Thursday, December 26, 2013

Some 'Splainin'

An oldie, but a goodie
Indeed, the rebuild has begun. The case has been mostly emptied, and soon it will be time to start the tedious process of taking apart, cleaning, and putting back together every section you see out on the table down below. After my glorious Festivus victory at Ye Olde Battle of Torque Converter, everything came out pretty much like the book said it would, so that was a relief. Some things were reluctant to move, since bolt threads can get pretty set in their ways after a few decades, but a little WD-40, as usual, provided the necessary persuasion.
this is a weird, bird's eye, wide-angle shot, but you get the idea.

This is the first time the transmission has been opened up since it failed, and I’m pleased to be able to provide a definitive diagnosis, as follows, for all the symptoms that have been observed, both by Worth and myself. 

The transmission started out its failure with a screeching sound when in operation, which turned out to be its death throes. It then failed entirely, and did not respond at all when the shifter was moved into gear – it was like the transmission and wheels were unaware of the presence of the running engine.

Oddly enough, I had a dream, before I even got the transmission out, that the problem was in the torque converter, and that a new one would cost $91. Why? Who knows. But, strange to tell, that’s almost exactly what a replacement will cost, and even if I hadn’t chosen to cut it apart, it would have needed replacement anyway. Alert readers will remember my long struggle to remove the converter, which was royally stuck in place. The root issue was as described by a user in yet another forum I visited…

“…it looks like they overheated the Torque Converter. What happened then is that the fluid in the converter became really hot and caused the inner pump gear to grow and seize. The converter hub is either distorted and wrapped around the step on the ground sleeve and/or is distorted enough that it won't pull out through the bushing. It will take 2000-4000 lbs to pull it out. You'll need a really solid bar and some jack screws. The pump, torque converter, and most likely the ground sleeve are ruined.”

Once I got the torque converter and pump out, I could see that the hub on the end of the torque converter that connects to the pump just behind it, had indeed warped. It got deformed so badly that two large pieces broke off of it (photo 1 below), and the rest curled back and hooked around the bushing (photo 2 below), making the torque converter impossible to remove. 

that piece of metal in my hand, and another like it, used to help drive the pump, and likely snapped off when the pump gear overheated and seized.

slightly below center, the warped and jagged thing around the shaft
The torque converter could still spin freely with the engine, but the pump - the transmission’s heart - was now not being turned. This means that there was no fluid pressure or circulation, which I observed in another entry a while back. When these things are lacking, then you are having a bad problem and you will not go to space today.

Symptoms: screeching, then an eerie silence and immobility.

Diagnosis: no transmission fluid pressure, due to a terminal overheating failure of the pump gear and converter hub, which in turn was likely due to a fluid leak.

Treatment: new torque converter and pump, as part of a complete rebuild.

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