TH350 shift problem

Joel · February 24, 2002

My 74 1/2 ton chevy hit another problem, it won't shift properly. It will wind up to 4,500 RPM+ before shifting into second. If you let off the gas or quite accelerating it will stay in first.

What could be causing this problem? Vaccum module?

Joel

Import Hater · February 24, 2002

I think you're on the right track looking at the vacuum modulator.

Rob

Joel · February 24, 2002

Today its fine. I guess the problem was just that one time. Should the module be replaced anyway?

Joel

jjgmc · March 18, 2002

I have 87 k10 does the same thing holds first gear up 3500-4000 rpm it was rebuilt 5 months ago don't know why any thoughts have not had the time to fix it.

badpewterz · March 19, 2002

i would also make sure the vacum line going to to modulator is in good shape, not pinced or melted or rotted in the metal section

Joel · March 27, 2002

I called a trusty trans shop that has been around since the 70's about the affects of a bad modulator. He said my problems could be from that part and also said what 01badgmc did. If there is no vacuum, it will have the same problem

So after work I check out the vacuum line and sure enough it was pinched .

I fixed the line and went for a drive. Problem solved! GOD that made my day, didn't spend a dime and fixed a huge problem.

Joel