Derek up North Posted December 6, 2015 Share Posted December 6, 2015 Like I said, opinions will always vary. But I'd stop short of referring to most of them as 'ridiculous'. Without installing 2 temperature gauges, I won't GUESS if the pan oil is hotter than the oil exiting the transmission going to the cooler. Quote Link to comment Share on other sites More sharing options...
zero Posted December 6, 2015 Share Posted December 6, 2015 The fluid going to the cooler is not necessarily the hottest. According to GM, Ford, and Toyota - oil going to the cooler is hotter then in the sump when the trans is hot. Not necessarily when the trans is cooler then the engine coolant;. Makes sense to me. Makes little sense to NOT send the hottest oil to the cooler when necessary. Of course there is issue of oil running too cold also. The trans oil tube in the radiator (when used is also a heater). Ford had service bulletins out on the diesel F250s and F350s about the transmissions running too cool at times when aux. coolers were used and were installing thermostatic bypass valves as a fix. I suspect now with all the microprocessor controls everywhere - trans oil is only cooled when needed - but that is only a guess. I have not studied any of the newest transmissions. I'm not sure what exactly you are calling "ridiculous." I guess I'm not even sure what you are calling a "transmission." When I refer to the transmission - I mean the trans and torque-converter as a unit. The trans itself hardly makes any heat unless you shift it a couple of hundred times an hour. It is the torque-converter that makes the major heat. The hottest oil in the whole mess is the oil leaving the torque-converter. On most auto transmissions - that oil is sent to the cooler when leaving the converter. I know on my 88 Toyota - just a quick check with a laser thermometer shows the oil-pan on the trans to often be 20 degrees cooler then the oil in the line going to the cooler. Since my concern is the max heat my oil gets to (since anything near the Flash Point will destroy the oil's lube ability) - I've got my temp-sender in that line going to the cooler. The simple flow diagram is just a generic one but pretty much applies to most automatic transmissions I know of. Quote Link to comment Share on other sites More sharing options...
jjrbus Posted December 6, 2015 Share Posted December 6, 2015 I have seen many charts on transmission fluid and how temperature affects lifespan. Where are they measuring the temperature at? Is this done in some Sci Fi looking lab with all kinds of high tech equipment or is this Joe and Fred at the corner transmission shop making it up as they go along? Quote Link to comment Share on other sites More sharing options...
Derek up North Posted December 6, 2015 Share Posted December 6, 2015 That chart and other similar and pretty coloured ones are floating all over the internet and all seem to originate from people trying to sell transmission coolers. No details of any test procedure, of course. If anyone can provide a source of independently conducted test, I'd like to read them. Well, maybe not read, but skim over them. Quote Link to comment Share on other sites More sharing options...
jjrbus Posted December 6, 2015 Share Posted December 6, 2015 Do the modern computerized cars monitor transmission fluid temp's? Quote Link to comment Share on other sites More sharing options...
zero Posted December 6, 2015 Share Posted December 6, 2015 They must. Even 1980s transmissions have temp sensors inside the control body. With the transmissions though - all they do (as I recall) is prevent converter lock-up if too hot. I have no idea what controls are on the newest transmissions. In ref. to heat and transmission life? I doubt any blanket statement of temp covers all transmissions. Much depends on the age of the trans and materials inside. But certain things are going to hold true to all. #1 - Standard automatic transmission oil has a Flash Point of around 375 degrees F. That means the oil loses all ability to lube anything at 375F and all transmissions run that hot will fail. #2 - the Nitrile used in many seals in older transmissions often has a max operating range of around 250 degrees F. Anything above and the seals deteriorate much more quickly. Newer seals made from materials like Fluorine can run in temps up to 400 degrees F. #3 - all transmissions I have worked with other then a few old cast-iron GM Powerglides are aluminum with steel shafts, drums, and gears. There are temp extremes that must be adhered to - just to keep the parts clearances within range due to expansion and contraction. With most specs I've read - 300 degrees F is the safe limit. Quote Link to comment Share on other sites More sharing options...
a2ndopinion Posted December 7, 2015 Share Posted December 7, 2015 Do the modern computerized cars monitor transmission fluid temp's? Most of them do, causing codes ranging from P0710 through P0714, all temp sensor codes, including low input and high input. Quote Link to comment Share on other sites More sharing options...
jjrbus Posted December 7, 2015 Share Posted December 7, 2015 Out of curiosity I poked around a bit and the sensors seem to be various places in the transmission, impracticable for most of us to add one there. It seems the best place for DIY'er to add a sensor would be in the line leaving the transmission going to the cooler. I believe we would be looking for anomaly's in temperature not precise reading's? Quote Link to comment Share on other sites More sharing options...
a2ndopinion Posted December 7, 2015 Share Posted December 7, 2015 I don't know how to relate this, but we had a similar discussion on celica-gts.com about where to put the electric fan t-stat. The initial feeling was to sense the temp of the fluid leaving the engine (at the t-stat housing or along the upper rad hose), as if it is too hot, it'd turn the fan on. After pages of discussion, the conclusion was made that it makes more sense to have it at the lower hose, to turn the fan(s) on if the cooled liquid leaving the rad was still too hot. And yes, I agree with looking for anomalies, but also for excess rise, like when pulling a hill. My dad, with his 30 some foot 454 powered coach would watch for his magical 210 degree point, when he'd ease off the accelerator and drop the TH400 to 2nd and enjoy the view. Quote Link to comment Share on other sites More sharing options...
Derek up North Posted December 7, 2015 Share Posted December 7, 2015 I believe we would be looking for anomalies in temperature not precise readings? Basically what I said about 5 pages ago. Quote Link to comment Share on other sites More sharing options...
jjrbus Posted December 7, 2015 Share Posted December 7, 2015 Basically what I said about 5 pages ago. You really don't expect me to remember do you? Jim Quote Link to comment Share on other sites More sharing options...
Derek up North Posted December 7, 2015 Share Posted December 7, 2015 Nope. Just another way of agreeing with you. Quote Link to comment Share on other sites More sharing options...
redskinman Posted March 26, 2017 Share Posted March 26, 2017 On 8/6/2015 at 5:26 AM, linda s said: Absolutely agree that the newer ones all came with an external trannie cooler. Definitely all the V6 models Linda S So where is transmission cooler on V-6? It's very early in the morning here or I would go outside and look again,but when I've looked before I did not see one.Maybe I;m just overlooking it,but I did not see one where I would think one would be{mounted in front of the radiator} Quote Link to comment Share on other sites More sharing options...
redskinman Posted March 26, 2017 Share Posted March 26, 2017 Ok it's gotten daylight and now that I've concentrated on finding it pretty sure this is it located in front of the radiator. Quote Link to comment Share on other sites More sharing options...
jjrbus Posted March 26, 2017 Share Posted March 26, 2017 That looks like it, on my 93 V6 it is in front of the AC condenser on the passenger side, looks like a small radiator. Hard to see or photograph. Did anyone add a temp sensor? I picked up one of these and was going to use epoxy to attach it to the transmission pan, but like so many other things have not got around to it, maybe in the next life. $6 on Amazon Quote Link to comment Share on other sites More sharing options...
redskinman Posted March 26, 2017 Share Posted March 26, 2017 6 minutes ago, jjrbus said: That looks like it, on my 93 V6 it is in front of the AC condenser on the passenger side, looks like a small radiator. Hard to see or photograph. Did anyone add a temp sensor? I picked up one of these and was going to use epoxy to attach it to the transmission pan, but like so many other things have not got around to it, maybe in the next life. $6 on Amazon Yeah thats about where mine is located,yes it's hard to get into that spot and photograph it Quote Link to comment Share on other sites More sharing options...
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