Alright fellas...decided to start a fresh thread so things wouldn't get jumbled up in the other one. Here's the run down:


Last week the C6 in the Bronco started shifting extremely erraticly and sluggishly. And the hotter the ambient temp got and the hotter the tranny temp got, the worse the tranny got. I also noticed signs of a bad vacuum leak. The signs pointed to a bad vacuum modulator. I pulled the line to the modulator and had tranny fluid basicly all the way to the intake tree.


So I replaced the modulator. Vacuum issues went away. The 1-2 shift is perfect again. The 2-3 shift and WOT downshift is perfect again...until the tranny starts warming up, but the 1-2 shift remains perfect. Here again the hotter the outside air, the quicker the problem starts happening...and the warmer the tranny gets the worse the problem gets. And by 'problem', I mean letting off the gas to allow it to shift sometimes and other times it has a really sluggish shift. But when it's cool, the first 15-30 minutes everything is perfect.


I also noticed the 2-3 shift is happening a little later even when cold and I attribute that to the new modulator. I pulled a purple band modulator, so I replaced it with a purple band modulator. (My books stated a purple or black band would suffice)


The fluid level is correct. The fluid looks great and was completely replaced about 3 months ago. I didn't notice any kinking in the exposed tranny cooler lines, and it appeared I had good flow from the cooler outlet.


Any thoughts or suggestions? I would have thought if my tranny was going bad, it would be bad at all times and not just when it warms up. Any and all help is greatly appreciated.

Well you already checked the extent of what I would be able to tell you. I vaguely remember you asking if a kinked line you had before would cause any problems and in here you say you don't see any kinks. Did you repair that line the last time? I may have missed that thread. Other than what was covered in the other thread I have no other suggestions since I never took one apart and I'm no expert in diagnosing transmission problems. This is the one reason I prefer manual. Seems easier to diagnose.

Yeah Sean...I did in fact kink the last 3-4" of the cooler inlet line. But since it was a low pressure line, I cut the damaged length, then I just grabbed a nipple, some hose and a couple hose clamps. Makes me wonder if I didn't tighten down the hose clamps a little too tight and collapse the line or the nipple when I threw things together last time. Thanks for the reminder Sean.

Couldn't hurt to check that. Those brass fittings are fairly soft. The rubber hose is fine for repair though.

I'm no expert either,

But Knowing what I know of hydraulics (see I can even spell it) poor performance upon heating is an indication of internal leakage. The only auto trans I ever rebuilt was in a Dogde (intentional mis spell). Then I winched the truck up on a trailer and paid a guy 1100 to redo my work. Poorly sealed valve body and somptin called a sprag unit. Where or how to diagnose your problem is above my pay grade.

^^^Well that's not very reassuring. Couldn't you have told me everything is cupcakes and cotton candy...and all I'd have to do is click my heels three times and it would have fixed it.

I did stay at the Holiday Inn Express. But a long time ago. I really cant help much was only relaying my experience. Its like Clint said, "A mans gotta know his limitations"