7.3 IDI leaking transmission fluid into motor oil

wrgallant

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I have a 94 7.3 idi turbo that leaks transmission fluid into the motor when the transmission cooler is connected. I plugged the transmission ports that feed the cooler and the leaking stopped. My guess is that the cooler is causing some sort of pressure difference that is forcing the fluid into the motor.
 

OLDBULL8

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There shouldn't be any connection between the engine and transmission. Are you talking about an auxilliary transmission cooler mounted in front of the radiator? You do have an automatic trans, right?
 

Agnem

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Where is this "leaked" transmission fluid showing up? In the motor oil, or the coolant. If in the motor oil, how do you know that this is happening?
 

riotwarrior

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Sounds like a leak in a rad tank cooler to me! Getting trans fluid into the coolant and contaminating the coolant, caused by pressure differential of trans pressure and coolant pressure

maybe wrong...

JM2CW
 

trackspeeder

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Sounds like a leak in a rad tank cooler to me! Getting trans fluid into the coolant and contaminating the coolant, caused by pressure differential of trans pressure and coolant pressure

maybe wrong...

JM2CW

X2 Coolers can fail with age. A good radiator shop can fix it.
 

wrgallant

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Transmission fluid is showing up in motor oil - I can tell because motor oil level goes up and trans fluid level goes down.
 

wrgallant

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I get transmission fluid in the motor oil with an auxiliary cooler with no fluid passing through the radiator.
 

OLDBULL8

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There is no way for transmission oil to get into the engine crankcase oil, in a normal engine, transmission hooked together.
Surely, no one would hook the transmission cooler return line into the engine.That would be the only way it could get there.
 

wrgallant

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Would an external cooler lower fluid pressure in the transmission? I had the transmission off to replace the flex plate over the winter. Could I have damaged a seal?
 

justinray

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Could you damage the seal? Yes, but a damaged seal would leak oil out, not tranny fluid in, fluid always goes from a high pressure area to a low pressure area, the crankcase isn't necessarily what I would call a vacuum.
 

wrgallant

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Could the cooler cause the transmission fluid pressure to be higher than the crankcase pressure?
 
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