Skip to main content ↑ ↓
Topic: Transmission cooling (Read 516 times) previous topic - next topic

Transmission cooling

Being a new owner (ISM), I'm in need of some schooling.  This has to do with the transmission overheating described in my earlier subject: "Bought the Coach", but I felt this needed to be a separate discussion.  I've identified the coolant radiator as being the outboard cooler.  There is a smaller "radiator" sandwiched between the radiator and another large one (presumably the tranny cooler) and then there is a cylinder (6"x22") just inboard of that that has large dia. hoses attached to the transmission.  In my previous experience, the large cooler with fins, attached to the radiator was the transmission cooler and I am assuming that this is also the case.  What is the cylinder and how does it relate to the cooler with fins?  To be able to discuss this, I need to get the nomenclature right.
Thanks for any help.
2000 U320 mid entry  #5688
2006 Jeep Liberty


USMCR retired
SDFD retired
FEMA US&R TF8

Re: Transmission cooling

Reply #1 –
The cylinder is your trans cooler. The smaller one is a fuel cooler. Someone with your model can better identify yours On mine outboard is fuel cooler then air cooler the one next to the fans is my radiator.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Transmission cooling

Reply #2 –
Howdy Sven, 
    As Craneman indicated, the cylinder is transmission cooler.  From outside in towards engine its, fuel cooler, CAC, the engine coolant radiator.  I'll attach a photo with grill removed, the small radiator is fuel cooler, the large radiator is CAC, then inboard not in picture is coolant radiator.
  Love your coach, a mid-entry is a real unicorn in the unicoach world.
Dave A
Dave and Nancy Abel
'00 U320 36' WTFE  Build #5669
'10 Jeep Wrangler Unlimited Rubicon
Livingston, TX  SKP's Fulltiming

Re: Transmission cooling

Reply #3 –
Quote from: Dave and Nancy Abel –
Howdy Sven, 
    As Craneman indicated, the cylinder is transmission cooler.  From outside in towards engine its, fuel cooler, CAC, the engine coolant radiator.  I'll attach a photo with grill removed, the small radiator is fuel cooler, the large radiator is CAC, then inboard not in picture is coolant radiator.
  Love your coach, a mid-entry is a real unicorn in the unicoach world.
Dave A

 Add hydraulic cooler between CAC and Radiator.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Transmission cooling

Reply #4 –

Quote from: craneman –
Add hydraulic cooler between CAC and Radiator.
Thanks craneman, completely overlooked the hydraulic cooler.
Dave A
Dave and Nancy Abel
'00 U320 36' WTFE  Build #5669
'10 Jeep Wrangler Unlimited Rubicon
Livingston, TX  SKP's Fulltiming

Re: Transmission cooling

Reply #5 –
I learned from an Allison service manager, that the transmission computer will shut off the retarder if it gets too hot to protect the transmission.  He pointed to a lot full of city vehicles, most he said with retarders.  He went on to say, they are never here for  transmission issues.
Dave Cobb
Buckhorn Lake Resort The Club, #6202, Kerrville TX
check the map.  I do rent it out when I am traveling!
2001, U320, 36' #5887, in Kerrville, FT Club #17006, (7/23 to present)
2024 Jeep Grand Cherokee L, Summit, white
EX: 98 U295, 36' #5219, (mid door), (4/13-10/23)
EX: 93 U225, 36' (4/11 to 4/13)

Re: Transmission cooling

Reply #6 –
Too many dang coolers to keep up with, but the fog is starting to lift.  From the photo, I understand that the large "radiator" that we can see from the street is the CAC (charged air cooler) which cools the intake manifold air.  The cylinder is a heat exchanger through which passes coolant and ATF, with a metal tube separating them.  The fans are attached to the coolant radiator, which looks like the transmission coolers I've seen in the past. 
Has anyone used Loctite Extend for dealing with surface rust?
Thanks again for the effort in educating me.
2000 U320 mid entry  #5688
2006 Jeep Liberty


USMCR retired
SDFD retired
FEMA US&R TF8