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Cruise Control

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Mastiff, Aug 2, 2003.

  1. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Does the cruise on an 83 K5 automatically suck from the factory, or did I do something to ruin mine? It totally surges all the time, like just going over a bump and it'll be going fairly wild on the throttle. Not to say it isn't working though, it does keep the speed within a few MPH, it's just annoying.

    I do have lower gearing and more power than stock. Anyone know if there are any adjustments possible?

    I realize this isn't a hardcore offroad related question. /forums/images/graemlins/tongue.gif
     
  2. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Mine worked ok on my 85k5 but it started losing vaccum and I would gradully lose speed. It would surge at lower speeds but not at 50 and higher. I disconnected it when I put my 406SBC in and don't remember how it worked. Does anybody have a diagram for the cruise?

    85K5 3/4ton,14bolt,10bolt,9"lift,35"boggers,16.5x14 welds, big horse 406SBC/700R4 /forums/images/graemlins/k5.gif /forums/images/graemlins/angryfire.gif
     
  3. Muddytazz

    Muddytazz 1 ton status

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    electrical diagram?
     
  4. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Yeah or if someone can tell me how the thing works and what has to be plugged into it to work. It looks like there is a vaccum plug on top of the diaphram looking thing that is connected to the throttle, is that it?

    85K5 3/4ton,14bolt,10bolt,9"lift,35"boggers,16.5x14 welds, big horse 406SBC/700R4 /forums/images/graemlins/k5.gif /forums/images/graemlins/angryfire.gif
     
  5. DrMaserati

    DrMaserati Registered Member

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    [ QUOTE ]
    Does the cruise on an 83 K5 automatically suck from the factory

    [/ QUOTE ]

    Probably. I've had cruise from all of the big 3, and GM is my least favorite because of this kind of stuff, but it shouldn't be that bad.


    [ QUOTE ]
    Anyone know if there are any adjustments possible?


    [/ QUOTE ]

    Yes, there are. First make sure there are no vacuum leaks. Vacuum leakdown at the servo should be no more than 5" per minute. Simplest adjustment is the link that connects the power unit to the carb. Where the slotted link goes on the stud at the carb there should be .020 to .040 inch clearance.
     
  6. Mastiff

    Mastiff 1/2 ton status Premium Member

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    [ QUOTE ]
    Yes, there are. First make sure there are no vacuum leaks. Vacuum leakdown at the servo should be no more than 5" per minute. Simplest adjustment is the link that connects the power unit to the carb. Where the slotted link goes on the stud at the carb there should be .020 to .040 inch clearance.





    [/ QUOTE ]

    Between what and what? /forums/images/graemlins/tongue.gif Mine has a long slot, are you saying with no vacuum it should be toward one end or the other?
     
  7. DrMaserati

    DrMaserati Registered Member

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    [ QUOTE ]

    Between what and what? /forums/images/graemlins/tongue.gif Mine has a long slot, are you saying with no vacuum it should be toward one end or the other?

    [/ QUOTE ]

    Where that slot goes over the stud on the carb. Before the CC is engaged, when there is no vacuum to the power unit, there should be .020 to .040 travel before the long slot actually pulls on that stud.

    I wish I could draw you a picture, it would be much easier to understand. The factory service manual actually has pictures for reference. Your best bet would be to get ahold of a service manual. It will give you the entire procedure for testing and adjustment. If I could figure out how to get the picture out of the manual and into a post I would do that.

    The servo and power unit are the same thing. I didn't realize until I read your last post that I had used both terms, which makes it confusing. /forums/images/graemlins/confused.gif It's that large round thing with the diaphragm in it.

    JP
     
  8. Thunder

    Thunder 3/4 ton status

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    Surging problems also can be caused by vacume leaks. Check all the vacume lines/connections. There is also a vacume switch on top of the brake pedal that turns off the cruise when you hit the brakes that can go bad or out of adjustment that will cause surging. If you have a manual trans there is one on the clutch too.
    When you hit a bump it may be jiggling the pedal enough to drop vacume and cause the surging.
     
  9. Mastiff

    Mastiff 1/2 ton status Premium Member

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    That makes sense. I do have the manual though too, didn't even think to look there. /forums/images/graemlins/tongue.gif

    I'll look in there when I get home. It may just be that it doesn't work well with low gears and powerful motor, too much throttle response. /forums/images/graemlins/thumb.gif
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    How's your speedometer? I *think* '83 trucks still had the fender mount transducers (2 piece cables) but I'm not positive. Cable fluctuation can mess with that style for sure, although even the electric ones (still cable speedo though) can be influenced by cable problems.

    ("Electric" cruise uses a box over the gas pedal to control it, VSS being one input. Earlier style used the transducer, but not sure how that works. Both use vacuum.)
     
  11. Mastiff

    Mastiff 1/2 ton status Premium Member

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    [ QUOTE ]
    How's your speedometer? I *think* '83 trucks still had the fender mount transducers (2 piece cables) but I'm not positive. Cable fluctuation can mess with that style for sure, although even the electric ones (still cable speedo though) can be influenced by cable problems.

    ("Electric" cruise uses a box over the gas pedal to control it, VSS being one input. Earlier style used the transducer, but not sure how that works. Both use vacuum.)

    [/ QUOTE ]

    My speedo is kinda flakey sometimes, like the needle sort of bouncing around. I think it's pretty standard to be able to hear the speedo spinning, especially when cold. I've tried lubing it before, but it didn't do much. I'm pretty sure mine goes directly from the guage to the T-case.

    Maybe I'll try lubing it again. Any suggestions on what to use for lube?
     
  12. DrMaserati

    DrMaserati Registered Member

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    [ QUOTE ]
    I think it's pretty standard to be able to hear the speedo spinning, especially when cold. I've tried lubing it before, but it didn't do much. I'm pretty sure mine goes directly from the guage to the T-case.

    Maybe I'll try lubing it again. Any suggestions on what to use for lube?

    [/ QUOTE ]

    You should not hear any noise coming from the speedo or it's drive cable. If the needle is jumping it is almost invariably a cable problem. If you're going to lube it again, clean out the cable housing by flushing it with solvent first.

    Make sure you inspect the cable for damage. It should be very smooth and have no kinks. If you clean and lube and the needle still jumps, there is probably either a small kink or some damage to the cable housing. Time to replace it.

    There is speedo cable lube available. Something else that works well is Vaseline with powdered graphite mixed in it. White lithium grease is commonly used. If I'm not mistaken it gets pretty cold in Iowa. You want something that won't solidify when it gets cold.

    JP
     
  13. Mastiff

    Mastiff 1/2 ton status Premium Member

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    My dad owned this truck in Arizona when I was still too young to drive, and I remember being able to hear the speedo even then. This is like in 1983 when the truck was brand new.

    If I recall, I need to get at the cable from the inside? Like pull out the bezel thing and lenses, etc? There's no way to get at it from the engine side is there?

    Thanks.
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    I think you are right about removal. Gauge side only IIRC, but it's been awhile. You could unhook it from the t-case and try pulling the cable that way though I guess. It won't take much effort if it's gonna come out.

    The GM test for the cable is to pull the whole thing (including the sheath), hold both ends in your hand, and turn one end of the cable. If the sheath "flops" around on you, you need to replace the cable.

    I had been told before that graphite is NOT a good lube, (by a locksmith, who told me to never use it on locks) but it is so commonly used, I'm not sure what to think. I still have a feeling it's like slick50...teflon is a solid (and so is graphite) and is not a good lubricant because of it. I wouldn't put sand in my oil, just because it was tiny grains of sand (or whatever) doesn't mean its a good lubricant.

    They make something called "cable-ease" (not sure on spelling) but a friend used it and had good luck, and always recommends it. I've used lithium grease before, but not sure if it's up to the long-term task of dealing with a cable that spins as fast as the speedo cable does.
     

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