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T-350 Vacuum line / 203 drain plug

Discussion in 'The Garage' started by ellero, May 3, 2007.

  1. ellero

    ellero Registered Member

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    I have an 84 K5 that had a 700r4 and a NP208. I broke them in half and not have installed a 78 T-350 / NP203 with a part time kit.

    The T-350 has a place to connect a vacuum line at the rear but my 700r4 never did because it was computer controlled. Can I connect this into any vacuum line by the carb, or is there a specific place it has to be run too? Also, what is the purpose of the vacuum conection on the T-350? I assume its important or it wouldnt be there. Also it is currently not connected to anything and the truck barley wants to move.

    Next is the NP 203 with the part time kit. Boy was that fun installing without a tranny jack. Does anyone know where the drain plug is on it? I found a filler plug in the rear, but cant find the drain plug anywhere. Please help as I need to get this thing running very soon. I am moving in a month.

    John
    im_john@msn.com
    760-214-8251
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    TH350 vacuum line needs to be run to a constant source of vacuum. Anywhere that has vacuum at idle will work.

    Vacuum line controls the modulator, which operates a valve increasing or decreasing shift firmness based on engine vacuum: high vacuum, low engine load, soft shift. Low vacuum, high engine load, hard shift.
     
  3. dremu

    dremu Officious Thread Derailer Premium Member

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    Draining a '203 is accomplished by loosening the bottom-most bolt, IIRC. There is no drain plug per se.

    The vacuum thing is the shift modulator, so yeah, things will be bad without it. It may go to a vacuum switch in the intake manifold before going to the carb. You really need a vacuum diagram for a '78 to set it all up right... lemme dig, see if I can find one.

    BTW, your 700R4 was not electronic -- that's a 4L60E -- but its shifting was controlled by a throttle valve cable, I believe they're called.
     
  4. dremu

    dremu Officious Thread Derailer Premium Member

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    Damn, Dorian beat me to it. =))

    -- A
     
  5. Randy92782

    Randy92782 1 ton status

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    well nothing to add here. it's all been said.
     
  6. Mudstud

    Mudstud 1/2 ton status

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    Does your engine have a port off the intake, right behind the carb? That is typically where the Tranny vaccuum lines attaches to.
     
  7. ellero

    ellero Registered Member

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    Not sure. Its an 84 so its got more vacuum lines than any other car I have ever seen. I will try to climb in and look but I am still recovering from a broken leg. I assume you are refering to between the carb and the distributor?
     
  8. Mudstud

    Mudstud 1/2 ton status

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    You assume correct.
     
  9. ellero

    ellero Registered Member

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    I was just out there and although I could nt get behind the carb with my lift and tires having the truck up higher, I did find the emmisions diagram right on the front abve the grill. The diagram shows a vacuum line from the main manifold vacuum source to the air pump and that line "T's" off to the air cleaner. Can I get another T conectore and split it off from betwen the manifold and air pump because access to the air pump line is easy?
     
  10. Mudstud

    Mudstud 1/2 ton status

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    Hmm, I guess if the T didn;t restrict the line (smaller ID) then it should work fine. If you experience strange shifts and surging then it's not getting enough vaccuum and you will have to pul it directly off the intake.
     
  11. ellero

    ellero Registered Member

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    It does have a vacuum line right off the intake behind the carb. I added a T about 8 inches off the manifold line and it has good vacuum. With the rear driveline disconnected and in 2wd, the transfer case barley turns. If I lock in the front axle with the front driveline connected, the truck wont move. Any more ideas, or did I just get suckered into buying a used tranny that was bad to start with.
     
  12. Mudstud

    Mudstud 1/2 ton status

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    Well why not hook it all up and take it for a spin? If you locked the front hubs and put it in 4wd it should have moved. That would be a T-case question. Play around with it and see if it all works out. Perhaps your shifters need adjusting??? I just heard of this trick in another post. FOrget which one right off.
     
  13. ellero

    ellero Registered Member

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    Adjusted the indents with my friend. They now line up under the truck as well as on the colum. With the motor off all af the t-case stuff locks and unlocks correctly. Also with the motor off, and the trany in park it all locks up fine. With the motor off and the tranny in D or R it will turn, easy in one direction and will take more effort to turn in the other direction. If I turn it by hand in gear, if makes a whining noise in the tranny. Im stumped because the T-case locks in and out of all 5 positions, the trany locks in park, but she wont move.
     
  14. Mudstud

    Mudstud 1/2 ton status

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    I'm confused about you saying it'll turn easier in one direction then the other. What are you turning- the drive shafts by hand? If it has a part time kit in it with the front shaft in and the rear one out and it is in 2wd (Which would be "H" as pictured below) then it makes sense that the truck didn't move cuz it would only spin the rear output.

    The "H" is your 2wd position when you have a part time kit.

    Just to make sure we are all on the same page the 203 shift pattern is like this- Starting all the way forward
    [​IMG]
     
  15. ellero

    ellero Registered Member

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    Correct. I have the front drive shaft in and when I pock in the front, the truck will not move in 4x4 mode. If I put it in 2wd with the rear driveshaft removed, the yolk barely moves. If I turn the yolk by hand with the motor off and the tranny in any position other than park, thats where its easier to turn one direction over the other and where it makes the noise. If I have it in 2wd or 4wd and the transmission in park, everything locks up solid like it should so that tells me that the transfer case is working.
     
  16. Mudstud

    Mudstud 1/2 ton status

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    Man I'm sorry but I'm at a lose. I'll think more on it though. Are you absolutly certain you are shifting into the desired gears on the t-case?
     
  17. ellero

    ellero Registered Member

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    Yes. But I have some good news. I had a break through tonight. I made sure that the torque converter had oil in it before I installed it and I made sure that the tranny was full and I even bought the correct dip stick and tube for the T-350. Well even with all the fluids reading full the only thing I could think of was the fluid level being off, so I decided to just keep dumping more and more iol in it and it would either move to I would start blowing seals. The next step is a new tranny so why not go for broke. I over filled it by 4 quarts and it worked. Maybe the pump was dry and not pumping it right untill it was over filled because it doesnt read too full now even though I did over fill it. I was able to pull it out of the driveway for the first time in 1.5 years by using the front driveline. Lets hope thats all it was. Thank you all for your continued effort and help.

    John
     
  18. Mudstud

    Mudstud 1/2 ton status

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    Progress is good. So did you determine it does or doesn't have a part tim ekit in it? You'r not dumping oil in the tranny are you?- You mean AT fluid right? You know as a tranny sits the fluid leaks out of the torque converter and back into the pan. As the truck is running it will pull fluid back into it there by lowering the fluid level in the pan. You need to keep checking it till it reads right when it's hot.
     
  19. ellero

    ellero Registered Member

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    Yes, Dex III AT. But now I have a bunch of oil under the truck that was not there before. It looks as if it is coming from the torque converter bottom cover. Could I have a bad front seal, or is that cover supposed to fill up with oil? I thought it was only a dust cover.
     
  20. ellero

    ellero Registered Member

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    And yes its a part time kit for sure.
     

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