hot Springs. We made it about three hours before the light came on again. We pulled over at a truck stop for 15 minutes and continued on to HS fine.
After our stay we left for Broken Bow and had no problem. We left BB a few days later and had to stop 4 times on our way home, a 5 hour drive. What's strange is I can pull over a kill it for 5 minutes and then continue on for a good while before it heats back up.
I made a huge mistake by taking it to United Engines in Shreveport to have it fixed and after $3500 they couldn't figure out what was wrong so I'm at a loss as to what to do now.
Do any of you have a clue as to what could be going on? Or have you ever seen something similar?
As a side note, the retarder doesn't work but it hasn't worked since I've owned it.
Any help would greatly appreciated.
Thanks, Mike
What is the trans temp gauge say when the heat light comes on?
What is engine temp at same time?
What is the grade of the road at that time?
What gear is trans in ?
Heat comes from friction or it is transfered to the trans
If you have an infra red heat you see if the lines coming out of the trans actually hot. Maybe a gauge or sender
Light comes on around 220. Engine temp runs at 180 and doesn't rise. It will do it on flat interstate running is sixth gear.
I've shot the sump with infrared gun and it shows 250
Tech hooked lap top to tcm and it shows overheat on four occasions
Think the first thing I would find out is whythe retarder does not work,are there lines disconnected
Or what,you would think the tech would have wondered also.When were the filters and fluid changed.
I did a complete service on the coach, including the trans, new filters and Transyd 668.
The 163 wire is showing no voltage. The shop asked me if I wanted them to trace the wire down but when they told me how much time they had spent on it with no results, I decided to go get it, I had no confidence in their ability. It seems to me they wanted to swap parts until it was fixed. I wasn't going to pay for them to experiment.
How do I trace down the cause for no voltage on 163? Is this the wire that connects to the accumulator?
The schematic linked below is found in our excellent Forum Library/Schematics folder. If you rotate it 90 degrees to the right so it is in landscape orientation, then you'll find wire 163 at the top right hand corner.
Check wire 5 coming into the retarder switch. From the diagram (above) looks like it should be HOT with Ignition Switch turned on (RUN position).
Yes, I know the schematic is for the 4000MH tranny, but the 163 wire origin should be the same for both models.
https://www.foreforums.com/index.php?action=media;sa=media;in=3282
Thanks
Have you personally checked the fluid level after the change?
Fluid level shows Ok on Allison shift pad
I'd give Keith Risch in NAC a shout. If anyone can track it down he can.
kwrisch40@yahoo.com
I've talked with Keith about it, he happens to be a friend of my bud that went to Hot Springs with me. If I can't figure it out I'll definitely be taking it back to NAC. Thanks
Have you checked for DIAGNOSTIC CODES?
Something as simple as torque converter not locking up can cause overheating.
Can you shoot both ends of the trans cooler to see if you have a temp difference,if that sump is actually 250 the internal parts are a whole lot hotter.
The shop I took it to did a flow test and a temp check. The cooler drops temp 10 degrees and Allison said that was in spec. Also flow was in spec.
The only codes showing where high sump temp.
I have little knowledge of this subject, but from a purely amateur perspective, a measly 10 degree reduction in fluid temp seems hardly worth the trouble/expense of having a cooler.
If it,s in spec it,s in spec,from reading every post over and over it seems that for some reason
Under normal conditions the trans is getting muchhotter then normal,plus if the retarder was working it would be hotter,do you have the joystick or the rocker switch.
The IRV2 thread linked below may be of some interest for general comparison purpose. It seems 3060 trans temps are all over the chart, depending on vehicle cooler setup and where the fluid temp is actually measured.
3000 Allison Temperature - iRV2 Forums (https://www.irv2.com/forums/f125/3000-allison-temperature-423243.html)
If this was on an M-11 I would say that the water pump bypass orifice has been left out of the system. When you did all the fluids did you replace the water pump also? Reason being you could have a bad/eroded impeller not delivering proper flow. That cooler should have a lot more differential between in and out.
Retarder problem, Have you checked the retarder relay (hid behind the kick panel in front of the passengers seat) and the retarder on/off switch (here is where the163 wire comes from)
Mike
I'm with you, 10 degree drop doesn't seem to be enough but according to Allison, it is.
I have the rocker switch and a joy stick. The light comes on on the rocker when you back off the throttle when switch is on.
I pulled the relay and tested it and it's ok.
I read that thread, the post about 200-230 being ok is disturbing, there's no way it can survive at those temps.
Bad gauge?
That's been ruled out, I wish it was that simple.
Actually with the newer Allison fluids, particularly the new Transynd 668 those temperatures are not a problem.
But, look at the fluid path from water pump to the transmission cooler. As already posted, some applications have a restrictor to direct more coolant flow to the transmission cooler.
Maybe others can chime in that have your setup,we just have the rocker switch,when you turn it off
no retarder,when on and you use the brake the light comes on in other words when the light is on
the retarder is on and in use.
On my 95 3060R, trans temp runs with engine temp. On mine thermostat temp is 181. According to conditions my engine will run 200 - 202 a lot of time in the summer months. If retarder is working during normal stop at red light from 60mph, trans temp will go to 220 for a short time. Using retarder on down grades will also send trans temps above 200 quickly.
Just throwing this out there but could Scubas retarder be on all the time causing the overheat?
I had to replace my transmission cooler on my 2001 a few years ago. I found that it was not cooling or even coming down fast enough after going up high. I found a bit of the weld had broken off inside after having it removed.
The single wire that plugs into to the module on the accumulator, I've been told to unplug it and drive it to see if it heated up. What's your thoughts, if the retarder was dragging, I could see where it would build heat. Will this isolate the retarder or am I wasting diesel?
Is it possible that the disconnected retarder is operating constantly/ permanently in the lowest setting, which would be barely noticed yet would be loading the transmission?
On my coach the ABS controls the clutch lock up and retarder. ABS failure could cause clutch to not lock up and overheat the transmission and cause the retarder to be inoperable.
I do have an ABS light on, I didn't make a connection. I guess that could have something to do with it. The only thing is, the ABS light was on when I bought it and we've made a long trip with no issues last year. I'll call Risch tomorrow and see what he says. Thanks for the post, you may be on to something.
Do you feel the "mini-shift" at higher RPM in 2nd gear? That is when the torque converter should be locking up as you accelerate.
I don't, but the tech at United Engines in Shreveport drove the coach and said that he detected no problems with the function of the transmission. But he also didn't say anything about the ABS light being on either.
The only code the TCM showed was high sump temp. Wouldn't it throw a code if the converter wasn't locking up?
Sorry, don't know the answer to that one. You could certainly ask Allison (have your transmission model and serial number handy):
Allison help line 800 252 5283
Open your ABS control box and unplug the power connector. Check to see if you have retarder function restored and check clutch lockup.
Would you be so kind as to tell me where the ABS control box is?
Thanks
On your '97 it should be hid in the basement behind the HWH compressor. Should be the 2nd bay on the drivers side of the coach behind the front tire. Some are on the wall and some were mounted on the celling of that basement bay. Look for a grey box that is about 8" square and 3" thick.
Mike
It's in a really tight spot, I can't get behind it to try to disconnect power, I need both hands back there. Any suggestions?
Wondering if this ABS issue could also be affecting my tranny heat issue.
By chance does anyone have the ABS box location for a 2001 U295?
Also, would leaving the Retarder turned on offset the ABS issue ?
Completely disconnected the ABS box. Still having the overheating issue.
The tranny and retarder only got up to 199 today, but I believe that's because the ambient temperature was down.
Tranny is running about 12 to 15 degrees hotter than the radiator. Tranny ran 196 to 199 while motor was mid 180's.
Doesn't matter if the retarder is on or off. When stopped and idling, the tranny temp drops quickly to the motor temp.
Stumped on this one. Good news is the forecast is for relatively cool temperatures for the next couple of weeks and should keep the temps down.
I'll try to find a good Allison shop in Northern Colorado when I get back.
After taking the coach to a shop in NAC, it's still running hot. They basically did nothing but waste my time.
Everything points to insufficient cooling. I'm going to go with my original idea and add an air to fluid oil cooler in addition to the fluid to fluid cooler that's on there. I've figured out where to put it so I can use the return line from the original cooler to run to the new unit and have a short run back to the transmission. I plan on controlling the fan with a 180 degree on and 165 off switch. I'll post my results when I get it finished.
If fitting a second transmission fluid cooler, put it IN LINE BEFORE the OE cooler. You can over-cool ATF as well.
This routing will reduce heat load on the "cooling package" and insure that the ATF is not over-cooled.
But, since this is a very unusual issue, you are fixing a symptom, not the cause. Not necessarily bad, but......
Are you 100% sure the tranny cooler from Ice box diesel was the same size cooler,agree with Brett,the trans is getting abnormally
hot for some reason.If the trans was not getting hot with the old cooler then the new cooler is the problem.
Dimensionly they are identical, although they are not constructed the same.
Any engineering/BTU specs on either???
When I had my cooler cleaned and tested the tech told me they don't make them like this
anymore.
It has been long ago but it seems like Garry O had a similar problem and had to pull the control module out of the bottom of the trans and have it repaired. In my search I haven't been able to find the old thread that talks about his trouble yet.
Now with you living around Alex. LA. your go to place for trans work would be S & S in Longview, TX as they do a lot of Foretravel work. Longview | Stewart & Stevenson (https://www.stewartandstevensonservice.com/longview/?AdGroup=Brand&AdGroupId=1355698397396423&AdId=84731493111350&Campaign=Stewart%20%26%20Stevenson_MS_Search_Branded_Longview&CampaignId=407286315&Network=o&identifiers=kwd-84731802072535&utm_campaign=Stewart%20&%20Stevenson_MS_Search_Branded_Longview&utm_content=!acq!v3!1355698397396423_84731802072535_84731493111350_c&utm_medium=cpc&utm_source=bing&utm_term=stewart%20stevenson%20longview&msclkid=87c45a4eb87519d839a43f658ffb793c)
I will keep hunting for the thread as it is here somewhere.
Mike
Thanks Mike
Does anyone know the difference between part # 31259-A and 31259-B? I called the mother ship and got the part # for my original cooler and it is the B. I have found a remanufactured one but it is an A. Help please.
First mention:
Transmission Trouble in Omaha (https://www.foreforums.com/index.php?topic=12858.0)
Full topic:
A very rare transmission story (https://www.foreforums.com/index.php?topic=13654.0)
Some mention of the module, but also note that there was a section of retarder housing gasket missing.
Well, problem solved! The problem was the aftermarket cooler from icebox diesel that I installed shortly after buying the coach.
Thanks to Rudy Legett for contacting me and putting me in touch with Expert Transmission in Huffman Texas. These guys are who you want to deal with, super nice and very helpful on the phone. I highly recommend them.
My suspicions were right all along, the cooler I bought just couldn't handle the load. While explaining the issue to Jerry at Expert, he told me that they just happened to have an OEM cooler on the shelf. They are only 4 hours from the house so the DW and myself got in the car and drove over and picked it up. Problem solved! Tranny runs nice and cool now and I am thrilled.
United Engines in Shreveport La. charged me $3500 and couldn't figure out the problem and they are an Allison Distributor. Also One Way Diesel in Nac was of no help. I'd stay away from these businesses if I were you. Thanks to all on this forum who responded on this thread, my coach is fixed and I can use it now, hopefully we will see you on the road somewhere.
Mike
MIke,
We really appreciate members who come back and tell us the final "end of the story" on threads like this. You not only satisfy all the armchair mechanics (like me) who endeavor to learn something from other people's experience, but you also repay the members who jumped in with suggestions - whether they were helpful or not. One of the great benefits of this Forum is always having people available who want to help - no matter what the problem. We may not always have the correct answer, but we do the best we can. When you take the time to tell us the final solution to your problem, we all benefit from the additional collective wisdom.
PS: Looks like John44 (Reply #45) wins the prize for "Best Suggestion". ^.^d
Allison 3060 over heating (https://www.foreforums.com/index.php?topic=46828.msg476714#msg476714)
It is my intention to help others also. Hopefully this tread will save someone the headaches and expense I went through.
Sometimes the process of elimination is the answer and letting us know the good and bad places helps.
Glad you got it resolved. Ive always felt that a larger cooler would help in extended Retarder use. In looking at the manufacturers web page they do make one size larger cooler.(Longer) If I personally was replacing I would attempt to go to the larger cooler. It gets stupid hot here in southern nevada and a little more cooling has been appealing to me. Would require a different mount also. The new coolers are also three piece aluminum. This may be good or bad, I dont know. Think I'll run what we have for now. Thank you for posting your resolution. Glad to know im not the only one to induce my own problems, but with good intentions.
Thanks for posting your solution.