7.3 IDI leaking transmission fluid into motor oil

gandalf

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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.


I agree, there is no crossover point. Nowhere does the transmission fluid go through any part of the engine. It's possible for the transmission fluid to get into the coolant, in the radiator, but if that in turn leaks into the engine it would show as coolant rather than transmission fluid. Other than that, if transmission fluid is leaking, it must be hitting the ground. If the oil level is rising, I'd look for coolant in the oil.

There is only one possibility for a direct transfer. It must be osmosis. ;p
 

Agnem

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Well this is why I was asking, because in my view in order for this to happen, we are looking at a most bizarre and rare possibility. The first thing I would do, is send a crankcase sample off to Blackstone, specifically telling them to look for either transmission fluid, or diesel fuel.

Crankcase oil levels can rise due to a leaking fuel pump, or a bad IP. Transmission fluid levels can drop due to a seal puke or other external leak.

My bet is you have two different things going on, that look like they are related. Science will determine!
 

wrgallant

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The reason that I'm pretty sure that it is transmission fluid is that it only happens when an external cooler is used. If I plug the transmission feeds to the external cooler, the problem stops.
 

riotwarrior

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The reason that I'm pretty sure that it is transmission fluid is that it only happens when an external cooler is used. If I plug the transmission feeds to the external cooler, the problem stops.
How about some pictures?
Trace the external cooler lines.....do they pass into or out of the stock trans cooler in the rad tank?

You have four physically separate systems here..

Cooling...

Engine Oil

Trans....

Fuel...

Now cooling and engine oil can mix due to leaks in the oil cooler on Left side of the engine...usually leaks OIL into coolant...raising the oil level dropping the coolant level

Fuel can leak into the engine oil due to the diaphram in the fuel pump rupturing ...thus raising engine oil level again

Transmission fluid can leak into the coolant if the stock trans cooler in the lower radiator tank is ruptured...thus oil into coolant again...

So the only way trans fluid could get into engine oil is beyond me since the pressure differential between the coolant and engine oil and trans fluid systems prevents this...

engine oil is higher pressure than coolant
trans oil is higher than coolant

It appears to me you have issues that need professional diagnosing...

as mentioned take oil sample and send off to blackstone!
 

trackspeeder

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The reason that I'm pretty sure that it is transmission fluid is that it only happens when an external cooler is used. If I plug the transmission feeds to the external cooler, the problem stops.

If you hav a leak in the O/A cooler it will be very visible. Fluid leakage on or around the cooler will be present.
This type cooler can not leak into the engine. It has no connections to the engine, just the tranny.
 

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