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Pinging after changing thermostat

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by jshadwick, Mar 9, 2003.

  1. jshadwick

    jshadwick Registered Member

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    Hi everyone, thanks for the great advice. Here goes:
    I bought an 87 k5 about 3 months ago, and noticed that it never heated up (the engine or my heater). So after checking the thermostat and recognizing that it was a 160 degree t-stat, I changed it to a 195. Now i got plenty o' heat, but now it pings at/near WOT and make a metalic "flitter" kinda sound (?). Then the check engine light comes on.
    *As long as I am fairly gentle with the pedal, no pinging or check engine light.
    I am going to change the t-stat back to the 160 degree one, because I think there may have been a "chip-transplant" that I was not aware of. Does this theory pan out with anyone else??
    thanks,
    James
    87 k5, new (10K) GM goodwrench 350 with stock TBI on an Edelbrock Performer TBI intake. /forums/images/graemlins/usaflag.gif
     
  2. MudNurI

    MudNurI 1/2 ton status

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    I dont think the thermostat has anything to do with your pinging- my 86 has a 195 in it and it doesnt ping..

    the only time my check engine light has come on- is when it was outta oil- dont laugh- it was literally out of oil

    Brandy
     
  3. jshadwick

    jshadwick Registered Member

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    Well, maybe i was not clear.
    It did not ping with the 160 degree t-stat. It Does Ping with the 195.
    I am hypothesizing that a previous owner replaced the stock computer chip with a "high performance" chip. The hi-po chips
    often come with a new, lower temp thermostat to adjust for
    the new programming.
    james
     
  4. MudNurI

    MudNurI 1/2 ton status

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    ahhhh- ya got me on the chip stuff...

    Brandy
     
  5. 84_Chevy_K10

    84_Chevy_K10 Banned

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    Have you even checked your timing yet?
     
  6. jshadwick

    jshadwick Registered Member

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    nope, gonna do that to. I did change the intake manifold gasket at the same time (it was leakin'). Could that have messed up the timing?? /forums/images/graemlins/ooo.gif
     
  7. Highlander

    Highlander 1/2 ton status

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    yea if you pulled the intake and didn't get the Dist. back where it should be that could be your problem.
    Put a timing lite on it and see where it's at and go from there.



    Eric
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    nope, gonna do that to. I did change the intake manifold gasket at the same time (it was leakin'). Could that have messed up the timing?? /forums/images/graemlins/ooo.gif

    [/ QUOTE ]

    /forums/images/graemlins/smile.gifThere's your problem then. Set your timing correctly and your engine won't ping.
     
  9. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    I'm not sure what was available for "chips" in the K5's. I do know that some performance chips due come with lower temps t-stats to combat pinging due to timing and fuel curve changes. That may be it, or it could be incorrect timing that was masked by the lower t-stat, or pinging may have occured and a P.O. installed a lower temp t-stat to eliminate the pinging (although going about it the wrong way).

    I would check your timing first, but remember to do it with the black w/ tan stripe wire disconnected as it will disable the computer advance/retard. With this wire disconnected, engine warm and at idle, you set the timing to Zero.
     
  10. jshadwick

    jshadwick Registered Member

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    OK, timing was good. I thought it was...
    Also, I think that it pings when it is warmed up only.
    For the sake of testing, I gunned it getting on the freeway when it was not fully warmed up, and no ping. I didnt like doing that...
     
  11. SiredbyFire

    SiredbyFire Registered Member

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    sorry to bump a old thread ,but i have the exact same problem, and i cant seem to find the solution


    " OK, timing was good. I thought it was...
    Also, I think that it pings when it is warmed up only.
    For the sake of testing, I gunned it getting on the freeway when it was not fully warmed up, and no ping. I didnt like doing that..."

    help
    thanks
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    I guarantee the OP's problem was the aftermarket chip.

    If you've got one (hypertech, etc) dump it. They are absolute garbage. Reducing temp and running higher octane to run higher timing is stupid as heck.
     

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