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Discussion Starter · #1 ·
Around 6 months ago, my truck's tranny began leaking a small amount of ATF. It has slowly gotten worse and I've now probably lost between 4-8 ounces of fluid (just a guess, but the fluid level is still in the middle of the safe zone and it isn't overheating at all). What is bizarre is it leaks worse when I fire it up for a very short period of time and don't get the trans warm (i.e. just moving it around in the driveway, where the two largest leaks I've encountered happened). When the trans is hot, it will still put a few drops on the driveway but it's not nearly as much.

I removed the inspection plate and inside the bellhousing looks good - all dry and it doesn't look like the TC is leaking. The whole trans case was so oily I sprayed some engine degreaser on it and power-washed it to try to identify the leak more closely, and was able to confirm it is not leaking at the commonly failed shifter shaft seal. From what I can tell, it looks to be leaking fairly high up on the case, somewhere above where the starter mounts. It's coming down the driver side of the bellhousing so I don't think it's related to the heat exchanger. Any ideas?

The trans is due for a service, but I was hoping to get this issue sorted out beforehand so I don't put in fresh ATF to only have to drain it again.
 

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Is it seeping from the vent tube?
 

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That location sounds like a cooler pipe or the heat exchanger on the side of the block, so long as you are sure it is trani fluid and not oil or PS.
 

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Discussion Starter · #4 ·

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Comes right off the top closer to the rear of the trans.
 

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Discussion Starter · #6 ·
Comes right off the top closer to the rear of the trans.
Ok thanks. I think it's leaking too far forward on the trans for that to be it but I'll check that spot too
 

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Discussion Starter · #7 ·
That location sounds like a cooler pipe or the heat exchanger on the side of the block, so long as you are sure it is trani fluid and not oil or PS.
It's coming down the opposite side of the heat exchanger so I don't think that's the issue. Cooler line could be possible. I purchased PDD's trans cooler line kit and will be installing that once I narrow down the issue.

The other one I learned that apparently can commonly fail is the dipstick o-ring. Given where the fluid is beginning to drip, high and at the front, this location makes some sense.
 

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A mirror and flashlight are your friend.
 
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Transmission dipstick is on the passenger side.

With the little amount your pics show, it could be a coolant line which runs ahead of the starter and road wind is blowing it up there. If your power steering has ATF in it, it could be from there or associated hoses also.
 
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