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Dipstick ejection option

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by AZK5, Jun 7, 2001.

  1. AZK5

    AZK5 1/2 ton status

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    Does anyone here know why my TH350 dipstick pushes out a couple inches everytime I drive the K5?
    CB

    1973 K5, 400TPI,TH350, 203/205, Dana60/Detroit/5.38 front and rear, 38" TSL's on steel wheels
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  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Vent line plugged?

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  3. muddin4fun

    muddin4fun 3/4 ton status

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    Sounds like you have a vent line plugged up.

    <font color=red>I'm a psychic amnesiac. I know in advance what I'm going to forget. </font color=red>
     
  4. AZK5

    AZK5 1/2 ton status

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    Is that the only thing that can do that? I can see the vent tube and see into it with a flash light, it doesn't look plugged and it's not crushed.
    CB

    1973 K5, 400TPI,TH350, 203/205, Dana60/Detroit/5.38 front and rear, 38" TSL's on steel wheels
    <A target="_blank" HREF=http://www.azk5.coloradok5.com>http://www.azk5.coloradok5.com</A>
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Its the only thing that comes to mind...thermal expansion of the fluid. I know GM had a recall a number of years ago and they provided a locking dipstick for the auto's...you might want to replace yours with one of those if the vent isn't plugged.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  6. HarryH3

    HarryH3 1 ton status Author

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    2 more possible scenarios:

    1. The PCV valve is stuck closed, so the internal crankcase pressure has to find somewhere else to escape and blows the dipstick out of the tube.

    2. The rings are shot, or a ring is broken, and too much pressure is escaping past them and into the crankcase (called excessive blowby). The pressure exceeds what the PCV circuit can bleed off so it blows the dipstick out of the tube.

    Take off the oil filler cap and start the engine. Hold your hand over the filler (not tightly) as you rev the engine. If you feel a breeze coming out of the oil filler hole as you rev the engine, then you'll be looking at a rebuild soon. [​IMG]


    <font color=black>HarryH3 - '75 K5</font color=black>
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  7. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    HarryH3 is referring to the motor's dipstick, but I think the original post is referring to the Turbo-Hydramatic 350 Tranny. If it is, then the vent tube (like has been said before), or some internal venting (not sure what in there to vent) is not doing it's job. I have seen things vibrate loose sideways and down, but not usually upward, so I would think vibration is out of the question (but stranger things have happened).

    If you didn't built it yourself, how can you call it yours.......?
     
  8. HarryH3

    HarryH3 1 ton status Author

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    Yep! I saw "350", not "TH350". [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
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  9. AZK5

    AZK5 1/2 ton status

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    Maybe I'll try to pull the vent tube off and see if something is stuck in it. I'd like to get a late model sealed dipstick anyway but I'd like to find out what the problem is first.
    CB

    1973 K5, 400TPI,TH350, 203/205, Dana60/Detroit/5.38 front and rear, 38" TSL's on steel wheels
    <A target="_blank" HREF=http://www.azk5.coloradok5.com>http://www.azk5.coloradok5.com</A>
     
  10. Pugsley

    Pugsley 1/2 ton status

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    We had an HT740 Allison at work that did the dipstick ejection number - After weeks of scratching their heads, the mechanics came up with an innovative solution - The dipstick rode behind the seat, and a rubber stopper took it's place in the tube. It worked that way for close to a year.

    I'm so poor I can't even pay attention [​IMG]
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  11. dyeager535

    dyeager535 1 ton status Premium Member

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    I dont know if you can pull the vent tube if its plastic. How about some vacuum tubing hooked up to it that you blow through. Pull the dipstick out first though of course.

    Dorian
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  12. Mudstud

    Mudstud 1/2 ton status

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    I have had the same problem on my TH350. I figured since it was kind of stubborn going in the tube that there must be some static tension pushing up on the stick and so it just "sprang" up an inch or two with movement of the truck. I solved it by draging a spring off the stick handle straight down to the valve cover. Maybe I should check my vent tube just in case- where is it? It's not the line that comes off the modulator is it cuz if that gets pluged the motor will not run right at higher RPMs.

    Stuck is a state of mind!

    Mudstud
    76K5 sb400/350/203parttime/3.73-D44/GM12 locked
     
  13. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    If the vacuum line to the modulator gets plugged it should not have any effect on the motor. It just hooks to the intake as a source of vacuum to control shift points of the tranny. The only ill affect would be improper tranny shifts. As far as the vent tube, there "should" be a white hard plastic short tube with a loose cap (sometimes green) on top. The looseness of the cap allows air to escape when the fluid expands and air to pull in when the fluid contracts. If you are not sure what to look for, stop at any AAMCO or tranny shop and they should be able to give/sell you one. This way you will know what you are looking for and if you break it pulling it out to check it, you will have a spare. Plus I use them in the ends of my axle vent tubes. I run a flexible fuel line from my diff vents up to the highest out of the way point I can find, then stick the breather in the end of the tube.

    If you didn't built it yourself, how can you call it yours.......?
     
  14. Mudstud

    Mudstud 1/2 ton status

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    That's right's right. When my air cleaner was pushed down too hard against that vent tube (behind carb) I did get some really funking shifting- sorry- that is what I was reffering to in my previous post when I said motor would run funky. I didn't think it through!

    Stuck is a state of mind!

    Mudstud
    76K5 sb400/350/203parttime/3.73-D44/GM12 locked
     

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