Packard Forum Index » V-8 (1955-56)

Hi Jed, just curious to hear what your finding were, especially since Dave and Ross give excellent testimony for the coolers heat exchanger element durability. Also curious about the chocolate emulsion, as pointed out, trans. fluid would likely be more red.

Let us know what you find.

Well, I took it to my local shop and they pulled the tranny cooler and pressure tested it. They found a hole on the inside of the cooler allowing the tranny fluid to get into the coolant system. I'm not sure why the coolant didn't get into the transmission but the fluid there was nice and clear.

The fix was to plug the holes for the transmission lines at the cooler and install an aftermarket transmission cooler in front of the radiator. I've alsways wanted to do this anyway so this was motivation to do it.

Actually, Max Merrit listed a stock replacement for $225 so I figured why pay the money for a stock cooler when I can put a new one on for less $$ and never have to worry about this problem again.

I had them flush the cooling system and drove her home last night. Seems to run great and so far the coolant is clear! Well, clear green. I'm not sure but maybe green + red does = brown. Actually, the coolant was a sickly tan color, almost like melted chocolat ice cream.

Considering the other problems this could have been, like a blown head gasket or cracked block, I feel blessed that it was an easily correctable problem. Thanks to everyone for their help in diagnosing this issue.

Jed

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Yes, red+green does = brown.

Jed wrote: Quote:

The stock Packard trans cooler has been the subject of discussion before. When I first bought my 55 Pat, I thought that cooler was an tranny leak waiting to happen. So, one of the first mods I made to my Pat was to remove it and replace it with a modern air cooler mounted in front of the rad. I even found a standard lower rad hose that would replace the two couplers and the cooler (Goodyear #60706).

Just another example of a "mod" that prevents future headaches, if you are interested in that kind of thing.

Craig

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A good question. Can understand why the trans fluid would go into the coolant as the "converter out" pressure can be 30-50 psi which even after an orifice and pressure drop would still be a fairly decent "cooler in" pressure. Even in direct drive when the converter is along for the ride, it never drops below 10 according to the charts.

What is interesting is that when the engine was stopped and coolant pressure was higher than fluid pressure it didn't force it's way back to trans. That return route just dumps into the pan. My guess would be maybe the hole acted like a flap and inner pressure forced it open but pressure from coolant forced it back to mostly closed. Another guess would be that you might have relieved the coolant pressure before it had time.

At any rate, glad it was fairly simple, there was no damage and you found and corrected it in time.

Hmm? draining the trans and refilling it seems like cheap insurance. Just pondering the problem. How did the stainless steel develop a hole??

I think this has been discussed somewhere but has anyone taken one apart to see if those flat inner plates are actually stainless steel? I've always thought even with the coolant crud on them, when scratched they looked more like brass.

Thank you for sharing the diagnosis Jed. My curiosity was peeked and I wondered what you found. I am sorry it was indeed a defective heat exchanger, but glad it was not something more involved or less easily corrected.

Happy motoring,
Jim