1998 3.0 knocking after turning engine off!!

Discussion in '3.0 Engine' started by Bigcat84, Jan 29, 2013.

  1. Bigcat84

    Bigcat84 New Member

    I juss bought a 1998 ranger 3.0 4wd with 140,000 miles.it has a cope p0401.insufficient egr flow.i cleaned the egr port hole on the intake,and the metal hose goin to exhaust.i also cleaned throttle body and maf.there was a good bit of carbon so this weekend im goin to seafoam the hell out of it and change my oil to royal purple.but when i drive the truck,no matter if it just for a minute or for hours,when i turn the key off theres a knocking sound comin from my engine.it makes about 10-20 slow knocks the. It stops...anyone have any input on this?? And will this hurt my truck??
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  3. shovelmike

    shovelmike New Member


    What you are experiencing is dieseling. The combustion chambers are probably just as carboned up as everything else. The carbon effectively raises the compression ratio by occupying space in the chamber, plus, it gets red hot and ignites the mixture. As you have seen, the engine continues to run, but in a very random fashion.
    It is not good for the engine, puts a lot of strain on parts.
    The seafoam treatment will probably do much to clean it up.
  4. Scrambler82

    Scrambler82 Old Guy User

    ^^^ In the mean time, if you can, shut off the truck in gear.
    It put a strain on the engine and pulls it down when you shut off the key.
  5. OP

    Bigcat84 New Member

    The seafoam helped so far...i just ordered my screamin demon coil pack.whats are the best plugs and wires to run with it???
  6. Hooligan

    Hooligan Rangerholic!!

    Go with MotorCraft plugs and wires, that is what is recommended for the rangers and run the best. Also dont for get to gap the plugs at .065 for the Screamin Demon pack.

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