Auxiliary Tranmission Oil Cooler - In the bid to save the trannie.
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04-01-2010, 11:06 PM
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Auxiliary Tranmission Oil Cooler - In the bid to save the trannie.
Caravan, Anniversary Edition 2004, 3.3L :
I just had my transmission up and running smooth. Fixed a few issues, but I thought it wise to look into installing an auxiliary transmission cooler. So from an auto engineer one receives this opinion below (which causes me great confusion as to whether one should install one of these coolers. Please note that I will not be towing, just normal/average city driving.
"Auxiliary transmission oil coolers were popular and often a must when auto transmissions didn't have lock-up torque converters. The oil got hot, more so when towing, due to the slippage in the torque converter. Not fitting an additional oil could and often did result in expensive tranmission failures.
These days all autos have torque converters that lock up at some stage of the operation, usually above a certain engine speed. In a lock up situation there is no slippage and the oil in the auto trans will not get any hotter than the engine oil. The up and down shift patterns are controlled by a management computer which has, as one its inputs, the transmission oil temperature. This can mean that a transmission may not change up into a particular higher gear until the oil has reached a particular temperature. Often the trans will not shift into top until this temperature has been reached. Fitting a trans oil cooler,in addition to the standard one, can upset the trans operation
Thes days the rules are quite simple. If the manufacturer does not recommend the fitment of a trans cooler you accept their recommendation. Reasons usually are that the cooler(s) already fitted are deemed adequate.
If you want to monitor the transmission oil temperature by all means invest in a gauge that can keep track of temperature changes. However most vehicles have a built-in safety system that will prevent the vehicle being driven under conditions that are likely to cause excessively high transmission oil temperatures.
If you want to be kind to the car it would help if you can learn to determine when the torque converter unlocks. This usually occurs when the load on the engine increases above a pre-determined point. By monitoring the rev counter, it should be possible to note an increase in engine revs without an increase in road speed. When that occurs it is generally an indication that a lower gear should be used.
I personally find it hard to believe that a car manufacturer would suggest something that is not in the best interest of the long term reliability of the vehicle. Yes, there was a time where you would unreservedly say to fit an auxiliary transmission oil cooler. But times change. I have discussed this issue with many auto trans specialists. Some will quickly say to fit one, just to be safe. This is often based on experiences with older transmissions. But when questioned as to how many late model transmissions they have repaired where the damage was definitely caused by not fitting an additional cooler when one wasn't recommended, the hard evidence is a bit hard to find ."
I just had my transmission up and running smooth. Fixed a few issues, but I thought it wise to look into installing an auxiliary transmission cooler. So from an auto engineer one receives this opinion below (which causes me great confusion as to whether one should install one of these coolers. Please note that I will not be towing, just normal/average city driving.
"Auxiliary transmission oil coolers were popular and often a must when auto transmissions didn't have lock-up torque converters. The oil got hot, more so when towing, due to the slippage in the torque converter. Not fitting an additional oil could and often did result in expensive tranmission failures.
These days all autos have torque converters that lock up at some stage of the operation, usually above a certain engine speed. In a lock up situation there is no slippage and the oil in the auto trans will not get any hotter than the engine oil. The up and down shift patterns are controlled by a management computer which has, as one its inputs, the transmission oil temperature. This can mean that a transmission may not change up into a particular higher gear until the oil has reached a particular temperature. Often the trans will not shift into top until this temperature has been reached. Fitting a trans oil cooler,in addition to the standard one, can upset the trans operation
Thes days the rules are quite simple. If the manufacturer does not recommend the fitment of a trans cooler you accept their recommendation. Reasons usually are that the cooler(s) already fitted are deemed adequate.
If you want to monitor the transmission oil temperature by all means invest in a gauge that can keep track of temperature changes. However most vehicles have a built-in safety system that will prevent the vehicle being driven under conditions that are likely to cause excessively high transmission oil temperatures.
If you want to be kind to the car it would help if you can learn to determine when the torque converter unlocks. This usually occurs when the load on the engine increases above a pre-determined point. By monitoring the rev counter, it should be possible to note an increase in engine revs without an increase in road speed. When that occurs it is generally an indication that a lower gear should be used.
I personally find it hard to believe that a car manufacturer would suggest something that is not in the best interest of the long term reliability of the vehicle. Yes, there was a time where you would unreservedly say to fit an auxiliary transmission oil cooler. But times change. I have discussed this issue with many auto trans specialists. Some will quickly say to fit one, just to be safe. This is often based on experiences with older transmissions. But when questioned as to how many late model transmissions they have repaired where the damage was definitely caused by not fitting an additional cooler when one wasn't recommended, the hard evidence is a bit hard to find ."
