mawpd31

wont shift from low to high...any suggestions on where to start looking for problem?

joe_padavano

First, Olds never used a "Powerglide". The two speed trans is a Super Turbine 300 (aka Jetaway), which has nothing in common with a Powerglide other than the fact that it has two speeds. The most likely cause of no upshift is a vacuum modulator that is either not connected or leaking. Verify that the vacuum hose is connected to the modulator and that you have manifold vacuum on the hose. If so, the modulator likely needs to be replaced.

mawpd31

ok thanks I will look at that....is it located at the back of the transmission I think I know where you are talking about

marxjunk

modulator is important on the 2 speed...if fluid is running out of it its bad...its the first thing id look at...

jaunty75

I had a '64 Jetstar 88 back in the '90s, and it had the 2-speed Jetaway. The vacuum modulator developed a hole in the diaphragm, and what gave it away more than difficulty upshifting (which I did notice, although it didn't seem severe as I recall) was gobs of white smoke coming out of the tailpipe when I would accelerate. Turned out that transmission fluid was being drawn through the hole in the diaphragm and right into the engine, where it was being burned up. Replacing the modulator fixed the problem.

Any chance you're seeing white smoke, maybe even just a little bit, from the exhaust?

jaunty75

Yes. On the right side towards the rear of the transmission. Here's a relevant figure out of the '68 chassis service manual. You DO have a '68 Olds Chassis Service Manual, don't you?

The modulator is the canister-looking thing the Modulator Pipe attaches to in the lower left of the figure.