727 Leak

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Zak

Zak

FABO Gold Member
FABO Gold Member
Joined
Jun 3, 2010
Messages
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Location
Valdosta, Georgia
Cannot stop a leak from pan. Verified zero seep from shift linkage...dipstick...top of trans. Swapped gasket twice with high quality gaskets. Sealed one side and then both sides of gaskets. Will not leak during operation..only when static. Pan is new chrome from Summit. Torques specs always utilized. Using Fram synthetic ATF+4 fluid. At wits end. I read an article advising not to use synthetic and go back to Mopar regular trans fluid. Any truth to that? Any other inputs?
 
I had one leaking, changed pan gasket twice. Found connector on neutral safety switch full of fluid coming thru one of the switch pins. Changed switch to a standard motor products. Leaked again thru the electrical pins. Bought NOS Mopar leak is gone. Thought for sure it was the pan.
 
Well, what about the leak isnt the pan?? There are numerous areas where seepage is possible, that will always end up running around the pan gasket area, such as, rear band anchor pin, shifter shaft/kickdown, safety switch, etc. Also, bear in mind that case porosity is known cause of leakage since these came out in the early 60's. Fluid is fluid....makes no diff which one in this case, unless youve got it foaming out the top of the case.
 

727 transmission are like HD motor cycles if they have fluids in them they leak a drop here or there. Sitting long time equals a leak Worry when they stop.
 
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As mentioned by 340 6 get the pan gasket you want is the one used from the factory on the A518 series of transmission. In the industry we used to call them the Zero leak gasket.
 
transman said:
As mentioned by 340 6 get the pan gasket you want is the one used from the factory on the A518 series of transmission. In the industry we used to call them the Zero leak gasket.
Click to expand...
They are not cheap but do work and are reusable
I know in most cases cars like ours sit. And just getting them out and used (hot) seals up small drips too.
 
I had similar issues with my dad’s 727. It was from sitting and the converter drain back which caused the leak. I sealed the pan studs with aviation sealant and it took care of it. However there are other possibilities which others have outlined in this thread. The front few holes for pan studs/bolts see fluid. Sealing my dads with aviation worked. This little rectangle hole in front of the pump allows the front few studs/bolts to see fluid after the converter drains back after sitting.

IMG_4398.jpeg
 
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