Van - Chevrolet - Transmissions :: Fluid Leaking / Car Won't Drive Forward

I have recently run into a problem with my transmission on my van, mainly that it won't drive forward, however reverse seems to work just fine. Prior to the problem: Before it stopped working altogether, there were a few symptoms that I should tell you before we get started. First, upon starting the vehicle and putting it into drive the vehicle acted like it was in neutral, or barely crawled forwarded. If you waited a few moments, or pressed the accelerator, it would quickly engage and once it had been driven for 5 minutes no more problems shifting gears would occur.

I attributed these problems to low fluid and/or cold fluid (as the problem would noticeably become better/worse with warmer/colder conditions respectively) So I was content with topping off the fluid and seeing if the problem persisted consistently when it got warmer. 2.) There would be at times a loud clunk when the gear finally engaged after pushing the accelerator.

I have a repair manual for the van which has a trouble shooting guide and it said to check the universal joint. I did, and it seemed intact, rust free, and fine. I researched it a little more and did not see any indications that this was an awful horrible problem, so again, I decided to wait until the weather changed to investigate further. Problem: One day I drove the van to north Austin and left it in a parking lot for a few hours while I went inside. When I came back out and started the vehicle it would not engage 'drive' no matter what I did. It has since been sitting in the parking lot for about 2 weeks and the owner finally gave me the boot so I pushed it out onto the street.

What I have tried: I found a leak where the transmission fluid connects to the radiator (a hose was clamped too hard) and seemed to have fixed that problem. So that solves the problem of why there was low fluid in the first place. I took the doghouse apart and replaced a few vacuum lines that were extremely worn and damaged. At one point this was causing the van to stall immediately after starting, but have since been fixed. I checked the shift linkage where it connects to the transmission housing and, luckily, was able to view the dial on the transmission case where it connected; all moves of the shifter do in fact engage the dial and turn it. I pulled the two electrical connections off of the transmission housing to inspect them for burns or corrosion, although I would doubt reverse would work if they were damaged, and found none. They seemed to be in fine shape. The throttle cable seems to be fine. The speedometer cable is missing I believe because I can't find it and the speedometer doesn't work. However, unless I'm missing something this wouldn't cause the problem. Fluid seemed dirty, but I did not feel that is had be roasted over a fire pit (indicating burned out parts?)

Possibilities: I am going to drop the pan today I hope and investigate a little further inside the transmission. The transmission fluid does NOT seem to be getting any hotter than luke-warm. From what my manual tells me this should not be. Transmission fluid should get to a point where it is too hot to comfortably touch. I am wondering if this could be caused by one of three things a.) Broken pump not circulating the fluid b.) Clogged filter - fluid unable to circulate c.) No vacuum - not allowing the pump to get adequate air pressure to operate. I am wondering if, maybe, the fluid is not being warmed enough to expand correctly to let the transmission operate.

I have heard that these go bad, but are cheap and easy to replace. I have put this option off because I'd assume the regulator controls more than one thing and so if it were broken something like say, the fuel system would be affected as well. Maybe I'm wrong? Could it also be the hose itself? I think there is also a short somewhere in the electrical system, although I think it's located in the heater wiring, because the battery will drain heavily when it rains and the heater is engaged. I have read somewhere that this may cause the transmission not to operate properly, but it seemed to me like it is something else. In any case, I have been stuck in Austin now for quite some time, don't have money to pay a shop 2,000 to diagnose, over charge me for parts, and charge 10 hours of labor for a rebuild when you can buy these transmissions, it seems, for relatively cheap. I am hoping this is a relatively simple problem that someone here would be able to recognize and diagnose, or at the very least be able to say: "Check and fix these 4 things and come back." I'm trying very hard to learn this car inside and out and the repair manual I bought doesn't want me playing with the transmission at all - simply says "take it to a pro chump"