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Technical Trans fluid temp at cooler

Discussion in 'The Hokey Ass Message Board' started by junkyardjeff, Jan 17, 2019.

  1. junkyardjeff
    Joined: Jul 23, 2005
    Posts: 7,531

    junkyardjeff
    Member

    My 55 sunliner never had a fluid cooled trans so when it got the C-4 a cooler was added in front of the radiator,I had trans issues on a trip so I changed to a cooler with more tubes. Sitting in the garage and idling the temp of the fluid was about 15 to 20 degrees cooler coming out and I was wondering if that will be enough,I presume it could be more of a difference going down the road.
     
    chryslerfan55 likes this.
  2. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 8,215

    mgtstumpy
    Member

    Rule of thumb operating range is from 185-250. Cruising at 60mph and the pan temp could be 180 and then you pull a slight grade the temp will go to 200+. Pull a long steep grade or tow and it could climb to 250. If temp climbs to 300 over a prolonged period serious damage could occur. Temp fluctuation is normal however prolonged high temps will definitely shorten the life expectancy of your trans.
    • Good fluid is pink,
    • Red is used; and
    • Brown means you've waited too long.
    For optimum performance change the fluid, purge the system and change the filter every 15k miles (24k klms). For longevity used a quality trans cooler.

    Based on advice, the consensus is to run transmission coolers in a series, from pressure outlet of transmission through radiator first and then through an auxiliary cooler before going back to transmission.

    Firstly, the reasons for this is that if the transmission fluid is hot, it will be cooled more quickly and efficiently by the radiator. Secondly, if it is cool it will be warmed up and yes they can run too cool. When they run cool condensation that may be in the system remains there, NOT GOOD. The transmission needs heat for self preservation but not too much.

    If the fluid is too hot after it leaves the radiator it will be cooled by the auxiliary cooler before going back to the transmission. Auxiliary coolers needs to be mounted where airflow isn't impeded as it needs to dissipate or radiate the heat, air flowing through and over does the job. If stuck for space a small slimline auxiliary coolers with a fan is the go.

    In colder areas and on short trips, the transmission may not get hot enough to reach optimum operating temperature. By being routed through radiator firstly it will be heated to a better temperature.

    I checked my late model in the garage and this is the way the big manufacturers now do it. They spend $M on R&D so why not take advantage of their expertise, it's free. I wouldn't recommend just running an auxiliary cooler, my opinion, but definitely use your radiator. Why, because the transmission generates the second greatest amount of heat beside the engine.

    Another thing, I always use coolant rather than water. It costs a little more however there are a lot more advantages. Water has contaminants that may lead to blockages and corrosion. Coolant also lubricates your water pump. A good radiator also helps.

    I personally prefer to run fluid line through the radiator first and then back through auxiliary transmission cooler. I've seen small air deflectors used to push air over and/or coolers in some instances where space is an issue. Don't have it too low so that you run the risk off loosing it due to road clearance issues. Last thing you want to do is grenade your transmission due to heat buildup and heat will kill them eventually. I've never been a fan of just a stand alone transmission cooler in isolation.
     
    Last edited: Jan 18, 2019
  3. junkyardjeff
    Joined: Jul 23, 2005
    Posts: 7,531

    junkyardjeff
    Member

    All I have is a stand alone cooler on the sunliner,it originally had a air cooled trans and the bottom tank was not strong enough to add a cooler according to the guy who recored the radiator,I like original looking radiators so to get a cooler in the radiator I would have to use a 56 radiator since I think that is when the trans started getting fluid cooled.
     
  4. The engineers designed the automatic transmissions to operate at the same temp as the engine coolant. That's why they use a trans cooler in the radiator. To cold a fluid and clearances never close up to engineered spec. cold fluid will not flow and preform like it should. Having your fluid running colder than the radiator will not make the transmission last any longer. any auxuallary trans cooler should be run in conjunction with the original radiator cooler.55 and 56 fords had a big finned aluminum air cooled Torque convertor. But they also had a radiator cooler also. That radiator cooler wasn't to prevent the trans overheating. It was to warm the fluid up to optimal temp.
     
    Hnstray likes this.

  5. The fords that didn't have trans coolers built into the radiators and had the finned torque converters. they had a remote cooler that had engine coolant piped thru it. connected to the engine with short sections of heater hose and steel pipes. my 56 ford Pickup had one. and a 53 ford car with a flathead auto I worked on had the same setup.
     
    Hnstray likes this.
  6. X-cpe
    Joined: Mar 9, 2018
    Posts: 998

    X-cpe

    I've always heard that, but don't understand it. The only moving part on the liquid side of a cooling system is the water pump impeller and its shaft and the shaft bearings have a seal to keep the coolant off of them. Maybe it is the moving parts of the thermostat or the pressure cap.
     
  7. trollst
    Joined: Jan 27, 2012
    Posts: 1,783

    trollst
    ALLIANCE MEMBER

    Yes, a stand alone cooler is enough, been running my 36 that way 20 years.
     
  8. The older engines sometimes had brass bushings and a external seal that had a packing and a nut you turned to tighten the packing and prevent leakage. those needed some sort of lubricant. Newer pumps have a seal between the impeller and bearing with a weep hole between the seal and bearing. Many times that seal dries out and the water leaks out the weep hole. I make certian its dry and spray some carb cleaner in the weep hole. Then after that exaporated I fill that cavity with RTV silicone. and as long as the bearing is good the water pump is still usable.
     
  9. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    Member
    from Wisconsin

    I've only seen pink transmission fluid a few times and each time it was accompanied by pink coolant as the coil in the radiator leaked and mixed transmission fluid and anti freeze.

    The new fluid I use is red and translucent and gets darker and less translucent as it ages.
     
    egads likes this.
  10. kursplat
    Joined: Apr 22, 2013
    Posts: 290

    kursplat
    ALLIANCE MEMBER

    GM-transmission_failure_chart-365x300.jpg
    every one of these i've seen, all start at 175. maybe they all copy each other, but...?
     
    mgtstumpy likes this.
  11. Not all of them did. I had a '56 coupe with a 292 that had the air-cooled trans and it didn't even have any fittings for an external cooler. When I swapped in a 351W/FMX, I used another radiator I had out of a '56 that had the trans cooler, but it was an aftermarket unit; in fact, I don't recall ever seeing a 'factory' radiator with the cooler installed, all that I saw were aftermarket. I know that the car I pulled the radiator out of had a 'conventional' Fordomatic, not air-cooled.

    Makes me wonder if those weren't warranty 'upgrades' or done when the trans needed rebuilding...
     
  12. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 5,138

    Ebbsspeed
    ALLIANCE MEMBER

    Some water pumps have a spring loaded ceramic faced seal. I assume that a very minute amount of coolant may migrate between the two faces of the seal and provide some lubrication.
     
    Hnstray likes this.
  13. leon bee
    Joined: Mar 15, 2017
    Posts: 519

    leon bee
    Member
    from Arkansas!

    So I guess a transmission temp gauge wouldn't be a waste of effort sometimes.
     
  14. junkyardjeff
    Joined: Jul 23, 2005
    Posts: 7,531

    junkyardjeff
    Member

    I think I am going to look for a 56 radiator so I can have two coolers.
     
  15. LWEL9226
    Joined: Jul 7, 2012
    Posts: 286

    LWEL9226
    Member
    from So. Oregon

    That would be ideal, but don't worry too much if you can't find one, you should be OK with what you have if your cooler is large enough...

    LynnW
     
  16. bdynpnt
    Joined: Feb 9, 2009
    Posts: 354

    bdynpnt
    Member

    56 was still air cooled at least the 3 i have been 57 was water cooled though

    Sent from my SM-G965U using The H.A.M.B. mobile app
     
  17. junkyardjeff
    Joined: Jul 23, 2005
    Posts: 7,531

    junkyardjeff
    Member

    The cooler I am using is a aux cooler from a 90s F150,the first cooler I used only had 4 tubes going through it and the factory cooler has about 20.
     
  18. bdynpnt
    Joined: Feb 9, 2009
    Posts: 354

    bdynpnt
    Member

    It shouldn't run over 200.anytime I used to race an oval track stock car and we had to run gm metric rear with an auto me being a ford guy I ran a 351 w with a c4 and at the end of a 100 lap race on a half-mile oval , running the c4 in second gear .i checked all the temps and the engine, trans and rear axle were all at 200 .thats 50 miles wide open in second gear

    Sent from my SM-G965U using The H.A.M.B. mobile app
     
  19. I would worry about the trans fluid running too cold. Ive had diesel fuel gell in cold weather. Trans fluid could do the same? I always mounted those aftermarket trans coolers on the back side of the radiator so they could be warmed by the radiator. A guy I know simply runs a steel line from the trans to the radiator and makes a loop on the backside of the radiator and attaches it to the core with zip ties. cold thick fluid can build excessive pressure in a auto trans. Back in 77 I was working in western ark. and lived at a Trailer park. and it was freezing and Thawing. Muddy mess. They was a Okie woman that worked at a chicken plant. And it got somuddy I parked my truck on boards to keep the rear wheels from freezing to the ground. This woman has got stuck. so she bought some big 15 inch mud grips to go on the rear of her dodge wagon. It was about 5 degrees and I was looking out the window. She had the battery charger on that old dodge. They had the hood up and her son was spraying starting fluid . and it fired up. She had been messing with it for a long time and I assume was gonna be late for work. So when it finally started she wasn't gonna let it die. She was revving the cold engine to the moon. Her son rapidly unhooked the charger and closed the hood. She dropped it in gear and the front end started to rize. and that torque flight exploded. Looked like someone was murdered that red fluid running over the frozen ground. I went out and fired up my truck and took her to work. Later that day a wrecker came. when he picked up the front there was mud froze to the bottom portion of the tires. and he had trouble taking off and there where large chunks of frozen mud attached to those mud grip tires and the rear wheels weren't rotating. he had to beat the mud off with a sledge hammer.
     
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  20. Gregg Pellicer
    Joined: Aug 20, 2004
    Posts: 1,347

    Gregg Pellicer
    Member

    I'd just install a temp gauge. Preferabliy in the pan. That way you will know for sure whats happening. You might find that your stand alone cooler is enough.
    Gregg
     
  21. junkyardjeff
    Joined: Jul 23, 2005
    Posts: 7,531

    junkyardjeff
    Member

    I had the first cooler up against the radiator and when I removed it there was a bunch of debris between the two so I think the trans was getting a little hot,the new cooler is about a inch from the radiator so this will not happen again.
     

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