I’m hoping some of our wrench-turning Dopers can give me a hand here.
I’m going to look at a '85 Chevy K30, 6.2L diesel, 4x4, Automatic tonight for use a plowtruck/ farm truck.
The guy that owns it says there is a problem with the transmission, when accelerating the truck does not want to shift into 2nd gear. He says you really have to wind it up and then take your foot off the gas to get it to shift, after that it will shift normally to 3rd and up. But then the next time you slow down to 1st gear again you have to go through the whole process again.
My completely unprofessional and ridiculously hopeful thought is that it may just need a new filter. I had similar, but not as dramatic, shifting issues with a Land Rover I used to own and a new filter cleared them right up.
Can you tell me what the more expensive and extensive causes of this problem might be? thanks for any help.
If it was a gas engine I would say the vacuum modulator is bad. But diesels don’t have one of those. (No manifold vacuum).
So off the top of my gin soaked head:
Low fluid level
Kick down cable mal adjusted (assuming that this trans has one)
Gunk in the valve body
Sticking valve body valve.
Maybe Gary T will stop by. I think he knows a bunch move knows a bunch more about auto trans boxes.
Thanks Rick, I ended up buying the truck so whatever the problem is, I own it now. To tell the truth, I really didn’t notice that much of a problem when test driving it, but I will check out the valve body anyway.
I believe it is the TH400, I had no idea that they would attach a mechanical vacuum pump! I will look for that as well. And thanks for the acetone tip. I won’t have the truck in my possession until Wednesday so I’ll report back what I find.