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Overheating Transmission now being told needs replacing


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So my 2003 Signature which I have owned since new, I was told by the main Allison dealer here in the Chicago area , needs to have a new transmission installed. (Ouch) The transmission is a Allison HD4000MH and the engine is a Cummins ISX525. My coach has 60k on it and I have always stored it indoors and heated indoors during the winter. I have the coach serviced regularly by my diesel mechanic and had the oil in the trans changed at least twice since owned. I know that the last time the trans oil was changed we installed "Transynd" . I have complained to my diesel mechanic that the trans temp seems to run high.  I will see temps on the road for the Trans read on my digital readout get up around 240. Which is 40degrees+ higher than my engine temp. I will drive 65-68mph and see these temps. I was told that the reason for the high temp could be the location of the digital sensor, The digital sensor does read about 10 degrees higher then the dash analog trans sensor. I even had my regular mechanic clean - wash the radiator to help improve the cooling of the radiator/transcooler.  To little to no help. So I have learned how to work with the hotter transmission. When outside air temp is hot and I am driving longer distances I will slow down 58-62mph. This would reduce the trans temp. If I end up in stop and go traffic I would shift trans to neutral as I coast or have to stop. This would help with cooling. Someone had suggested I take the coach to Allison to have the trans checked out. I made appt with Allison and they said it sounded like I needed the fluid and filter changed and I would be good. I told Allison my concern about the Trans temp and they said they will check it out after the service. After the fluid change they tell me the trans is still running hot. They need to yank the Radiator to check the cooling. They next tell me they didn't have to yank the Radiator, they were able to check the trans cooler and it works good. I get to speak to the Allison tech( who has worked there 20 years)and he tells me he has never seen a trans get this hot. Just an added note I have never noticed that the trans slips, runs out of gear or any performance problems. But breaking down on the road is the last thing I want to do. Anyone have any good thoughts or suggestions? 

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Posted (edited)

First thing is confirm that the trans is actually getting hotter than Allison recommends.  This could include getting a new temp sensor.  Since no problems, why mess with it.

How is your fuel economy?  6-8mpg?  Brakes not dragging / getting hot (you should have become aware of this way back)?

Radiator is motor temp.  Trans cooler is seperate.  Shared coolant so how goes the motor coolant temp?  Certainly if that is hot, then it can't cool the trans well.

You could always have an auxiliary trans cooler added.  No reason not to.

What's the spec for the trans temp?  Are we chasing normal?

Edited by DavidL
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I have the same tranny with a Detroit series 60. Mine will run close to 200 most of the time and get to 240 on long hill climbs. I was in AZ this winter with lots of climbing and never had any issues running 24-260. I think I would change all sensors before I spent the money on anew tranny. They should be able to look at shift solenoid, shift plates and lots of things that are easy fixes . I also changed all my filters and use transynd about 5 years ago. I think some time these guys think we are a gold mine to plunder. I don’t mean to bad mouth anyone but I get tired of guys scratching their head and telling me I need to spend thousands of dollars to find out what is wrong.

good luck

 

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Interesting,would be hard to argue a case against a person with 20 years experience in Allision transmission, 60k for mileage very hard to believe that there could be a problem with a bullet proof transmission, my temperature gauge stopped working,I have just over 100k and oil has been changed twice,no leaks nice and dry under transmission, I check it every time I am going to go out,I check it cold,always nice and clean, smells like it should,neutral in stopped traffic.i will get around to fixing the temp gauge but not worried about it, these transmission are in all types of heavy trucks and busses and can take a beating. I would be asking more questions, does not seem right.

It would be easy to say just drive it but it is always in your mind.

Hope it is a simple fix

Wayne 

1999 Signature ceaser 

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Sorry for your trouble. 

I agree on changing the temp sensors.  Has anyone done an oil analysis on the trans fluid after it's been run?

Usually, excess heat is from slipping either in the torque converter or the clutches.  But, it should be locking in 4th through 6th.  

And if they change the fluid again, I would use non-synthetic ATF at least until you find the issue.  No sense in wasting $500-$1000 on Transynd only to drain it and rebuild the trans.  Most commercial companies using Allison transmissions do not use Transynd, but they change the fluid on regular intervals.  

 

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Posted (edited)

On my coach the dash gauge gets it signal from a sensor mounted on an aluminum block on the hydraulic "out" port.   My dash gauge reads OK. 

I also have a Silverleaf that gets its info from the ECM.  I read quite a bit higher on the Silverleaf display. 

In 2015 I had a radiator failure and had a radiator built by CG&J.  We took one long trip right after the radiator install and I remember having high transmission temps in Albuquerque climbing a long steep grade but I forgot to downshift.  Didn't thing anything of it. 

Fast forward to last year, got my rig ready to roll but noticed the couple short trips I made I was seeing higher transmission temps.  I started to watch closely and it seemed my tranny was running about 10F higher then engine on moderate grades, would climb to 200F on steeper grades but if I got stuck in traffic my temp would go up to +220F.  I have to back into my garage and when I do this my temps go +230.

I started to get worried.  Sent an oil sample in and it came back good.  I flushed the tranny cooler, not problems there. 

I contacted CG&J and asked how they sized the tranny cooler internal to the radiator, the rep couldn't give me a good answer.  He offered to sell me an external cooler for $750.  I all ready contacted VanWill who had installed an external cooler for the tranny completely bypassing the radiator tranny cooler.  He gave me the info and sent me pictures. 

I decided to buy this  cooler from Derale. https://www.amazon.com/gp/product/B008VQGVSU?ref=em_1p_0_im&ref_=pe_3681270_622782040

I somewhat copied how VanWill installed his but opted not to bypass the tranny cooler internal to the radiator.  I had 2 good quality hoses made and plumbed it in.  The total cost was ~$ 550.  The picture is sideways and it is before I installed the switch.  The top port is the "IN" and I mounted the switch there. 

First test drive I took I connected the fan and let it run wide open but the temps never got above 135, which isn't good.  I then installed a 150F switch to turn the fan on and took it for a good long drive on the interstate which had some decent grades.  The temps never got above 180F and the fan never kicked on (I stopped and checked).  When I got back home and backed into my garage the temp only went to ~182F (in the past it went to +230F).  I even pulled forward and backed up a couple times to try and force it.  The fan would not come on.  I did some temp checks with the thermal gun and the temp of the fitting going into the cooler was 135F and coming out it was ~125F without the fan running.   So there was enough airflow to keep the tranny oil cooler.  I decided to install a 140F switch but have not had a chance to check it.  I set up my Silverleaf with a datalog on the tranny temp so I should see how it acts on the next trip, I live in E TN and any direction I go I have to climb some pretty good grades. 

Here is a picture of the cooler I installed.   I mounted in front of the engine, left side right below my remote start button. 

 

Derale Tran Cooler installed 2-17-2022.jpg

Edited by jacwjames
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7 minutes ago, jacwjames said:

On my coach the dash gauge gets it signal from a sensor mounted on an aluminum block on the hydraulic "out" port.   My dash gauge reads OK. 

I also have a Silverleaf that gets its info from the ECM.  I read quite a bit higher on the Silverleaf display. 

In 2015 I had a radiator failure and had a radiator built by CG&J.  We took one long trip right after the radiator install and I remember having high transmission temps in Albuquerque climbing a long steep grade but I forgot to downshift.  Didn't thing anything of it. 

Fast forward to last year, got my rig ready to roll but noticed the couple short trips I made I was seeing higher transmission temps.  I started to watch closely and it seemed my tranny was running about 10F higher then engine on moderate grades, would climb to 200F on steeper grades but if I got stuck in traffic my temp would go up to +220F.  I have to back into my garage and when I do this my temps go +230.

I started to get worried.  Sent an oil sample in and it came back good.  I flushed the tranny cooler, not problems there. 

I contacted CG&J and asked how they sized the tranny cooler internal to the radiator, the rep couldn't give me a good answer.  He offered to sell me an external cooler for $750.  I all ready contacted VanWill who had installed an external cooler for the tranny completely bypassing the radiator tranny cooler.  He gave me the info and sent me pictures. 

I decided to buy this  cooler from Derale. https://www.amazon.com/gp/product/B008VQGVSU?ref=em_1p_0_im&ref_=pe_3681270_622782040

I somewhat copied how VanWill installed his but opted not to bypass the tranny cooler internal to the radiator.  I had 2 good quality hoses made and plumbed it in.  The total cost was ~$ 550.  The picture is sideways and it is before I installed the switch.  The top port is the "IN" and I mounted the switch there. 

First test drive I took I connected the fan and let it run wide open but the temps never got above 135, which isn't good.  I then installed a 150F switch to turn the fan on and took it for a good long drive on the interstate which had some decent grades.  The temps never got above 180F and the fan never kicked on (I stopped and checked).  When I got back home and backed into my garage the temp only went to ~182F (in the past it went to +230F).  I even pulled forward and backed up a couple times to try and force it.  The fan would not come on.  I did some temp checks with the thermal gun and the temp of the fitting going into the cooler was 135F and coming out it was ~125F without the fan running.   So there was enough airflow to keep the tranny oil cooler.  I decided to install a 140F switch but have not had a chance to check it.  I set up my Silverleaf with a datalog on the tranny temp so I should see how it acts on the next trip, I live in E TN and any direction I go I have to climb some pretty good grades. 

Here is a picture of the cooler I installed.   I mounted in front of the engine, left side right below my remote start button. 

 

Derale Tran Cooler installed 2-17-2022.jpg

Great informative post.

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So yes the tech said he confirmed the high reading with a laser gun from under the coach. (His comment "I have never seen a trans get this hot in my career" -20 years at Allison) They supposedly have the coach up on a lift.  I have thought about an external cooler and have seen some of the posts here, but my regular mechanic poo-pooed the idea, thinking more of the issue was the location of the sensors. Still an external cooler might be the easiest and most cost effective option before replacing the trans. I have never felt the trans slip, lock up or misbehave. I plan to show up tomorrow at the Allison dealer before 2nd shift and talk to a supervisor and the mechanic. 

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My Coach has a separate Trans cooler that's the length of the radiator and 6 or 8" tall. I have not ever seen anything over 210 and that was four years ago climbing grades out of Phoenix at 110 ambient. And my engine has never topped 197 at the top of a long grade. I guess I'm lucky in that matter, not in others.

Tim  

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On 5/21/2022 at 12:58 PM, flyinghi said:

So my 2003 Signature which I have owned since new, I was told by the main Allison dealer here in the Chicago area , needs to have a new transmission installed. (Ouch) The transmission is a Allison HD4000MH and the engine is a Cummins ISX525. My coach has 60k on it and I have always stored it indoors and heated indoors during the winter. I have the coach serviced regularly by my diesel mechanic and had the oil in the trans changed at least twice since owned. I know that the last time the trans oil was changed we installed "Transynd" . I have complained to my diesel mechanic that the trans temp seems to run high.  I will see temps on the road for the Trans read on my digital readout get up around 240. Which is 40degrees+ higher than my engine temp. I will drive 65-68mph and see these temps. I was told that the reason for the high temp could be the location of the digital sensor, The digital sensor does read about 10 degrees higher then the dash analog trans sensor. I even had my regular mechanic clean - wash the radiator to help improve the cooling of the radiator/transcooler.  To little to no help. So I have learned how to work with the hotter transmission. When outside air temp is hot and I am driving longer distances I will slow down 58-62mph. This would reduce the trans temp. If I end up in stop and go traffic I would shift trans to neutral as I coast or have to stop. This would help with cooling. Someone had suggested I take the coach to Allison to have the trans checked out. I made appt with Allison and they said it sounded like I needed the fluid and filter changed and I would be good. I told Allison my concern about the Trans temp and they said they will check it out after the service. After the fluid change they tell me the trans is still running hot. They need to yank the Radiator to check the cooling. They next tell me they didn't have to yank the Radiator, they were able to check the trans cooler and it works good. I get to speak to the Allison tech( who has worked there 20 years)and he tells me he has never seen a trans get this hot. Just an added note I have never noticed that the trans slips, runs out of gear or any performance problems. But breaking down on the road is the last thing I want to do. Anyone have any good thoughts or suggestions? 

FWIW.  I have 65K on my 3000 and the ISL 425.  As to the temps, I rarely ever see 8 or 9 degrees differences.  I don’t have the intake Jake brake, so I really have to depend on the compression braking from the Allison.  I have climbed as well as descended the I-70 grade outside (west) of Denver, the 26 mile drive into Sequoia and been up and down Black Mountain on I-40 near Asheville more times that I can recall.  I also did the 2 mile straight up and down to get in and out of the Denver KOA - West.

it was mid June, 2018 when we did Sequoia.  I was pulling the hills in a higher gear and had to drop back to a lower one to drop the Tranny below 215.  That was the highest that I ever saw.  I called Allison, just to be safe.  The tech said the same thing we had always heard at the Gathering from the Allison expert.  Don’t do over 225 for any extended period….  He said the 20 minutes or so that it was in the 215 range was not an issue.

I can’t add any more….except that if it hits 225….you are flirting with disaster.  That is with the Allison Transynd or the equivalent Mobil….but I won’t use anything but Transynd….  I am on my 2nd change, probably done at 55-57K….the first was around 20K.  I doubt I do another…

EDITED to include one other factoid.  The second oil change had some issues.  I gave my OTR shop the drill and the quantity….and I bought it and also the REAL Allison filter pack.  They let it drain for a while….and it lost more fluid.  Allison said this is common and they recommend not stopping after you open it up and refilling soon thereafter.  I was showing 3 quart low, according to the Allison shifter.  No lights….just my being a worry wart.  I out in a quart….Allison had told me to go ONE a quart….then drive a while….and check again.  It checked OL OK….but I noticed that the downshift was hard….HMMM.  I added another pint or maybe close to a quart.  Still OL OK…  it shifted great.  I did the 8500 mile California to WA and then back to NC, which included the Sequoia climb.  There were a few grades as I climbed to ABQ, but then headed SW as we were going to Reno and Tahoe and on to Sacramento.  I have only put 3 K or so on it since….but it was a little rough the last time out….no issues up and down Black Mountain.  I put in another quart….it was OL OK….before I added, and still OL OK afterwards.  Down shifts like a dream.  No real explanation….except this is my personal experience….

Good luck and keep us posted….

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Posted (edited)

My suggestion was to IR temp the tranny but the teck did that. I would definitely add another cooler before spending $$$ on a new tranny as the temps , while higher than normal, are not that high.

Edited by Ivylog
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On 5/22/2022 at 7:40 AM, flyinghi said:

So yes the tech said he confirmed the high reading with a laser gun from under the coach. (His comment "I have never seen a trans get this hot in my career" -20 years at Allison) They supposedly have the coach up on a lift.  I have thought about an external cooler and have seen some of the posts here, but my regular mechanic poo-pooed the idea, thinking more of the issue was the location of the sensors. Still an external cooler might be the easiest and most cost effective option before replacing the trans. I have never felt the trans slip, lock up or misbehave. I plan to show up tomorrow at the Allison dealer before 2nd shift and talk to a supervisor and the mechanic. 

So you have a working transmission giving you no problems except it is running 'hot'....  I would suggest you quit wasting money on "troubleshooting" and just add an external additional trans cooler like Jim did, and drive on down the road.   Even if that does not "save" this transmission, it will be good for your next one.

I would not replace a transmission for 'running hot' and no other problems!  Why would any mechanic poo-poo adding a cooler??

JMHO

Ken

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59 minutes ago, Chuck B 2004 Windsor said:

IMO, a transmission running hot is due to driver error and habits.

Not in my case, it is due to a smaller oil cooler installed in the rebuilt radiator. 

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