Lance Andrus Posted October 10, 2010 Share Posted October 10, 2010 I could really use some advice here. My tranny always seems to run fairly hot. I replaced the radiator last year and have installed the largest cooler I can find in my local parts stores. I also installed a capillary tube tranny gauge last year and replaced the filter and fluid while I had the pan off.. Coming home today the gauge was reading about 240 for the majority of the trip. My question, what could be causing that poor tranny to be running so hot. The motor seems to run fairly cool as the engine temp gauge never reaches the mid way point in it's travel. As I understand it, with the fluid running through the radiator and then through a separate cooler, the temp shouldn't get above 190. I have a fairly long trip coming up next month and I really don't feel very safe with the tranny running that hot. What is going wrong???? Quote Link to comment Share on other sites More sharing options...
WME Posted October 11, 2010 Share Posted October 11, 2010 Where is the gauge sender mounted?? Quote Link to comment Share on other sites More sharing options...
Lance Andrus Posted October 13, 2010 Author Share Posted October 13, 2010 In the bottom front corner of the pan. I installed it following some directions I found on the board. Where is the gauge sender mounted?? Quote Link to comment Share on other sites More sharing options...
WME Posted October 13, 2010 Share Posted October 13, 2010 The fluid should be much cooler than that there. Dumb questions first are you sure that you have the coolers inline and haven't just accidentally bypassed them?? You can buy a small IR temp reader, get one and make sure that the gauge is correct. I run my fluids through the extra cooler first and then the built in cooler. Winter driving here in Wyoming. I block off the extra cooler and help keep the fluid warm from the radiator. I'm not talking cold, but dammn cold like -20 degrees. Quote Link to comment Share on other sites More sharing options...
Lance Andrus Posted October 15, 2010 Author Share Posted October 15, 2010 When I replaced the radiator I reinstalled the inlet line and then ran the out side into the extra cooler. the ran the extra cooler out line back to the tranny. Not sure how I could have bypassed them but I'll check them this weekend. The fluid should be much cooler than that there. Dumb questions first are you sure that you have the coolers inline and haven't just accidentally bypassed them?? You can buy a small IR temp reader, get one and make sure that the gauge is correct. I run my fluids through the extra cooler first and then the built in cooler. Winter driving here in Wyoming. I block off the extra cooler and help keep the fluid warm from the radiator. I'm not talking cold, but dammn cold like -20 degrees. Quote Link to comment Share on other sites More sharing options...
wetboy Posted October 17, 2010 Share Posted October 17, 2010 When I replaced the radiator I reinstalled the inlet line and then ran the out side into the extra cooler. the ran the extra cooler out line back to the tranny. Not sure how I could have bypassed them but I'll check them this weekend. You have the same setup and routing that I have. My tranny runs plenty cool. First thing I would suspect is a faulty gauge, assuming you're just doing normal Toy RV driving and not trying to cruise at 80 all day. Make sure the sender wiring is not running alongside some very hot part of the engine. Also, your tranny cooler is in front of the radiator just behind the grill, right? I have seen some setups with terrible airflow, so I have to ask. Other than that, pull your tranny cooler return line and make sure you got good flow. There could be an obstruction or hose kink. The first hose I tried had a sharp bend, so I had to put on a longer one with a gentler bend radius. I'll be interested in see what you find. Quote Link to comment Share on other sites More sharing options...
Gulfstream Greg Posted October 25, 2010 Share Posted October 25, 2010 The fluid that travels to the cooler is just a small amount tapped out of the system then returned to the system. Things that cause high temps are slipping bands, slipping torque converter, on and off the gas on windy roads. As an experiment you could disconnect the cooler line and have some one start it up and make sure you actually have oil flowing through the cooling circuit. Its not really high pressure but there should be some good flow. I have no idea what line is supply or return. When we had the Sunrader I saw temps as high as 240. It had a locking torque converter. As a note only the 6 cyl and turbo 4 cyl have locking torque converters. The non-turbo 4 cyl does not have a locking torque converter and as a result will see higher temps than the 6 cyl. Personally I would not trust the capillary temp type gauge. Sounds though like this is a recent temp problem. What temp did it used to run at. Something may have clogged your cooling circuit. Not sure if 190 degrees is right. Maybe sometimes zipping down the freeway. On a curvy road or climbing a long grade I would expect to see it much higher. I might be wrong. Do you have a 4 or 6 cyl. Quote Link to comment Share on other sites More sharing options...
Lance Andrus Posted November 1, 2010 Author Share Posted November 1, 2010 The fluid that travels to the cooler is just a small amount tapped out of the system then returned to the system. Things that cause high temps are slipping bands, slipping torque converter, on and off the gas on windy roads. As an experiment you could disconnect the cooler line and have some one start it up and make sure you actually have oil flowing through the cooling circuit. Its not really high pressure but there should be some good flow. I have no idea what line is supply or return. When we had the Sunrader I saw temps as high as 240. It had a locking torque converter. As a note only the 6 cyl and turbo 4 cyl have locking torque converters. The non-turbo 4 cyl does not have a locking torque converter and as a result will see higher temps than the 6 cyl. Personally I would not trust the capillary temp type gauge. Sounds though like this is a recent temp problem. What temp did it used to run at. Something may have clogged your cooling circuit. Not sure if 190 degrees is right. Maybe sometimes zipping down the freeway. On a curvy road or climbing a long grade I would expect to see it much higher. I might be wrong. Do you have a 4 or 6 cyl. UPDATE: Pulled the return line yesterday...not sure if the flow is good or not....seemed to have a fair amount of air in the system. When the pump picked up oil it pumped it strong. However, my coach is parked on a fairly good down slope....will pull it level this afternoon and try it again. Fluid is very brown so I'm fairly sure the fluid is getting hotter than it should. Started coach and let it warm up while monitoring temp in the cooler...Cooler remained cool until the engine thermostat opened and then the cooler temp shot up...I'm assuming this is normal. Coach normally runs cool and before I installed the gauge, not sure how hot the tranny was running.....2 years ago I took it into the mountains...strange thing...when I was running straight out on the interstate, it ran hotter than in the mountains.......3 weeks ago I noticed that when I backed off the gas, the temp goes down....sounds like I may have a tranny issue and not a cooling system issue. 4 cyl Quote Link to comment Share on other sites More sharing options...
Gulfstream Greg Posted November 9, 2010 Share Posted November 9, 2010 I don't know much about how torque converters are built and operate but I suppose they could start to fail and slip more. I think you need to make a few calls to shops that have experience with those transmissions. Quote Link to comment Share on other sites More sharing options...
Maineah Posted November 10, 2010 Share Posted November 10, 2010 Yes when the thermo opened the radiator actual heated the trans fluid, normal. You are likely to see higher temps at highway speeds then climbing hills one reason being that the trans most likely down shifted lowering the gear ratio making it easier on the converter. Highway speeds with the huge wind drag the MH has will make the converter slip all converters slip unless they are in lockup that is where your heat is. No matter how big a cooler you install the trans will run close to engine temp it is after all bolted to it and part of the cooler is being cooled by the engine coolant. If your fluid is discolored it probably is time to flush it but be advised if it has high mileage and has never been done you are probably better off leaving it alone. If you decide to flush it (the only way you will ever get it all changed) replenish the fluid with a synthetic fluid it will stand much higher temps. Quote Link to comment Share on other sites More sharing options...
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