Re: 55 Packard Transmission Cooler Mockup ?

Posted by BH On 2009/12/13 13:02:06

That the factory-installed coolers are failing after 50+ years shows poor design and terrible quality on the part of the manufacturer - NOT!

Seriously, I'm in agreement with Owen and Randy.

I'm not a mechanic by trade, but all other vehicles that I have worked on (or looked up the relevant parts for) and were equipped with a water-cooled engine and automatic transmissions have also had the trans fluid coolers mounted in the coolant stream, but in one of the radiator tanks. Heck, in more recent years, some vehicles even use the other radiator tank for an optional engine oil cooler. Yet, I've seen leaks occur in radiator-mounted coolers in less than 10 years - even in vehicles with plastic tanks. That's why cooling systems should be pressure-checked periodically.

I'm no engineer, but if the coolant entering the water pump inlet is good enough to help cool the engine, why wouldn't it be good enough to cool the trans fluid? As previously noted, no one has provided any empirical evidence, but thanks to Clipper47 for a good tip on assessing the need for an auxiliary cooler. If anything, I'd think that, as positioned on the Packard V8, the trans cooler would get the lowest temperature of all coolant in the total circuit. It's hard to imagine that the coolant would pick up any more heat from the Ultramatic's fluid than from any other tranny with cooler in one of the radiator tanks.

Yet, who can rightfully say that trans fluid coolers that rely upon engine coolant for thermal exchange aren't also intended to help warm up fluid as well? Consider that trans fluid serves a lubricating as well as a hydraulic purpose, and cold, thick fluid doesn't lubricate as well.

Meanwhile, I've only ever seen air-cooled trans fluid coolers installed ahead of the radiator by the factory as an AUXILIARY unit and inline with the radiator-mounted cooler - typically for vehicles intended to tow or carry heavy loads. I'd be surprised if B&M and other suppliers of such coolers didn't recommend retaining the factory-installed unit and using theirs in conjuction with it. That said, I wouldn't be averse to installing an auxiliary cooler for severe usage, whether that be to accomodate for load or ambient temperatures.

Still, after 50+ years, anything of a mechanical nature can fail; it isn't always about miles. Personally, I would want to find out what failed in the stock cooler and repair it.

Are the halves of the Ultramtic cooler tank welded or sweated together? Is the trans fluid passage in the cooler just a piece of steel tubing running in a zig-zag path? If so, one could replace that with something more resistant to corrosion. Many parts stores now offer a corrosions-resistant copper-nickel coated steel tubing that's easy to form - quite popular around here for brake and fuel lines on daily drivers (due to the use of calcium chloride and salt-brine in winter months). While I'm in there, it shouldn't be too difficult to fabricate and install new inlet/outlet coolant pipes for the cooler.

Sounds like it could be a good rebuilding program for one of the established Packard vendors.