2000 Mustang Transmission Plug with O-ring Keeps Leaking ATF

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  #1  
Old 08-09-16, 10:42 AM
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2000 Mustang Transmission Plug with O-ring Keeps Leaking ATF

Hi,

I have this headache over the leaking O-ring on the bottom of my 2000 Mustang V6 transmission. Any help will be very much appreciated.

Older Mustangs used to have the speedometer cable attached to the bottom of the transmission. Then Ford, in its wisdom, decided to move that cable to the engine. Rather than re-designing the transmission to eliminate the hole left by the relocation of the speedometer cable attachment, they opted for a plug with an O-ring that fits on a baby finger to plug that hole.

The original O-ring lasted 13 years on my Mustang. Then it started leaking. I had my trusted mechanic replace the O-ring with one that he had sitting around in his shop of the right size. That fix lasted two years and the leak started up again. I assumed that it was an issue with the material composition of the O-ring and its lack of compatibility with the Ford Mercon V automatic transmission fluid the vehicle uses. So I went to my local dealer, and paid about $5.00 for a pair of tiny O-rings worth about 50 cents, believing that the new O-rings were the proper ones and would last over ten years each. I went back to my mechanic and had him replace the leaky O-ring with a brand new one from the Ford Dealership. The old one did look disintegrated on close inspection.

One year later and the leak is right back. So much for the compatibility between the dealer supplied O-ring and the Mercon V ATF !!!

Given that the location of this plug is right in the middle of the undercarriage of the car, the car must be up on a hoist for access, so I cannot do this on jack stands, and I have to pay a minimum charge every time that these dumb a$$ rings fail. It is becoming a real headache.

Does anyone know where to get an O-ring that will last like the original, with true compatibility with that Mercon V synthetic fluid?

I have contacted Ford of Canada who advised me to contact a couple of places in the USA, who then told me they buy obsolete parts from Ford and sell them. The Ford rep also told me that Ford has no technical personnel to help with this issue!!! BUT, they do want to sell me another car !!!

Any ideas will be greatly appreciated.

quickcurrent
 
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  #2  
Old 08-09-16, 04:35 PM
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Can that hole be tapped and simply bolted shut? Personally, I'd have epoxied something into it to keep it shut forever.
 
  #3  
Old 08-09-16, 09:03 PM
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Found an interesting site that sells the complete plug.
Steeda Transmission Speedometer Plug for Ford Mustang 1999-2004

I'm wondering if a copper washer could also be used. Like found on the oil pan drain plug.

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Old 08-12-16, 07:33 AM
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Thanks, guys. Somebody also suggested welding it shut. I am not sure that one can weld the bottom of the transmission case with the ATF there with regard to flammability and the fluid there keeping the metal from heating properly to allow the welding to take place, even if little fluid comes out when the plug is removed.

The copper ring/washer has promise, it most likely would not decompose with the ATF fluid, but where to find something that fits properly? The complete plug still uses an O-ring, so probably no different.

ukrbyk, tapped and bolted shut? I's love to do that, but how? Epoxy likely would not cure since the hole cannot be dry from the fluid unless the transmission is taken right out and drained completely or turned upside down. Even during a transmission fluid change only about 1 gallon of the fluid comes out and there are over three gallons of that stuff in the transmission!
 
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Old 08-12-16, 07:37 AM
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Somebody has also suggested some silicone sealant applied to the O-ring. Don't know if that would hold up, but it would be a simple solution!
 
  #6  
Old 08-12-16, 08:16 AM
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I doubt silicone would offer any help. The area/threads would have to be 100% oil free.

My local auto parts store has a bin of the copper washers in many sizes.
Not sure if the big guys carry them. I guess you'd find them on those HELP cards.
 
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