another trans question?need to know what to look for

boggerless · Aug 3, 2005

the truck is a 79 gmc jimmy with a few mods done recently. it has a 350 trans. all was well a few weeks ago when we went off road. last week i went to the store in it and the trans would not shift out of second?when i left the store i shifted manualy and it worked. so i changed the hose on the mod valve and then i couldn't even shift it manually. so i chaged the hose again to no avail.what should i change /check next? i just added a quart of fluid.before it started not working manualy.i thought it being low might be the prob.thanks

big83chevy4x4 · Aug 3, 2005

sounds like the modulator is bad. change that and see if it still does it. you are getting vacuum to the mod right?

diesel4me · Aug 4, 2005

second the modulator..

Yes,I agree,check for vacuum to the modulator,and if there is vacuum,see if any ATF comes out of the nipple on the modulator after you remove it and tip it down toward the ground--if its got fluid in it,its toast,the diaphram is ruptured!...if it feels like it goes into neutral when you let off the gas,its probably modulator related..

A detent cable out of adjustment or sticking can hold the tranny in second gear also..stuck shift valve in the valve body can too.....you did check the fluid to make sure its full,right??.. :crazy:

boggerless · Aug 4, 2005

thanks bro, you and TJ described it to a T.i was kicking my friends asses in the woods then all the sudden i can't make it to the store? :doah:

one has a 85 bronco with a 460 and 38's. the other has a 79 power wagon,3/4 ton with 38's.i scared e'm but all the sudden i have to ride with them. :eek1: