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727 Tranny Pan Leaks... How To Stop?

RT6PK

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OK, what is the trick to stopping an automatic tranny pan from leaking? I started with a new chrome steel TCI pan with the supplied rubber gasket. I cleaned off both surfaces with wax and grease remover. I sprayed 3M adhesive on the pan side of the gasket as recommended by several fellow gear heads. I let the adhesive dry per the directions on the can. I cleaned all of the factory bolts and flat washers real good in solvent. I dried everything real good with a clean rag. I tightened the the bolts in a criss-cross pattern like you are supposed to. BUT THE S.O.B. STILL LEAKS. The bolts keep loosening and need re-tightened. Do I need to add lock washers or something?
 
It's probably not the pan. More than likely running down from; band anchor pin, shift shaft or throttle shaft seal, cooler line fittings, nuetral safety switch, dipstick tube O-ring. A stock straight pan will seal with a cork gasket (using no sealer). Pan bolts need to be tightened very lightly (nut driver works well).
Doug
 
Shift shaft or dip stick o ring. 727s are notorious for convertor drain back and flood the pan with fluid when sitting.
 
Use the reusable OEM/Mopar transmission pan gasket. There used on the A-518’s and up.

And as in classic mechanics, make sure bolt holes are clean, no dirt and grit so a proper torque reading can be made when tightening it up.
Both surfaces are clean and flat.
No adhesive!
No seals ya!
Nothing!
Just the gasket.

Transmission fluid is evil. It will find a way out every time through the smallest chink in the armor.
 
727 pan gasket New style plastic with seal
[2464324AC]


buy this and you will never need another one.
 
It's a Mopar, Leaks happen... I thought my pan leaked as well but then noticed the oil pressure line at the back of the block is leaking down.
 
This gasket is for the 904, it is pictured to show what the gasket looks like. Not so much the shape, but texture and the embossed surface.

image.jpg
 
My buddy always said,"It's not a Mopar if it don't leak".
 
I would take the chrome off the seal surface. Grind it, sand it whatever.

Ever scrape gasket sealer off of chrome? Thats right, it doesn’t stick to it. Thats why chrome covers usually leak.
 
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I used the new O-ring style gasket and a new bolt kit with blue Loctite I bought with my aluminum oil pan. My leak stopped. However, there are some who say only use the O-ring gasket on flat flange pans not stock flange pans or they will not seal. I don't have experience to prove that but there are many other threads here and on the interwebs about it.

The O-ring seal is reusable, too.
 
The new gasket works great with the new style 518 pans or pans with no strengthening ribs. Not so well with the older ribbed style pan. Again, the stock gasket will NOT leak if the pan is in good shape and it is not over tightened.
Doug
 
The new gasket works great with the new style 518 pans or pans with no strengthening ribs. Not so well with the older ribbed style pan. Again, the stock gasket will NOT leak if the pan is in good shape and it is not over tightened.
Doug
The 518 pan you mention is ribbed.

s-l1600.jpg
 
The new gasket works great with the new style 518 pans or pans with no strengthening ribs. Not so well with the older ribbed style pan. Again, the stock gasket will NOT leak if the pan is in good shape and it is not over tightened.
Doug
Not in my 2 old style stock OE pan experience. A ‘79 - 904 & a ‘70 - 727. I just 3 weeks ago made the move to the MP deep 727 trans pan and reused the gasket. No issues.
 
Not in my 2 old style stock OE pan experience. A ‘79 - 904 & a ‘70 - 727. I just 3 weeks ago made the move to the MP deep 727 trans pan and reused the gasket. No issues.
I stand corrected.
Doug
 
I've used Mopars transmission pan gasket 2464324AC for years since they came out with it, had my pan off at least 10 times over the years, reused the gasket and it has always reseal the pan with no leaks.
 
I've used Mopars transmission pan 2464324AC for years since they came out with it and had my pan off at least 10 times over the years and reused the gasket and it has always reseal the pan with no leaks.
That's the gasket part number not the pan.
 
OK, what is the trick to stopping an automatic tranny pan from leaking? I started with a new chrome steel TCI pan with the supplied rubber gasket. I cleaned off both surfaces with wax and grease remover. I sprayed 3M adhesive on the pan side of the gasket as recommended by several fellow gear heads. I let the adhesive dry per the directions on the can. I cleaned all of the factory bolts and flat washers real good in solvent. I dried everything real good with a clean rag. I tightened the the bolts in a criss-cross pattern like you are supposed to. BUT THE S.O.B. STILL LEAKS. The bolts keep loosening and need re-tightened. Do I need to add lock washers or something?


I had mine leak for years until I discovered the shift shaft O-ring was the issue
 
Start with thourouly cleaning everything then check often, my bet is these guys are right and it's coming from above. If it is the pan an aftermarket aluminum pan might be a good option. I don't like the stamped steel ones very well because of how flimsy they are, prying a stuck pan can distort them where the aluminum ones are machined flat and are rigid... same goes for valve covers.
 
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