I didn't know my tranny could smell so bad

I had recently changed the transmission fluid in my pickup truck and had enough fluid to complete another job.  I decided to use this remaining fluid to refresh the fluid in the 280z.  After taking the car for a quick drive, I parked it on the lift to begin the change.

The first step in changing the fluid is NOT to drain the fluid.  The first step is changing the fluid is to make sure you can remove the fill plug!  It would be bad to be able to drain but not fill.  In my case, the fill plug was easy to remove.

The drain plug, however, was a different matter entirely.  Using a 24" breaker bar, I could not budge the plug.  

My last resort was to break out the propane torch and heat the surrounding metal, but I decided to first give PB Blaster a shot at it.  I sprayed the PB Blaster on the exposed plug threads and let is soak in.  Then again... and again.  After ten minutes, I tried again to remove the plug.  No go.  I ended up taking a break and returning an hour or so later to give it one more shot.  Success!  I removed the plug and let the fluid drain into the catch pan.  Then it hit me... a horrible smell.  That transmission fluid was RANK!  It was a deep black color as well.

I think this oil is past its useful life.  I allowed the fluid to drain for hours.  In the meantime, I checked for leaks and found fluid coming from the speedometer pickup.  I decided not to let this opportunity pass by; since I had the transmission drained I'd swap the seals on the speedometer pickup as well.

Another order to ZCarDepot and a few days later, I received the seals.  To replace these seals, the speedometer pickup must be removed.  This is easily accomplished by removing the retainer held in place by the 10mm bolt just below.

The unit is not threaded in place, so just rotate it back and forth while pulling to remove it from the transmission.  Be prepared for more fluid to expel when this comes out.  In my case I prepared by holding my nose.  Once the pickup is out, clean it up.

 

Next, pull the roll pin that holds the pinion gear and shaft in place.  In my case the roll pin was exposed enough to grab it with a pair of pliers and pull it out.

The outer seal was a piece of cake; it is just an o-ring.  Pop it out, clean the groove, run some grease in the groove, and put the new o-ring in.  The inner seal, however, proved to be much more difficult.  This seal is tucked away neatly and tightly, very tightly.  I used a dental pick to pull on the seal, but it didn't move.  I became committed though when the pick tore the old seal.  I then heated the body (without the outer seal in place) in an attempt to loosen the bond.  I ended up bending one of the picks into a hook and really pulling hard to get the old seal out.

After cleaning the old gunk and grease out of the housing and putting a layer of new grease inside, the new seal pressed right into place.  Be sure that the "open" side of the seal faces the inside of the transmission.  Reassembly is the reverse of disassembly.  Be sure to coat the outside of the pickup body and outer seal with grease before replacing.  After sliding the pickup back into place, return the retainer and bolt, then reattach the speedometer cable.

Now that the speedometer pickup was back into place, I could refill the transmission.  For this task I used a Penzoil fluid pump which is an invaluable tool for filling transmissions and differentials where the plug is impossible to reach with a funnel.

I am excited to feel the difference in shifting with the new synthetic fluid in place!