1991 c1500 compression issues

Discussion in 'Chevy Truck Forum' started by COUNTRYBUMKIN, Dec 4, 2008.

  1. COUNTRYBUMKIN

    COUNTRYBUMKIN New Member

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    I have 1991 c1500 with a 5.7 engine. all cylinders read 180 psi, but numbers 4 and 6 which read 60 psi any info would be greatly appreciated, by the way it 150,000 miles and has had oil changed religously every 3,000 miles
     
  2. silverhairdeere

    silverhairdeere Senior Member

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    could be a bad head gasket draining off into the radiator to carbon on valves , to bad rings , does it use much oil or anti-freeze , i probably wrong but it seems about all it could be .

    silver hair deere
     
  3. COUNTRYBUMKIN

    COUNTRYBUMKIN New Member

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    uses less than half a qt of oil between changes and not any coolant
     
  4. silverhairdeere

    silverhairdeere Senior Member

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    have a garage do a leak down test on the radiator , some more advanced garage have a meter to look for exhaust in the anti-freeze .if that ain't it i'am thinking a valve job , burnt valve , does it have a miss . hopefully one of the bigger brains will chime in .

    silver hair deere
     
  5. COUNTRYBUMKIN

    COUNTRYBUMKIN New Member

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    yes has a rough idle.
     
  6. silverhairdeere

    silverhairdeere Senior Member

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    i'am thinking the valves and i don't know of any other test other than a tear down . sorry .

    silver hair deere
     
  7. leolkfrm

    leolkfrm Full Member

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    when you were doing the compression test, did you squirt some oil in the low cyl? if the compression increases it's rings. if there is no change its a head issue, ie burnt valve, bad seat
     
  8. silverhairdeere

    silverhairdeere Senior Member

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    thank god someone with intelligents came along .:woot:

    silver hair deere
     
  9. COUNTRYBUMKIN

    COUNTRYBUMKIN New Member

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    no i did not do that but will, thank you for info
     
  10. bradrhale

    bradrhale Senior Member

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    be careful as leos head might swell up. that is a good idea and a great way to isolate the problem further. rough idle might be just from poor compression.
     

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