Shifting issues

[haleybeast]

My son's '85 (mileag unknown) was having trouble shifting out of second gear. I read several blogs and the TM. This weekend I replaced all the vacuum lines, the modulator, and the vacuum regulator. No affect. Need some advice on nexts steps. Thanks

 

[Westech]

are you sure the vacuum pump is even working?
trans fluid at correct level and clean?
adjusted the modulator and TPS correctly?

 

[cpf240]

I'd suggest using a vacuum gauge to see if the vacuum pump is working properly.

 

[doghead]

I read several blogs and the TM

Did you follow the troubleshooting section of the -20TM?

 

[br44]

Hey I know this sounds odd, but change your fuel filter. I used to have the same problem getting out of 2nd and it ended up being the engine struggling to do anything, much less shift.

 

[cliffyp]

"Trouble shifting out", as in late shift, hard/harsh shift, doesn't shift? Does 1-2 feel normal? Open your governor door and pull out the governor to check it out. Also put a pressure gauge on the trans and see if it's making the correct pressure.

 

[haleybeast]

Thanks for the input. Odd thing is there is pressure up top at the regulator, but nothing getting to the modulator. I'm going to guage all the pressure, try those few things and check for leaks/breaks in the metal line.

 

[engineman2]

The vacuum regulator on the injection pump might have gone out or be poorly adjusted. I don't remember all the details about it but I'm sure someone more knowledgeable than me will chime in.

 

[doghead]

There are lots of good ideas posted here, but why not follow the troubleshooting procedure in the TM? It's organized and complete.

If that fails to find and correct your issue, then start guessing...

 

[Tow4]

I had the same problem with my M1028A2. If the vacuum pump is working; by pass the vacuum regulator at the injection pump. If it shifts, it's the regulator. Note that it may shift first to third very quickly, but you will know the transmission is shifting.

Good luck.

 

[Westech]

Good trick I forgot about that one.
But DH is correct.... use the TM and you wont have to waste a bunch of time grasping at straws on this issue.

 

[haleybeast]

Turned out to be a split in the metal pipe from the regulator to the modulator. I did a temporary bypass with vacuum tubing and shifts like a dream. Any ideas where I can get the metal piece or just easy to bend one myself?

 

[engineman2]

I don't know where you can get factory replacements. But I imagine that sections of steel brake line would work well if you just cut off the flared ends. The brake line is cheap and easy to bend so I'd suggest that. Or you could opt to stick with the rubber line and just secure it out of the way. Glad you figured it out!

 

[doghead]

Turned out to be a split in the metal pipe from the regulator to the modulator. I did a temporary bypass with vacuum tubing and shifts like a dream. Any ideas where I can get the metal piece or just easy to bend one myself?

So you did use the TM, must have figured it out with step#2.

51. WILL NOT SHIFT PROPERLY

Step 1. Check transmission fluid indicator for proper reading. (See TM 9-2320-289-10)

Step 2. Inspect vacuum hoses, vacuum pump, and vacuum regulator valve for improper

connection, leakage, or damage.

 

[cpf240]

You could look in the -20p and -34p TMs and get the GM part number, then google it...