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Discuss 325 still knocking after valve adjustment,.. in the alt.autos.bmw forum at Car Dealer Forums; I posted earlier about my 325 with 145k miles that knocks for the first few ...
  1. #1
    cosmo
    Guest

    Default 325 still knocking after valve adjustment,..

    I posted earlier about my 325 with 145k miles that knocks for the
    first few minutes until it comes up to temp.
    Well, adjusting the valves didn't help any. They were fine except for
    two that might have been slightly loose by .01" or so.
    Could it be that one of the many sensors that control timing is
    defective? Maybe they kick out after they've done their job at cold
    start and the engine runs right after that.



    › See More: 325 still knocking after valve adjustment,..

  2. #2
    adder1969
    Guest

    Default Re: 325 still knocking after valve adjustment,..

    On Dec 18, 12:42 pm, cosmo <noth...@nowhere.com> wrote:
    > I posted earlier about my 325 with 145k miles that knocks for the
    > first few minutes until it comes up to temp.
    > Well, adjusting the valves didn't help any. They were fine except for
    > two that might have been slightly loose by .01" or so.
    > Could it be that one of the many sensors that control timing is
    > defective? Maybe they kick out after they've done their job at cold
    > start and the engine runs right after that.


    I can't remember whether you said or not (before) whether the knocking
    was in frequency with the cam or with the crank. There is such a
    thing as piston slap although I have no direct experience of it
    myself.

    You need to try to find where the sound is coming from really and only
    someone experienced with the different failure sounds could probably
    tell you that.

    I had a car once that was tapping and it turned out to be shapnel
    imbedded in the top of the piston. My dad's Saab had the little ends
    go. My GM sounded like the cam was on the way out but turned out to
    be water pump bearings.

  3. #3
    Bill
    Guest

    Default Re: 325 still knocking after valve adjustment,..


    "adder1969" <adder1969@yahoo.co.uk> wrote in message
    news:520a606a-90ce-49ee-ac20-f8c1ec03c24e@x69g2000hsx.googlegroups.com...
    On Dec 18, 12:42 pm, cosmo <noth...@nowhere.com> wrote:
    > I posted earlier about my 325 with 145k miles that knocks for the
    > first few minutes until it comes up to temp.
    > Well, adjusting the valves didn't help any. They were fine except for
    > two that might have been slightly loose by .01" or so.
    > Could it be that one of the many sensors that control timing is
    > defective? Maybe they kick out after they've done their job at cold
    > start and the engine runs right after that.


    I can't remember whether you said or not (before) whether the knocking
    was in frequency with the cam or with the crank. There is such a
    thing as piston slap although I have no direct experience of it
    myself.

    You need to try to find where the sound is coming from really and only
    someone experienced with the different failure sounds could probably
    tell you that.

    I had a car once that was tapping and it turned out to be shapnel
    imbedded in the top of the piston. My dad's Saab had the little ends
    go. My GM sounded like the cam was on the way out but turned out to
    be water pump bearings.
    -----

    Mine was Connecting Rod Bearings on #1 and #2 pistons in my '88 325is. It
    was heard the best when letting off the gas next to a wall or highway
    barricade/lane divider (to get the echo). That particular job was quoted as
    $2500 and the engine comes out. I did it for $60 including a new oil pump
    and bearings for all 6 pistons, and the engine stayed in the car (but I did
    have to lift it up about 3 inches off the motor mounts). Open to close took
    about 5 hours and a lift from the local auto hobby shop. Turns out the
    previous owner had a gasket failure and some coolant got into the oil. They
    fixed that, but the coolant ate little "worm tracks" into the Conn Rod
    Bearing shells. This created a low oil pressure situation and contributed to
    the "thunk" I was hearing. Oil pressure would be OK after a few extra
    seconds, but I knew something was wrong. After replacing the shells on all
    6, it was fine.

    Bill in Omaha
    '86 535i



  4. #4
    Jeff Strickland
    Guest

    Default Re: 325 still knocking after valve adjustment,..


    "cosmo" <nothing@nowhere.com> wrote in message
    news:ipffm3p7vuhab11cag1d987abi725j00ii@4ax.com...
    >I posted earlier about my 325 with 145k miles that knocks for the
    > first few minutes until it comes up to temp.
    > Well, adjusting the valves didn't help any. They were fine except for
    > two that might have been slightly loose by .01" or so.
    > Could it be that one of the many sensors that control timing is
    > defective? Maybe they kick out after they've done their job at cold
    > start and the engine runs right after that.


    Your car uses HYDRAULIC valve lifters. These are thin devices that are
    rougly the size of a small stack of nickels. The lifters are prone to
    getting an internal build up that restricts the free flow of oil, OR the oil
    flows properly but the spring inside gets stuck in such a manner as the
    lifter is slightly collapsed when cold.

    1.) There is very little you can do for this beyond adding a detergent
    product (automatic tyransmission fluid works here) to clean the contaminants
    out and hopefully regain full operation of the lifters. There are a variety
    of detergent-products you can add, automatic transmission fluid is what we
    used in the old days before the specialty products that may or may not work
    better.

    2.) Before we got hydraulic lifters, valve noise was common. A slight tap
    from the lifters (where the rocker arm contacts the top of the valve) is not
    a problem. It is an annoyance, but it is not a problem.

    3.) Cold weather plays into this trouble because the oil gets thick when it
    is cold, and thick oil does not flow through the very small orifices inside
    the lifters, causing them to tap until the oil gets warm. One of the
    available remedies is to use a lighter weight motor oil in winter. If you
    are using 10w40 now, try switching to 5w30 for winter use, then back to
    10w40 for summer.


    Hydraulic lifters expand to fill the space between the valve stem and the
    rocker arm so there is no noise coming from the valve train. When the cam
    lobe rises, the rocker arm presses against the valve stem, pushing the valve
    open. Because the valve has a very strong spring, some of the oil inside the
    lifter will get pushed out as the rocker arm pushes the valve. When the cam
    lobe falls, the rocker arm releases the valve which is closed due to the
    very strong spring mentioned earlier. There is a small spring inside the
    lifter to cause it to expand again to fill the gap that forms between the
    rocker arm and the valve stem. When the lifter expands, oil flows in and the
    valve train sits and waits for the cam to roll around again and start the
    whole process over.

    The problem you are noticing is that the lifter is not fully expanding when
    it is cold, and the tap you hear is the result of the small gap between the
    rocker arm and the valve stem. The cause of not expanding can be dirt/sludge
    inside the lifter, blocked passages impeding the flow of oil, or thick oil
    that is slow to run through the passages. Of course, a combination of all of
    these is possible as well. One other possibility is a broken spring inside
    of the lifter, but this would make a sound that remains after the engine
    gets warm.

    I said earlier that the lifter goes between the rocker arm and the valve
    stem, but this is not always the case. The lifter can go between the cam
    lobe and the rocker arm, and on a push-rod motor it will almost always rest
    on the cam lobe, with the push rod fitting between the top of the lifter and
    the rocker arm (the configuration of a push rod motor is not really germain
    to this discussion since your BMW does not use that design). The point
    being, the physical location of the lifter is not important, the job it does
    is what I wanted to describe. Once you understand what a lifter does,
    finding it is easy. The job of the lifter is to fill the small gap that
    exists between the rocker arm and the valve stem. There are engine designs
    where the cam makes direct contact with the valve stem through the lifter,
    in this instance the lifter will need some form of device to hold it in
    place. (Your BMW does not use this design either ... )

    Bottom line,
    You worry too much.







  5. #5
    Floyd Rogers
    Guest

    Default Re: 325 still knocking after valve adjustment,..

    "Jeff Strickland" <crwlr@verizon.net> wrote
    > "cosmo" <nothing@nowhere.com> wrote
    >>I posted earlier about my 325 with 145k miles that knocks for the
    >> first few minutes until it comes up to temp.
    >> Well, adjusting the valves didn't help any. They were fine except for
    >> two that might have been slightly loose by .01" or so.
    >> Could it be that one of the many sensors that control timing is
    >> defective? Maybe they kick out after they've done their job at cold
    >> start and the engine runs right after that.

    >
    > Your car uses HYDRAULIC valve lifters.


    Jeff, you're completely off on this. If you go back and actually
    READ the previous thread, you would discover that this is an
    '88 325i with M20 engine, which does not have hydraulic tappets.

    FloydR



  6. #6
    Jeff Strickland
    Guest

    Default Re: 325 still knocking after valve adjustment,..


    "Floyd Rogers" <fbloogyuds@hotmail.com> wrote in message
    news:13mg3jmlrcl0dfd@corp.supernews.com...
    > "Jeff Strickland" <crwlr@verizon.net> wrote
    >> "cosmo" <nothing@nowhere.com> wrote
    >>>I posted earlier about my 325 with 145k miles that knocks for the
    >>> first few minutes until it comes up to temp.
    >>> Well, adjusting the valves didn't help any. They were fine except for
    >>> two that might have been slightly loose by .01" or so.
    >>> Could it be that one of the many sensors that control timing is
    >>> defective? Maybe they kick out after they've done their job at cold
    >>> start and the engine runs right after that.

    >>
    >> Your car uses HYDRAULIC valve lifters.

    >
    > Jeff, you're completely off on this. If you go back and actually
    > READ the previous thread, you would discover that this is an
    > '88 325i with M20 engine, which does not have hydraulic tappets.
    >



    Well, except for that tiny problem, my explanation is good ...

    I find it odd that there are no lifters though.



  7. #7
    Tom K.
    Guest

    Default Re: 325 still knocking after valve adjustment,..


    "Jeff Strickland" <crwlr@verizon.net> wrote in message
    news:%wV9j.5649$8y4.1466@trnddc07...
    >
    > "Floyd Rogers" <fbloogyuds@hotmail.com> wrote in message
    > news:13mg3jmlrcl0dfd@corp.supernews.com...
    >> "Jeff Strickland" <crwlr@verizon.net> wrote
    >>> "cosmo" <nothing@nowhere.com> wrote
    >>>>I posted earlier about my 325 with 145k miles that knocks for the
    >>>> first few minutes until it comes up to temp.
    >>>> Well, adjusting the valves didn't help any. They were fine except for
    >>>> two that might have been slightly loose by .01" or so.
    >>>> Could it be that one of the many sensors that control timing is
    >>>> defective? Maybe they kick out after they've done their job at cold
    >>>> start and the engine runs right after that.
    >>>
    >>> Your car uses HYDRAULIC valve lifters.

    >>
    >> Jeff, you're completely off on this. If you go back and actually
    >> READ the previous thread, you would discover that this is an
    >> '88 325i with M20 engine, which does not have hydraulic tappets.
    >>

    >
    >
    > Well, except for that tiny problem, my explanation is good ...
    >
    > I find it odd that there are no lifters though.
    >


    Umm, didn't Floyd say no hydraulic tappets? That generally means the valves
    are actuated by solid (mechanical) lifters, unless it's a rotary or 2 stroke
    motor.

    Tom K.



  8. #8
    Michael Yeager
    Guest

    Default Re: 325 still knocking after valve adjustment,..

    The M20 motor has a rocker arm that rides the cam and directly opens
    the valve when the cam lobe rises. There are no lifters of any sort in
    these motors. If the adjustment on the eccentric (on the valve end of
    the rocker arm) is too far out, they will "tick" and that may be loud
    enough to be annoying. If you have a knock, that is an issue that an
    experienced (read "shadetree") mechanic can isolate with an old wooden
    handled screwdriver. There are other, perhaps more accurate, ways to
    do it but I've learned the old guys do it best with what they had back
    when. Find an older guy with a nice street rod from before you were
    born and he'll be able to tell you what's going on.

    On Tue, 18 Dec 2007 19:51:23 GMT, "Jeff Strickland"
    <crwlr@verizon.net> wrote:

    >
    >"Floyd Rogers" <fbloogyuds@hotmail.com> wrote in message
    >news:13mg3jmlrcl0dfd@corp.supernews.com...
    >> "Jeff Strickland" <crwlr@verizon.net> wrote
    >>> "cosmo" <nothing@nowhere.com> wrote
    >>>>I posted earlier about my 325 with 145k miles that knocks for the
    >>>> first few minutes until it comes up to temp.
    >>>> Well, adjusting the valves didn't help any. They were fine except for
    >>>> two that might have been slightly loose by .01" or so.
    >>>> Could it be that one of the many sensors that control timing is
    >>>> defective? Maybe they kick out after they've done their job at cold
    >>>> start and the engine runs right after that.
    >>>
    >>> Your car uses HYDRAULIC valve lifters.

    >>
    >> Jeff, you're completely off on this. If you go back and actually
    >> READ the previous thread, you would discover that this is an
    >> '88 325i with M20 engine, which does not have hydraulic tappets.
    >>

    >
    >
    >Well, except for that tiny problem, my explanation is good ...
    >
    >I find it odd that there are no lifters though.
    >


  9. #9
    Jeff Strickland
    Guest

    Default Re: 325 still knocking after valve adjustment,..

    Well, in that case if there is still a tapping then either the tapping is
    not the rockers OR the rockers are still out of adjustment.

    I haven't seen the inside of an M20, but I was thinking that pretty much all
    motors used a hydraulic tappet or lifter in the valve train somewhere. I've
    owned old cars and trucks that did not have hydraulic lifters, so I get the
    idea. But, I just thought that engines came with hudraulic parts to avoid
    the noise that comes from valve lash. I guess I was wrong on this one ...



    "Michael Yeager" <myeager@nospam.cfl.rr.com> wrote in message
    news:glggm31ljqq1r1cto58dfi83gn1h29bp36@4ax.com...
    > The M20 motor has a rocker arm that rides the cam and directly opens
    > the valve when the cam lobe rises. There are no lifters of any sort in
    > these motors. If the adjustment on the eccentric (on the valve end of
    > the rocker arm) is too far out, they will "tick" and that may be loud
    > enough to be annoying. If you have a knock, that is an issue that an
    > experienced (read "shadetree") mechanic can isolate with an old wooden
    > handled screwdriver. There are other, perhaps more accurate, ways to
    > do it but I've learned the old guys do it best with what they had back
    > when. Find an older guy with a nice street rod from before you were
    > born and he'll be able to tell you what's going on.
    >
    > On Tue, 18 Dec 2007 19:51:23 GMT, "Jeff Strickland"
    > <crwlr@verizon.net> wrote:
    >
    >>
    >>"Floyd Rogers" <fbloogyuds@hotmail.com> wrote in message
    >>news:13mg3jmlrcl0dfd@corp.supernews.com...
    >>> "Jeff Strickland" <crwlr@verizon.net> wrote
    >>>> "cosmo" <nothing@nowhere.com> wrote
    >>>>>I posted earlier about my 325 with 145k miles that knocks for the
    >>>>> first few minutes until it comes up to temp.
    >>>>> Well, adjusting the valves didn't help any. They were fine except for
    >>>>> two that might have been slightly loose by .01" or so.
    >>>>> Could it be that one of the many sensors that control timing is
    >>>>> defective? Maybe they kick out after they've done their job at cold
    >>>>> start and the engine runs right after that.
    >>>>
    >>>> Your car uses HYDRAULIC valve lifters.
    >>>
    >>> Jeff, you're completely off on this. If you go back and actually
    >>> READ the previous thread, you would discover that this is an
    >>> '88 325i with M20 engine, which does not have hydraulic tappets.
    >>>

    >>
    >>
    >>Well, except for that tiny problem, my explanation is good ...
    >>
    >>I find it odd that there are no lifters though.
    >>



  10. #10
    R. Mark Clayton
    Guest

    Default Re: 325 still knocking after valve adjustment,..


    "Floyd Rogers" <fbloogyuds@hotmail.com> wrote in message
    news:13mg3jmlrcl0dfd@corp.supernews.com...
    > "Jeff Strickland" <crwlr@verizon.net> wrote
    >> "cosmo" <nothing@nowhere.com> wrote
    >>>I posted earlier about my 325 with 145k miles that knocks for the
    >>> first few minutes until it comes up to temp.
    >>> Well, adjusting the valves didn't help any. They were fine except for
    >>> two that might have been slightly loose by .01" or so.
    >>> Could it be that one of the many sensors that control timing is
    >>> defective? Maybe they kick out after they've done their job at cold
    >>> start and the engine runs right after that.

    >>
    >> Your car uses HYDRAULIC valve lifters.

    >
    > Jeff, you're completely off on this. If you go back and actually
    > READ the previous thread, you would discover that this is an
    > '88 325i with M20 engine, which does not have hydraulic tappets.
    >
    > FloydR
    >


    I was going to post the same as Jeff, however although big sixes in the
    1980's had hydraulic tappets, I was not sure about this model.



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