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Thread: OT: would a defective oil filter cause knock in a GM 3.4l v6 (60 degree)...

  1. #1
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    Default OT: would a defective oil filter cause knock in a GM 3.4l v6 (60 degree)...

    perhaps some of you remember me posting about a chevy 3.4l that lost a intake manifold gasket and gargled some coolant for a bit. the first Oil change had some metal in it, so i've been changing it every 1k miles or so. very light sludge continues to come out of it. last weekend, i changed the oil (it takes about 4 quarts) with 10w30 and replaced one of the quarts with 15w40 diesel oil (i don't care if it doesn't "clean" by itself, i just want it to hold the sludge in suspension). replaced with purolator oil filter and drove about 30 miles that day. no problems......(JIC, i don't usually give it a full crankcase of oil. if 4 bottles puts it to 1/4 or 1/2 above min on the dipstick, i don't bother adding any more because i change the oil so much that i don't want to waste it). i "thought" i heard piston slap in the motor the day before the oil change. anyone want to tell me what piston slap sounds like, just so i'm sure? at any rate, my mother calls me and tells me that her husband said that the engine is now knocking (she says you can't hear it from inside the car). he might be hearing the same "slap" i though i was. they aren't driving the car anywhere, and i can't get a straight answer from anybody as to how much oil is in the crankcase right now. i'll be man enough to admit it if i didn't tighten the sump bolt enough, or left a filter gasket on there, causing it to lose oil, but:

    1. nobody can tell me how much oil is in there right now
    2. nobody has bothered to check the carport floor for leaks
    3. i drove the thing for 30 miles the night of the change...no weird noises,
    "..Torchinski v. Peterson that it is legal to carry a concealed weapon, so long the weapon is totally slick like a huge ass machine gun that you carry under a trench coat, like in the Matrix."


  2. #2
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    If there was metal in the oil at the change, it's had coolant mixed with the oil and it was sludged to start with chances are the filter isn't your problem.
    About the only "defect" a filter could have would be contamination or leakage.
    Souds like a tired neglected motor to me.
    "The gas pedal wouldn't go to the floor if it weren't meant to be there"

  3. #3
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    These motors are notorious for chewing up bearings - when the gasket lets loose. Chances are the lower in is pretty much shot. Not sure if you can get away with a crank kit or not.
    Derek A.
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    Is this the small block Chev with two cyls. lopped of and split crank journals?
    "The gas pedal wouldn't go to the floor if it weren't meant to be there"

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    check the glovebox, they usually ship with a full set of bearings from the factory.

    A piston sound is similar to a rod bearing (a little higher sound), these are also famous for the piston pins to get loose too.
    95 E34 530I V2.37
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  6. #6
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    after reading your multipost, why cant anyone even check the damn oil level?
    95 E34 530I V2.37
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    Those who make peaceful revolution impossible will make violent revolution inevitable.

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    unfortunately, the mod kept the wrong post. what this all comes out to is that they've already rested the blame on my shoulders for this, since i was the last one to "do" anything to the car--they won't say it to my face, however. i really don't feel like doing a damn thing to this car, but i don't want it to sit there for months or years if it has bought the farm.

    some background:

    car is 2001 chevy impala. was a company car for the current owner, who changed oil when the oil life monitor told him to. fleet paid for maintainence, so it really wasn't neglected. i suspect what happened was that a FI or something was leaking a lot of fuel into the motor over many years, causing the sludge that i see now. oil change clowns don't care, so nobody ever told him there was anything wrong. i strongly suspect that the chevy dealership that did the manifold gasket didn't bother to change the oil afterwards, and it may have run with dirty oil for 6 months or so. i was hoping that maybe i could get away with a pan drop and con rod bearing swap if i had to intervene? how hard would that or a con rod/main bearing swap be with the thing in the car? thanks.
    "..Torchinski v. Peterson that it is legal to carry a concealed weapon, so long the weapon is totally slick like a huge ass machine gun that you carry under a trench coat, like in the Matrix."


  8. #8
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    From what I can see you shouldn't be responsible. Explaining this to someone who doesn't get it is going to be hard I'll guess.
    Maybe remind the owner there was metal in the oil before.
    You might get lucky with just bearings if things haven't gotten too bad.
    A leaking FI won't cause sludge, it'll just wash down that particular cylinder and dilute the oil.
    "The gas pedal wouldn't go to the floor if it weren't meant to be there"

  9. #9
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    the oil life monitor is a warning measure. you should change the oil at a proper interval, the monitor is to warn you when you are past due.

    doing 1K intervals wont do much to reduce sludge. you need to actually clean it out. if there is visible sludge under the oil cap then you need to remove it. Auto-RX and LC20 are good desludgers that tend not to be so harsh on the engine. engine flush additives that you idle the car with before the oil change can cause issues.

    if there isnt visible sludge, change to a 5W40 synthetic oil and run 3000 mile changes, and throw a bottle of valvoline synpower oil treatment in to reduce piston slap. fill the crankcase to mid point, do a 20 min drive, check the level and fill as necessary.

    as ross said, fuel dilution wont cause sludge, it will actually remove it! but at the same time cause excessive wear to the metal components as it washes the oil off.
    Alusil, Dinan DME | ITG Air Filter | Eibach/Bilstein HD | 26/20 Swaybars | Iridium plugs | Depo/ProLumen HID | Optima batt. | no AC | Stoptech brake lines, Frozen rotors, brass bushings, Superblue

  10. #10
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    i guess if fuel dilution doesn't cause sludge, then so be it. there is, however, a big fuel dilution problem coming from somewhere, as the oil smells of gas within 500-1000mi after an oil change. its not heavy "sludge", its just that i can see the valvetrain is dark brown, and if you leave the oil filter off the fitting for a little while (like 20-30 minutes), a brown "nesquick" or "hershey's" chocolate milk powdered looking substance will begin to drip down from it.

    ps...i just went to the gm owner's piston slap page (www.pistonslap.com) (hehehe, gm engines, built "like a knock"). i've forgotten what the car sounded like, but with the wav file there, at least i have the reference for the next time i visit home. i'm going to see if any places in orlando offer the BG oil system flush, and tell the guy to take the car there before i do anything else for it.
    Last edited by ryan roopnarine; 12-03-2006 at 06:32 AM.
    "..Torchinski v. Peterson that it is legal to carry a concealed weapon, so long the weapon is totally slick like a huge ass machine gun that you carry under a trench coat, like in the Matrix."


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