Turbo 350 Shifting Problem --- HELP!!!!!!!!!

[jon72vega]

I went to a car show yesterday & put 365 miles round trip on my Vega, & ran into an up-shift problem.

On my way to the show, after a stop for gas, the transmission wouldn’t shift out of low gear.
I pulled over to the side of the road, stopped, shifted into reverse & the car backed up ok, & shifted thru all the positions, then took off & it up-shifted normally.
I had this happen several more times after stops & starts.
What I did after that (when the problem occurred) was select low gear while moving, & shifted manually thru the gears. Some times it would up-shift immediately, other times there would be a delay, & it would shift at a higher rpm than what you would expect.
I did check the fluid level, (it was ok), the transmission never seemed to be slipping, it just didn’t want to up-shift.

THEN, THE PROBLEM WENT AWAY!
On the way home, I only experienced the problem once, (right near the beginning of the return trip), & had the same numerous stops & starts.

Here are some specifics of my combination.
The kick-down cable has never been hooked up in the 27 years I have owned the car.
I have an auxiliary trans cooler in front of the radiator, & do not run the trans fluid thru the radiator cooler.
The torque converter is an unknown brand, (I assume not stock GM because it is painted blue), & it looks to be about 11â€

[cjbiagi]

Jon, 2 things to check are the vacuum line and modulator as well as the govornor on the side of the trans behind a round cover. It could be a bad modulator (easy), I would check or replace that first. The govornor has some weights and springs that control shift points, it could be something with that too. It's pretty easy to pull out, there's a snap spring that holds a round cover on, once you remove that you can slip the govornor out and take a look at it. Of course this all assumes that you have checked the obvious which it sounds as though you have. You may want to look close at the shift linkage and make sure everything is adjusted and nothing came loose. Could be a collapsing vacuum hose too.

[2lucke4u]

Jon
Hate to state the obvious,,fluid and filter,yes fluid breaks down,, clogged filter,,try fixes on the cheap stuff first and go from there,,I'm guessing the fix will be simple,,in my limited experience when something major is wrong with a trans,the problem does not come and go,,good luck
Charles

[starfire383]

Modulator first and foremost

[ozzymoose]

im with the guys as well, should be something minor. you said that you havent changed oil in a while.. would do that with the tranny filter, 5 years is a long time for a transmission even if it dont do many miles. change the vac line, they are cheap and get pinholes or collapse. also you said you havnt had the kickdown attached for years..... the tranmission end of it hasnt worked its way into the kickdown position by any chance has it?? Check your cooler hasnt got a blockage. then gov/mod.

my money is on the vacuum tube, is my uneducated guess from 1/2 way around the world.

[cosvega76]

Jon,

I suspect you had a piece of debris in one of the valve body valves. I would agree and recommend to change the fluid and filter.

Chuck

[MIKESMONZA]

ALSO THE IF THE MODULATOR IS GOING BAD IT WILL LEAK A SMALL AMOUNT TO LARGE OF "ATF" UP THE VACUMN LINE ACCELARATING THE RUBBER HOSE'S DETEROIATING FROM FROM HEAT AND OXIDATION,,,,MAKING FOR ERATIC OPERATION,,, AND A BONUS OF THE THE OIL PULLED UP THE TUBE TO THE INTAKE TO BE BURNED IN THE COMBUSTION PROCESS LEAVING WHITE SMOKE OUT THE EXHAUST,,,, SO CLEAN THE LINE,,,, AND REPLACE WITH GOOD QUALITY HOSE,,,,,MIKE

[Elfmagic]

Also make sure the govornor drive gear is not starting to wear out, if it has a point where the teeth do not engage this will cause this kind of condition and i guess gm has had some problems with this.

[2lucke4u]

Jon
Now your going to have to tell us what the fix was,,its like waiting to open a present,,
Charles

[jon72vega]

Guys,
Thanks for all the replys!
I still haven't had the opportunity to look into this yet, but hopefully by this weekend I will be able to.

I will check out the linkage, change the fluid & filter, & replace the vacuum modulator. (the modulator is not much money).

I also will be replacing the entire vacuum line running up to the engine. Don't ask, but I have been using a hose (instead of tubing) for the entire length for almost the entire 27 plus years I have owned the car. After doing some research on the net, I understand that is a BIG No-No!!!!! It would be nice to be able to find one pre-bent even if it was used, but I will probably buy a piece of tubing the correct diameter at the auto parts store, & bend it myself.

If that doesn't take care of the problem, I guess it's governor time.

Again, thanks for all the replys!
I will post an update after I go thru everything I need to.

[jon72vega]

I finished up servicing the transmission today, & took it out for a 19 mile drive of mixed city & freeway driving. It worked perfectly!!!!!
(The last 170 miles of my return trip home last weekend it worked like it was supposed to, so the true test will be over time, to see if it stays working well).

Here's what I did:
I changed the filter & fluid. (Fluid didn't stink, but was dark & little thick---there wasn't much debris in the pan).
Installed a new vacuum modulator. (It had at least an ounce of fluid in the hose connection side---didn't look or smell like ATF or gasoline--- don't know what it was, all I know is it is supposed to be dry).
I ran a new steel tube for the modulator line. (The old hose that I removed didn't look like it was leaking but it was sure time to replace it).
I checked the shifter & cable out against every transmission detent position, & that was ok as is.

Thanks again guys,

[cjbiagi]

Jon, sounds good. Fluid in the modulator hose, huh? That surely could have been part of the problem. Sometimes a bad modulator will allow fluid to be drawn from the trans, could have been that or maybe some condensation that occured over time. Hope all is well.

[ozzymoose]

Good stuff, sounds like you have found your prob. The old hose may have been allowing moisture to seep through??????.......Jon I think a 200 mile cruise is in order just to make sure lol. Take some pics of the country side for me.