Not a good situation. Don't drive it! The transmission cooler that is built in to the radiator is bad. The radiator needs to be replaced and the cooling system and transmission needs to be flushed completely. If any coolant is mixed with the transmission fluid it will destroy the transmission in a very short time. I repeat, don't drive it, have it towed to your local garage for repair.
Transmission fluid mixed with washing powder
Check coolant in radiator could be getting mixed with transmission fluid due to a bad radiator cooling chamber Check the modulator could be getting burned as fuel Check for leak
When you changed the Radiator did you flush the engine to remove the transmission fluid that the already mixed with your water in the engine block. If not that would explain the presence of the fluid in the coolant holding tank.
I can't see any reason for water to get in the transmission unless it went under water from a flood or crossing a stream. If engine coolant is getting into the transmission I would blame the transmission oil cooler in the radiator in which case the radiator would need replacement and the transmission flushed professionally. If the vehicle was driven with coolant mixed in with the transmission fluid you will probably have transmission failure before long.
Coolant from radiator? Run engine to normal operating temperature -remove transmission dipstick and let a drop fall on hot part of engine, oil will "smoke" coolant will "sizzle" If so a bad radiator allow transmission fluid from cooler lines to get mixed with engine coolant
The transmission oil cooler is located inside the radiator. If the transmission oil cooler developes a leak the oil will mix with the engine coolant. Check the transmission fluid. If it looks like a strawberry milk shake the transmission is in trouble. The longer you drive it the more it will cost to fix. Have it towed to a transmission shop asap.
Automatic transmission fluid is often circulated through a small section of a car's radiator to keep it cool. Getting coolant mixed with your ATF would mean there is a problem with your radiator. Remove the radiator from the car and get it into a radiator shop for repair. Don't drive the car because you'll risk permanently damaging your transmission. A radiator repair should be fairly inexpensive, even if you have to have parts de-soldered from the core and replaced. Even a new replacement radiator is relatively inexpensive if you R&R it yourself. Have fun.
The trans fluid will take on a pink, milky look.
The transmission oil cooler inside the radiator is bad. DO NOT RUN THE ENGINE OR DRIVE IT ANY FURTHER! Have it towed to a trans shop for repair and a flush then hope for the best.
Your transmission cooler tank (its inside of your radiator) has gotting a leak in it. Your tranny fluid & antifreeze are being mixed with each other. You need to have your radiator fix & a complete flush of both the tranny and radiator. If your transmission has not slipped any you will be ok as long as you don't wait about having it fixed. The longer you wait about having it fix the more damage it can do to your tranny. Your hub that holds your tranny clutches (the band) has a glued sand paper like material on it that the water will harm if trere to long.
Mercron transmission fluid is used in a 1978 Ford Thunderbird. Type F fluid can also be used but should not be mixed.
Radiator is sectioned off--one section for antifreeze engine coolant the other is a chamber for transmission fluid to circulate and cooled. The chamber in your has ruptured allowing fluids to mix. You may as well considered the transmission to be "cooked" by now antifreeze has infilterated transmission and torque converter.