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The gauge on the dash for trans temp has a sensor in the bottom outlet of the trans cooler. The trans cooler is an integral part of the radiator on your coach. Open the hatch, look at lower left at bottom of radiator.
Are the temps you are quoting coming from the VDO gauge on the dash, OR a digital signal feeding a VMSPC, Bluefire, or Scangauge?
The digital temp will come from a sensor in the transmission.
The cooler in the space above the rear axle is for hydraulics.
Richard and Rhonda Entrekin
95 Newell, 390 Ex caretaker
99 Newell, 512 Ex caretaker
07 Prevost Marathon, 1025
Maverick Hybrid Toad
Inverness, FL (when we're home

)
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(06-02-2026, 03:31 PM)Richard Wrote: The gauge on the dash for trans temp has a sensor in the bottom outlet of the trans cooler. The trans cooler is an integral part of the radiator on your coach. Open the hatch, look at lower left at bottom of radiator.
Are the temps you are quoting coming from the VDO gauge on the dash, OR a digital signal feeding a VMSPC, Bluefire, or Scangauge?
The digital temp will come from a sensor in the transmission.
The cooler in the space above the rear axle is for hydraulics.
Thanks for clarifying Richard, just have not spent enough time under mine tracing the lines to see what was going to what.
Not to get too far off topic but do you know what controls the fans on the hydraulic cooler? Is it the temp sensor in the hydraulic tank?
I will have to look at mine to see where the transmission cooler lines are running.
Jeff LoGiudice
Temple Terrace, Fl & Loudon & Monterey, TN
1984 Bluebird Wanderlodge PT40
1998 Newell 2000 #490
1986 MCI/TMC 102A3 (sold)
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Jeff , I do NOT know what turns the hyd fans on and off.
Richard and Rhonda Entrekin
95 Newell, 390 Ex caretaker
99 Newell, 512 Ex caretaker
07 Prevost Marathon, 1025
Maverick Hybrid Toad
Inverness, FL (when we're home

)
Posts: 765
Threads: 37
Joined: Jun 2023
(06-02-2026, 04:32 PM)Richard Wrote: Jeff , I do NOT know what turns the hyd fans on and off.
10-4, I will have to go hunting. Just want to make sure they are working.
Jeff LoGiudice
Temple Terrace, Fl & Loudon & Monterey, TN
1984 Bluebird Wanderlodge PT40
1998 Newell 2000 #490
1986 MCI/TMC 102A3 (sold)
Posts: 209
Threads: 12
Joined: May 2017
(06-02-2026, 03:31 PM)Richard Wrote: The gauge on the dash for trans temp has a sensor in the bottom outlet of the trans cooler. The trans cooler is an integral part of the radiator on your coach. Open the hatch, look at lower left at bottom of radiator.
Are the temps you are quoting coming from the VDO gauge on the dash, OR a digital signal feeding a VMSPC, Bluefire, or Scangauge?
The digital temp will come from a sensor in the transmission.
The cooler in the space above the rear axle is for hydraulics.
Hi Richard. Those numbers are coming from the BlueFire.
Dennis White
1997 Newell Coach 454
Canfield OH
Posts: 5,949
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Dennis have you changed filters and replaced fluid with new transynd? If not that would be my first move.
I typically would trust a digital input but since you asked where the sensor was located I might infer you don’t trust the sensor. Easy enough to shoot the upper inlet pipe to the cooler with an IR gun to cross check
Richard and Rhonda Entrekin
95 Newell, 390 Ex caretaker
99 Newell, 512 Ex caretaker
07 Prevost Marathon, 1025
Maverick Hybrid Toad
Inverness, FL (when we're home

)
(This post was last modified: 06-03-2026, 12:41 PM by
Richard.)
Posts: 209
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(06-03-2026, 12:38 PM)Richard Wrote: Dennis have you changed filters and replaced fluid with new transynd? If not that would be my first move.
I typically would trust a digital input but since you asked where the sensor was located I might infer you don’t trust the sensor. Easy enough to shoot the upper inlet pipe to the cooler with an IR gun to cross check
I have not changed the fluid or filters yet. It's on my short list.
Good idea with the IR gun.
I use your bluefire template and it must be "in range" because it doesn't change colors like the water temps does when it gets hot. Unless you didn't do that with the trans temp guage.
Dennis White
1997 Newell Coach 454
Canfield OH
Posts: 5,949
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I don’t think I set up the trans temp to change color. I will look when I get back to the coach.
Richard and Rhonda Entrekin
95 Newell, 390 Ex caretaker
99 Newell, 512 Ex caretaker
07 Prevost Marathon, 1025
Maverick Hybrid Toad
Inverness, FL (when we're home

)
Posts: 528
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(06-04-2026, 05:32 AM)whited44 Wrote: (06-03-2026, 12:38 PM)Richard Wrote: Dennis have you changed filters and replaced fluid with new transynd? If not that would be my first move.
I typically would trust a digital input but since you asked where the sensor was located I might infer you don’t trust the sensor. Easy enough to shoot the upper inlet pipe to the cooler with an IR gun to cross check
I have not changed the fluid or filters yet. It's on my short list.
Recently changed my fluid and filters and dropped 7 degrees.
Brad Aden
1997 Newell #458 - sold
2003 Newell #653 - sold
2007 Prevost Legendary XLII #20
Towing 2020 Grand Cherokee Summit
St. Louis, MO
Posts: 14
Threads: 1
Joined: Jan 2023
Sorry I’m late to the party,
Not a newell owner anymore Prevost H3-45 1998 series 60 b500 trans which is almost identical(maybe less strong) to HD4060 in newell.
I don’t have Jake’s I have a retarder. I was worried sick with my temps and fluid in the beginning.
I run about 200-205 down the road(although I am in Arizona and Mexico) and 225-227(pan) when on big grades.
Also my fluid turned from red to gold color.
Thought I had a trans issues, but I have confirmed from multiple sources(Allison and prevost) these are perfect numbers for my setup and that the red dye burns out of the fluid from heat but does not lose any amount of viscosity or anything from the color change.
So, just watch for abnormalities.
Also both sources said if my pan temps reach 250 start watching like a Hawk
David and Mandy Peterson
Forest almost 5
Elara born in our newell 2 years ago!
1989 DDECII 8v92 coach 209 sold
1997 BMC 40 sold
1998 h3-45 dual slide, dual rooms(one with bunks)
1973 Challenger 50 ketch
(This post was last modified: 06-06-2026, 08:29 AM by
Greasepower.)