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taking a while to shift........th350. possible if motor can suck brake fluid....?????

Discussion in 'The Garage' started by down4thakrown, Sep 20, 2005.

  1. down4thakrown

    down4thakrown 1/2 ton status Premium Member GMOTM Winner

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    as i start from park it seems like the only way the tranny shifts is when im giving it gas and it has a mild shift kit and its a th350/205. could it be a vacuum leak? and my master cylinder is leakin pretty bad from what it looks like it's coming from the lid. im guessing that the gasket is gone to where the master cylinder bolts to the power brake booster. could this cause a vacuum leak????maybe sucking in brake fluid??????
     
  2. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    If it pauses and won't drive until you give it gas , its low on fluid most likely .
     
  3. down4thakrown

    down4thakrown 1/2 ton status Premium Member GMOTM Winner

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    last time i checked the tranny fluid it was a little over filled. i dont have the kick down cable hooked up. its like where im goin from a dead stop and it seems to take a while to shift into 3rd compared to my other truck that has the same tranny built by the same shop. maybe its just the cam
     
  4. gmcjimmy90

    gmcjimmy90 Registered Member

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    check your vaccum line going to the modulator valve also you may have to buy an adjustable modulator vave(if yours isn't). You may want to check the kick down cable to make sure it hasn't got pulled out any.
     
  5. down4thakrown

    down4thakrown 1/2 ton status Premium Member GMOTM Winner

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    im probably just goin replace that hard line with a long rubber one just to see if that's what it is. mines pretty bent up, so bad that its works better up side down :crazy:
     
  6. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    K , thought you meant from Park to drive .
     
  7. diesel4me

    diesel4me 1 ton status Premium Member

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    late shifts...

    The shifting is controlled by the vacuum modulator and the govenor--if the modulator loses vacuum due to a leak,bad hose or metal line,or a bad diaphram,it will shift late and a bit firmer than usual,and feel like it goes into neutral when coasting..--the govenor can do it too,if its weights stick or stronger springs were installed..

    The detent cable SHOULD be hooked up--if it isn't it might affect the shifting and the pressure to the clutches--push it IN all the way and tape it there if you feel you must run it disconnected..I'd hook it up and adjust it correctly if I were you,just to be safe..I've run a few TH350's with it disconnected for a long time with no issues though,but it felt better when I finally did hook it up and adjusted it right..

    Its possible for a master cylinder with a faulty seal in the rear of it to leak into the power brake booster and allow brake fluid to be burned in the engine..if the diaphram ruptures in the booster,it can cause a vacuum leak in the bottom of the master cylinder at a bolt hole in the casting..my 79 C10 did that about a year ago.. :crazy:
     
  8. down4thakrown

    down4thakrown 1/2 ton status Premium Member GMOTM Winner

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    im goin to try to replace that vaccuum line, then the diaphram. but the tranny has just been rebuilt.
    the power brake booster and master cylinder are brand new. luckily i got the life time warr.
     
  9. down4thakrown

    down4thakrown 1/2 ton status Premium Member GMOTM Winner

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    so i decided to check my brake fluid b4 i went to work and im glad i did cuz the back resavoir was almost empty. then after filling it i checked it after popped the hood to see if it had been leakin and how bad.......and it was really bad. there was brake fluid dripping off the the bottom of the pwr brake booster. and i can tell its comin from the lid of the m/c. how can i prevent this from happening again when i replace it. ????????
     
  10. diesel4me

    diesel4me 1 ton status Premium Member

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    probably the master cylinder,...

    My 82 K20 is doing the same thing--I fill the rear resivoiur in the master up--a day later its on the ground!--I can see it drip out of the back of the master cylinder--I suspected a leaky cover gasket too--so one day I filled it and left the cover off all day(a nice DRY day,to keep moisture out of the brake fluid!)..it drained out within 8 hours!--I have hydroboost,being a diesel,but thats no different than having the vacuum assist--a bad master cylinder rear seal leaks on both the same way!..now I need to get a rebuilt master cylinder... :doah: :mad: you probably do too!.. :crazy:
     
  11. down4thakrown

    down4thakrown 1/2 ton status Premium Member GMOTM Winner

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    that sux man, i just put this one on. i dont know why it leaks and i dont wanna warranty it out if its just goin to leak again. should i make sure the clip that holds down the lid is not bent or anything???????
     
  12. diesel4me

    diesel4me 1 ton status Premium Member

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    Check..

    It's possible its leaking out of the cover or gasket..thats why I left my cover off one day and didn't drive the truck--when I saw it was nearly empty after sitting,I figured it wasn't leaking out of the cover...--plus I watched a few drops drip on the ground!..its not impossible for a fresh rebuilt master to leak...but make SURE no rear brake lines,hoses,or wheel cylinders are leaking first!! :doah: :crazy:
     
  13. down4thakrown

    down4thakrown 1/2 ton status Premium Member GMOTM Winner

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    i got disc brakes in the rear on my 14bltff and the stock 83 propo. valve. but, its a 76 master cylinder and pwr brake booster. im using the stock 83 hard lines that go to the master cylndr. mine drips all the time i gotta fill it up every 2 or 3 days.
     

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