C4 tranny hurtin

[chuzie]

It is not the vac. I would suspect the governor shuttle valve is stuck or less likely, a valve body issue. This prevents it from shifting all the way down to first and leaves you sort of in between 1st and 2nd until you give it enough power to force it to shift into first. This will eventually eat up the transmission if you allow it to continue. I suggest you keep shifting manually.

You can pull the transfer case off and observe the governor on the output shaft of the transmission. You can remove the bolts (2 or 4 i believe) and slide it off. You will see a large metal valve on one side. It should move freely under spring pressure.

This is usually caused by some sort of contamination in your system that the filter did not catch which leads me to wonder if this is secondary to a more pressing deterioration in the system like clutch or band material.

I would suggest you pull the pan and inspect the condition of the fluid and check for debris both in the pan and the filter. Also observe the smell and color of the fluid; should be red and not smell burnt. If that "pans" out pull the governor and have a shop take a look at it. They can clean it up and lap the valve for under $20.

How many miles since your last rebuild and last fluid change?