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Questions and Answers

Ford Explorer Transmission Seal

Q. Good Day Vince, I have a 1991 Ford Explorer and I have a concern about a pretty bad leak coming from the front of my automatic transmission. I was having a problem with the transmission shifting right and from your column I read that it was most likely that the fluid and filter needed changing.

Well I changed the fluid and filter and I found that the fluid was burnt pretty bad. After the change I took the vehicle for a test drive and the transmission shifted normally. What has me concerned is that it started leaking fluid from the front of the transmission, like it was coming from the front seal.

Could this have happened because the old fluid was so bad and when replaced it caused an increase in pressure that caused the old seal to fail? I would really appreciate your help in this as I do not want to drop the transmission and replace the seal if it will be a waste of time.

1991 Explorer XLT
4.0 liter

Thank You,

A. Sometimes if the transmission has a lot of miles on it and no regular transmission services, then it is more likely a transmission fluid and filter change will do more harm than good.

In the case of a seal, the gunk and garbage collect inside the seal and push it up against the shaft keeping a good seal. When you put in new fluid this gunk gets cleaned out and if the seal is bad enough, it starts to leak.

Now if you have the A4LD transmission in there, there is a possibility that even if you replace the seal, it will start leaking again in a short time. From TSB #012 dated June 1990 Front Seal Blowout

If you have repeated front seal blowouts on A4LD's, it may not be a problem with the seal or the quality of your work. You could have a bad bell housing. The bushing used in the A4LD is finished in place. Because of this the bore that the bushing fits into doesn't need to be in the center of the bell housing, and in many cases it isn't. When you're working on an A4LD you need to check the bell housing bushing to see if it's the original factory bushing. If it is, and it's not worn (no more than .003" converter hub to bushing clearance) DON'T REPLACE IT!

If the bushing needs to be replaced you need to make sure the replacement bushing will fit in the center of the bell housing. To do this bolt the torque converter to the flex plate. Turn the engine over and check the run out of the converter hub. Now bolt the bell housing to the engine. If the Torque converter is contacting one side of the bushing (see figure below), the bushing is off center and the bell housing MUST be replaced. By checking the bell housing first you can avoid repeated front seal blowout.

I would have a Ford dealer do this and a reminder of this bulletin and TSB: 87-43 Front Bushing Wear.

Added 12/16/02...

Omega Machine & Tools Inc. has a cheaper repair alternative to replacing the complete bell housing. They can replace the bushing, line bore it and install a new seal. Contact info@omegamachine.com or call 1-800-601-7722 for complete information.

Additional Information provided courtesy of AllDATA

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© 2003 Vincent T. Ciulla

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