Re: 55/56 QUESTION

Posted by Owen_Dyneto On 2014/4/27 22:11:50

Stewart- I don't think it's a good idea to think that Packard engineers selected a liquid/liquid heat exchanger (it's both a heater and cooler) for the transmission oil rather than a simple air/liquid cooler without forethought of the conditions that would be encountered. You might think about the following two possibilities:

1. Assume you are stuck on an extremely hot day in traffic that just crawls at 5 mph or less for an hour or more. You're in torque converter so you'll be generating huge amounts of heat but you'll have no airflow over your cooler other than what the fan might draw at an idle speed or close to it and thus little or no cooling of the fluid. With the factory unit you'd still be cooling to whatever the coolant temperature happened to be. If the situation lasts long enough (and it did to me), bye-bye transmission friction surfaces.

2. Let's say with your air-only cooler you'll be driving at reasonable road speeds on a cold day. The temperature with the wind chill factor at the cooler could easily get to below 0 F.; on a very cold day even 20 or 30 degrees below 0, and the fluid will never warm to operating temperatures, pressures will be very high, liquid flow will be reduced and lubrication will be sacrificed.

The factory cooler is very efficient and also due to internal construction of the core in stainless steel, failures are almost unheard of. If you must install an air cooler forward of the radiator, put in in series with (and before) the factory unit. In that manner in extremely hot conditions it will remove some heat and decrease the amount of work the factory cooler will have to do. And in very cold weather it may take the fluid to extremely low temperatures but the factory unit may still be able to warm the fluid sufficiently to avoid problems.