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"sputter sputter" (also pops the oil filler cap off) some ideas?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by muddin4fun, Nov 12, 2001.

  1. muddin4fun

    muddin4fun 3/4 ton status

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    \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    My blazer isn't feeling too good [​IMG]. It was low on fuel and it got real humid overnight and the temp dropped too before I filled it up(just some background info). So, I filled it up last night. This morning on the way to work, the throttle response started sucking. Then, while holding a constant speed, it would sort of gallop. Not bad, but I could tell. When it's in D and stopped, the idle sucks. It's not missing, just rough. I put some additive in the tank thinking that maybe I got some condensation or bad gas. I've been drivng it around for a while and it hasn't helped. I'm wondering if the distributor is advancing properly. Is there a good way to check it? Also, it keeps popping the filler cap on the valve cover. Why would it do that?

    Peace and stuff [​IMG],

    Muddin

    <a target="_blank" href=http://www.geocities.com/muddin4fun79blazer>www.geocities.com/muddin4fun79blazer</a>
     
  2. Chris Demartini

    Chris Demartini 1/2 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    <font color=blue>You could check the timing advance with a timing light. Bring the RPMs up and watch the light on the harmonic damnper advance. The popping filler cap leads me to belive there is excessive crankcase pressure (clogged or closed PCV).
     
  3. muddin4fun

    muddin4fun 3/4 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    the cap is a cheapo. I might get another one and just see. The motor and everything is brand new along with the pcv.

    Peace and stuff [​IMG],

    Muddin

    <a target="_blank" href=http://www.geocities.com/muddin4fun79blazer>www.geocities.com/muddin4fun79blazer</a>
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    I'm with Chris on the PCV valve causing excessive crankcase pressure. As for the distributor, you could remove the cap and see if the centifugal weights are sticky or if they move freely.

    It actually sounds as if the carb is leaning out...giving you a bad idle and a surge at cruise RPM's. Vacuum leak maybe?
    Maybe the vacuum to the vacuum advance has come loose?

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
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  5. Hossbaby50

    Hossbaby50 3/4 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    I agree. Pull your PCV valve, and see if it rattles. If it does then its ok. Also check all your vacuum lines and make sure they are all hooked up right. One time I change my spark plugs, and when I went to drive it it ran like s*it. I thought it was the plugs at first, but then I went over my vacuum lines, and I had knocked one off and didn't notice it. Plugged it back in and it ran fine.

    My Chevy isn't broken, its just out of gas.
     
  6. solowookie

    solowookie 1/2 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    man muddin with that nice new 383 I hope nothing serious is wrong... [​IMG]

    <font color=blue> Jeff - may the force be with you</font color=blue>
    <a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>link to k5's</a>
     
  7. HarryH3

    HarryH3 1 ton status Author

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    I hope it's nothing serious, but it sure sounds like there is some serious blow-by somewhere in the engine. [​IMG] Not the sort of thing that should be happening on an engine that fresh. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  8. muddin4fun

    muddin4fun 3/4 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    I'm gonna check all the easy stuff first. If there's something wrong with the engine, it's still under warrentee [​IMG]

    I'm gonna pull the plugs tonight also to see what they look like. If it was a motor problem, it would be in the valves correct? Which would possibly coat the plugs with oil? Is that correct?

    Peace and stuff [​IMG],

    Muddin

    <a target="_blank" href=http://www.geocities.com/muddin4fun79blazer>www.geocities.com/muddin4fun79blazer</a>
     
  9. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    Do you have an oil pressure gauge? I read in one of the mags recently about how if you use too much RTV to seal up your engine gaskets, you could end up blocking oil passages....that would cause HIGH oil pressure as the symptom......maybe blow the cap off too?

    I don't know if this could be what's happening, but in the article they pulled the covers off, carefully cleaned the RTV out of the passages and were lucky enough to have the engine work great after that.

    They did mention that using excess RTV sealer on a diff cover is no big deal, any extra there gets "chewed up" really quickly by the ring gear and pinion......unlike what happens when it starts circulating in the oiling system of the engine.

    -Greg72
     
  10. Emmettology 101

    Emmettology 101 3/4 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    Somethign is definately causing too much crankcase pressure to blow off the filler cap. The PCV is probably th culprit.. But on a new engine I imagine you used a new pcv valve.. And being that new there is probably somethign wrong if it is clogged!

    Mike

    <font color=green>"1024x768x256... Sounds like one mean woman."</font color=green>

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  11. Chris Demartini

    Chris Demartini 1/2 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    <font color=blue>Her PCV may be fine but if its not getting vacuum it wont be doing a thing.
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    I'd suspect the vacuum to the pcv is unhooked or damaged. This could explain the cap getting blown off and the bad idle and driveability due to a vacuum leak...

    Rene

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

    muddin4fun 3/4 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    that's what I'm gonna check.

    How strong is that vacum? Can I take the hose off the carb and put my finger over it and feel it?

    Peace and stuff [​IMG],

    Muddin

    <a target="_blank" href=http://www.geocities.com/muddin4fun79blazer>www.geocities.com/muddin4fun79blazer</a>
     
  14. dogman

    dogman 1/2 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    I'd throw a new fuel filter at it just for ducks, they're cheap; and have solved many problems.
    gas-n-sledge from the bottom, will clog.

    this is not your problem, not with a new motor. you shouldn't be getting oil out of the valve stems yet..
    but if your checking the valves out, when the covers are off. turn it over, put you hand on the rockers. are they going up and down the same? its a crude way to tell if you have a flat cam problem without measuring them.
    good luck.
     
  15. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    <blockquote><font class="small">In reply to:</font><hr>

    Can I take the hose off the carb and put my finger over it and feel it?

    <hr></blockquote>

    Yes...should be able to hear it too.

    Rene


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

    muddin4fun 3/4 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    Thanks guys for your help. I'll sheck it out tonight and give an update [​IMG]

    Peace and stuff [​IMG],

    Muddin

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  17. muddin4fun

    muddin4fun 3/4 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    Well...the plugs were fuel fouled. Swapped them out and it runs great! No oil or anything. I still don't know wy the oil cap pushes out. The pcv is in good shape, no leaks, and the carb is creating the vacum. I'm gonna try a different style to see if it's just the design or something. They are cheap valve covers and the cap was also cheap. Maybe they don't mix well?

    Peace and stuff [​IMG],

    Muddin

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  18. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    The carb doesn't create the vacuum. :) It's just where you tap into it.

    Either way, I'm glad to hear it runs better again. I'd try to find the source of the fuel fouled plugs. Is your choke sticking?

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  19. Gandolf

    Gandolf 1/2 ton status

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    Re: \"sputter sputter\" (also pops the oil filler cap off) some ideas?

    Glad to hear you solved the problem. If your plugs foul again, you might try going to the next higher heat range.


    '89 K5 Silverado..."You can’t have a real adventure, unless the outcome is truly uncertain".
     
  20. muddin4fun

    muddin4fun 3/4 ton status

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    Re:

    I meant by the carb was sucking thru that hole...thing...there...anyway...
    It was running like the same thing again this morning [​IMG]. I checked the choke last night and it's not sticking and it's adjusted right. I'm thinking that it's not warming up (plugs indicated running rich which could be the choke because it's not warming up and it basically is running like it's not warmed up.). So, I'm going to get a new thermostat. The temp guage is showing on the cool side, so maybe that's it. I'll put that in tonight. Work sure does get in the way alot! [​IMG]

    Peace and stuff [​IMG],

    Muddin

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