w123 shifting w/o vacuum
 

Simple as that, will a w123 AT shift without vacuum?

SIL's 85 300D has an intermittent issue where the car apparently will not shift from a gear. The only option is to go to the side of the road, wait, then start up again and it will go.

Im thinking clogged filter or low fluid, but the car seemingly has had some vac issues.

Thoughts?

Thanks!

I have the vac line unplugged from the modulator on my TD.... sure it will shift. It's shifts hard enough to make me yell bad words. One day I will fix the problem.

I'm not sure that is such a good idea. Wouldn't that put extra stress onto the flex discs causing a premature failure?

I agree it's not a good idea. I have a long list of repairs for all my car's. The massive vac problems of the TD is somewhere on that list. Right now the '87 300d on jack stands in my garage for 3 weeks take the top of the list :eek:

supossedly hard shifts= longer transmission life. Idk about REALLY hard shifting though

My SD doesn't have any vacuum and, yeah, hard shifts. I agree with turbobenz, that will help with transmission longevity and the more stress on the flex discs will be from park, I don't keep my foot on the brake pedal. I figure to replace discs is easier, cheaper too, than to open the transmission.

I haven't had vacuum to my transmission for about 6 months since my modulator failed ('81 TD). Yea, it shifts hard, especially the downshifts, but I don't worry about it too much since hard shifts are actually easier on the bands. Of course, it is hard on the drivetrain, but I have learned to put it in neutral for the 3 to 2 and 2 to 1 downshifts until it warms up. Once warmed up, they are just crisp.

I am waiting for the time to replace the modulator and the K1 spring. I'll probably adjust to crisper shifts, since my tranny has 260k and I want to extend its life as long as I can.

Lack of upshifts is not usually a symptom of a vacuum problem. It is typically a symptom of either a stuck bowden cable or a stuck kickdown switch.