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Author Topic: Transmission temperature rising with age  (Read 626 times)

Al Lewis

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Transmission temperature rising with age
« on: July 11, 2018, 12:03:58 AM »
First an update in case you have followed previous posts. In recent months I have changed a rear ride height control valve and both rear air springs. I took a little trip and all seems to be well with the suspension.

Over the years my transmission temperature has been rising. An 02 model Allison with 85000 miles. With ambient temperature 90 degrees or more and a couple stoplights without shifting to neutral the temperature Will get to 230 degrees. Years ago it rarely went above 190. I have switched to synthetic oil with no help. Then I did a pretty good job cleaning radiator and cooler fins. Again no help. I have the Cummins engine with rear radiator and transmission cooler to the rear of the big radiator.

Anyone else experience this and what is the next step to cool this thing down?
2002 Monterey, Cumins ISC 350, Texas

Mike Shumack

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Re: Transmission temperature rising with age
« Reply #1 on: July 11, 2018, 12:23:03 AM »
What are you reading the temp with - Aladdin or dash gauge or something else? The dash gauges  are known to become inaccurate over time. When I got my coach the dash trans temp gauge was about 50 degrees off.
« Last Edit: July 11, 2018, 11:35:09 AM by Mike Shumack »
- Mike

'05 Beaver Patriot Thunder 42ft, Vicksburg, CAT C13  525HP, Allison 4000MH

David T. Richelderfer

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Re: Transmission temperature rising with age
« Reply #2 on: July 11, 2018, 02:06:59 AM »
Our coach has just the opposite problem - too cool.  We know a fellow Beaver owner who knew the previous owner of our coach and he told me our coach's transmission used to overheat so that prior owner had an auxiliary transmission cooler/radiator installed.  The highest transmission temperature we have seen in six years of ownership has been about 140F... and that when the outside temperature was 100+F.  Our transmission runs about 40 to 45F over outside temperatures.  In winters the transmission still runs about 40 to 45F over the outside temperatures.  At those times we don't see 100F temperatures very often for the transmission.  Our coach has about 75,000 miles.
« Last Edit: July 11, 2018, 02:23:56 AM by David T. Richelderfer »
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George Harwell

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Re: Transmission temperature rising with age
« Reply #3 on: July 11, 2018, 01:07:25 PM »
Al, what are your engine temperature readings? It can be hard to cool the tranny if the engine is running hot. You can reduce the transmission temperature by dropping from 6th gear to 5th gear and even 4th if necessary to keep the unit from overheating. I have the 350 CUMMINS with rear radiator that runs 180 degrees except when driving mountains in the summertime. The transmission runs about the same as the engine except in the mountains where I downshift and reduce the power to 90% for a comfortable climb.
U
« Last Edit: July 11, 2018, 06:55:48 PM by George Harwell »
03 Beaver Monterey
800495
350 Cummins

Al Lewis

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Re: Transmission temperature rising with age
« Reply #4 on: July 11, 2018, 08:59:35 PM »
I am reading the factory installed dash gauge. That is all I have. I wonder where the sensor is. Maybe I could change it.

I had previously had a problem with The oil pressure sensor leaking and giving a low reading.

The engine temperature has always ran 180 degrees.
2002 Monterey, Cumins ISC 350, Texas

Mike Shumack

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Re: Transmission temperature rising with age
« Reply #5 on: July 11, 2018, 09:33:32 PM »
I changed my trans temp sensor. It's located in the hose coming off transmission going to cooler.

This is the sensor (my '05 Patriot w/ Allision 4000 uses) https://www.amazon.com/gp/product/B005BIAXU8/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
- Mike

'05 Beaver Patriot Thunder 42ft, Vicksburg, CAT C13  525HP, Allison 4000MH

Jerry Emert

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Re: Transmission temperature rising with age
« Reply #6 on: July 12, 2018, 01:58:34 AM »
My 4000 keeps getting hotter as the day goes by.  Just before 250 I'll downshift to 5th.  It cools pretty fast.  I can also stop at a rest area for 5 minutes and the temp will go down 25 degrees.  When I asked Allison about it they said that the 4000 routinely runs as hot as 350 in dump trucks.  I was very worried after seeing all the posts here about temps running about the same as engine.  My engine may get to 192 climbing, I did see 194 yesterday climbing.  I've just accepted it and gotten used to it.
Jerry, Chief USN Retired
2003 Patriot Thunder Lexington 40' 3 Slides
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Mike Shumack

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Re: Transmission temperature rising with age
« Reply #7 on: July 12, 2018, 11:01:23 AM »
The Allison Operator's Manual says "the transmission is considered overheated when the Sump fluid temp exceeds 250 degrees F or the Fluid to Cooler exceeds 300 degrees F. If the sump temp reaches 262 degrees, the ECU will inhibit operation in the higher ranges."

If overheating, operator should pull over put trans in neutral and run the engine rpm between 1200 and 1500 for a couple of minutes.
- Mike

'05 Beaver Patriot Thunder 42ft, Vicksburg, CAT C13  525HP, Allison 4000MH

George Harwell

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Re: Transmission temperature rising with age
« Reply #8 on: July 12, 2018, 12:08:02 PM »
Al, as mentioned earlier the dash gauges aren’t very reliable. I replaced the sensor and gauge on my coach and it still reads 30 to 40 degrees low. Since I have the Aladdin monitor I gave up using the gauge. The sensor is mounted on the front of the transmission where the hoses are attached.
03 Beaver Monterey
800495
350 Cummins

Jerry Emert

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Re: Transmission temperature rising with age
« Reply #9 on: July 12, 2018, 01:54:41 PM »
When I first noticed the issue I compared the gauge, Aladdin and took a temp reading with a hand held temp gun.  They all agreed so I'm sure mine is hot.  Hope your is easier.
Jerry
Jerry, Chief USN Retired
2003 Patriot Thunder Lexington 40' 3 Slides
C-12 Ser#  2KS89983
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Mike Shumack

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Re: Transmission temperature rising with age
« Reply #10 on: July 12, 2018, 02:41:00 PM »
Jerry, do you have one of these "standalone" transmission coolers? I've read that there are some problems with this style (leaking o-rings I think). There was a redesign available if that was the problem, but maybe it is clogged. If not clogged, then it could have been undersized from Beaver.
Just keep an eye on the temps and pull over when necessary and let things cool down.
Good luck
- Mike

'05 Beaver Patriot Thunder 42ft, Vicksburg, CAT C13  525HP, Allison 4000MH
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Jerry Emert

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Re: Transmission temperature rising with age
« Reply #11 on: July 12, 2018, 03:26:24 PM »
Thanks.  I don't know enough about it to tell for sure.  From comments earlier this does look like what was described.  I also took it to Stewart and Stevenson a couple years ago in Grand Junction to have it checked out.  They could find anything wrong and they wern't worried about my temps.  I still downshift to 5th when it gets close to 250.  Even a short stop at a traffic light will drop temp by 10 degrees or so.  Drives nice as far as I can tell.  I guess I'll see! Thanks.
Jerry
Jerry, Chief USN Retired
2003 Patriot Thunder Lexington 40' 3 Slides
C-12 Ser#  2KS89983
4000MH

Larry Dedrick

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Re: Transmission temperature rising with age
« Reply #12 on: July 16, 2018, 05:07:40 PM »
Al
         What everyone has mentioned sounds reasonable. I believe, if as you say, "over the years" the transmission temp has gradually increased, my thoughts would be, possibly, sediment building up around your transmission cooler, IF and i mean If the cooler is within your engines radiator and positioned internally in the bottom of the radiator, sediment could be contributing to your progressive rise in temperature over the years.
          I would consider having the engine radiator flushed to make sure that is not the culprit. It used to be routine in the automobile industry years back to flush radiators.
           Just wanted to give you my ideas, if nothing else is working.

            Larry Dedrick
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Bill Sprague

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Re: Transmission temperature rising with age
« Reply #13 on: July 16, 2018, 05:18:44 PM »
My worry was contamination.   On some Beavers there are some fittings where dissimilar metal corrosion will allow coolant to leak into the transmission fluid.  A first indicator can be rising transmission temperatures.  If it happens, the remedy is a new transmission and new radiator! 

As one who worries a lot, I got on a program with Blackstone Labs for both engine oil and transmission fluid analysis.   
Bill Sprague
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Al Lewis

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Re: Transmission temperature rising with age
« Reply #14 on: July 18, 2018, 04:32:49 PM »
My cooler is not in the engine radiator just mounted behind it. I found the sensor thanks to the help here. The electrical connection was Oily and dirty from minor leaks. Assuming the sensor is a thermister and low
Resistance means hot, my theory is there is electrical leakage to ground giving a false higher gauge reading. I did a crude test in the shop today cleaning the connection with carb cleaner. I think the gauge reading dropped a little but I don't have high confidence.  it will be october before I have a road trip. If I still think it helped I will give it a better cleaning next summer. Maybe a silicone coating would protect the next 15 years!
2002 Monterey, Cumins ISC 350, Texas