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Thread: Valves not closing all the way after cylinder head rebuild

  1. #1
    Join Date
    Jan 2018
    Location
    Austin, TX
    Posts
    1
    My Cars
    1996 BMW 328i Convertibl

    Valves not closing all the way after cylinder head rebuild

    I am in the process of rebuilding the top end of the M52 engine in my 1996 328i to fix a leaking head gasket problem.

    I took the head off and sent it to a reputable shop in town to have it rebuilt and tested. They leveled the deck, replaced the valve guides, ground the valves and seats, pressure tested it, etc.

    I removed the cams, lifters and trays before taking the head to be rebuilt and, unfortunately, I neglected to label the position of each lifter. So, when I reinstalled the cams, lifters and trays, there was no way to know which lifters went were. I realize that they are all the same part, but several posts I have read stated it is always better to put them back where they came from when possible. I will know better next time.

    Onto the problem I need help with - Now that they cams and lifters are installed (using a good amount of assembly lube), I have turned the cams several times (using a 24mm wrench on the center of the cam) to ensure they are moving freely and that the valves are all opening and closing as they should. However, when I do this I notice a couple of the valves are not closing all the way when the cam lobes are up (see attached images). I also notice the some of those valves are opened a different amount (from the valve next it) when the cam lobes are down. I have taken the cams back out and checked the lifters and everything appears to be fine. I even rebuilt a couple of the lifters to ensure nothing was stuck inside them.

    I also confirmed that the valves are closing all the way when I removed the cams to check the lifters, so I am pretty sure it is not a problems with the valves, guides, seats or springs.

    So, is this normal behavior for cold lifters in a newly rebuilt head?

    Will they settle in once the engine starts?

    Is there a risk of the valves striking the top of the pistons if they don't settle in fast enough?

    Sorry if these are lame questions, but this is my first time rebuilding the top end on a BMW and I really don't want to damage the engine after spending all of this time and money.

    BTW, I was very careful using the "only cylinder 1 open" method for removing and reinstalling the cams, so I don't think there is any damage to the cams.

    Thanks in advance for any help/advice.

    - - - Updated - - -

    BTW, I pointed a light source into the port behind the problematic valves to better illustrate the problem openings. That is why there is a halo of light in the "almost closed" pictures.
    Attached Images Attached Images

  2. #2
    Join Date
    Feb 2005
    Location
    Joppa, Md
    Posts
    2,553
    My Cars
    99 M Coupe,04 K1200rs
    Quote Originally Posted by sharp1017 View Post
    I am in the process of rebuilding the top end of the M52 engine in my 1996 328i to fix a leaking head gasket problem.

    I took the head off and sent it to a reputable shop in town to have it rebuilt and tested. They leveled the deck, replaced the valve guides, ground the valves and seats, pressure tested it, etc.

    I removed the cams, lifters and trays before taking the head to be rebuilt and, unfortunately, I neglected to label the position of each lifter. So, when I reinstalled the cams, lifters and trays, there was no way to know which lifters went were. I realize that they are all the same part, but several posts I have read stated it is always better to put them back where they came from when possible. I will know better next time.

    Onto the problem I need help with - Now that they cams and lifters are installed (using a good amount of assembly lube), I have turned the cams several times (using a 24mm wrench on the center of the cam) to ensure they are moving freely and that the valves are all opening and closing as they should. However, when I do this I notice a couple of the valves are not closing all the way when the cam lobes are up (see attached images). I also notice the some of those valves are opened a different amount (from the valve next it) when the cam lobes are down. I have taken the cams back out and checked the lifters and everything appears to be fine. I even rebuilt a couple of the lifters to ensure nothing was stuck inside them.

    I also confirmed that the valves are closing all the way when I removed the cams to check the lifters, so I am pretty sure it is not a problems with the valves, guides, seats or springs.

    So, is this normal behavior for cold lifters in a newly rebuilt head?

    Will they settle in once the engine starts?

    Is there a risk of the valves striking the top of the pistons if they don't settle in fast enough?

    Sorry if these are lame questions, but this is my first time rebuilding the top end on a BMW and I really don't want to damage the engine after spending all of this time and money.

    BTW, I was very careful using the "only cylinder 1 open" method for removing and reinstalling the cams, so I don't think there is any damage to the cams.

    Thanks in advance for any help/advice.

    - - - Updated - - -

    BTW, I pointed a light source into the port behind the problematic valves to better illustrate the problem openings. That is why there is a halo of light in the "almost closed" pictures.

    I would think the clearance was closed by the valve grinding procedure, and when started, the lifter/tappets should pump up and make it worse?

  3. #3
    Join Date
    May 2017
    Location
    Owings, Md
    Posts
    1,105
    My Cars
    1998 328i
    Sounds like either a lifter is pumped up and not compressing back down or it is stuck in the bore of the cam ledge. There is guidance in the Bentley manual on how long to wait before fully tightening the cam caps depending on the temperature as the viscosity of the oil impacts the time correct the lifters to bleed down.

    Take the cams and that ledge back off of the head and feel how well that lifter slides in that bore. It may not have been clean enough when putting them together or it may be wear in the ledge causing them to get stuck and not let the valve close which would certainly catastrophic if the valve gets stuck fully extended and is hit by the piston. A new set of aftermarket lifters may be the easiest fix, OEM lifters would cost a fortune. I bought a new set of knock offs from ebay that were well rated but I haven't run them yet. Some people have disassembled lifters and cleaned them out. I gave up on this after trying to take one apart.

  4. #4
    Join Date
    May 2017
    Location
    Owings, Md
    Posts
    1,105
    My Cars
    1998 328i
    Engine building purists will tell you to never mix lifters because the cam lobes and the top of each lifter wear in together and the cam will be wiped out. I have not heard of it happening with these engines, I think dirty oil and clogged lifters is the far more likely risk and leave you with tapping valves, not the end of the world but really annoying after putting that much work into the engine.

  5. #5
    Join Date
    Jun 2002
    Location
    Aberdeen, NC (yes, again)
    Posts
    23,672
    My Cars
    E39M5, E500 4WD
    If the valves won't close when the cam lobes are not pressing on them, I would recommend against assembling that engine.

    You oiled the lifters? Really, I'm one of those "purists" who would not put a used lifter against a different lobe of a used cam, or in a different slot in the cam tray.

    Certainly, you can try rotating the cams several times, with lots of oil present, to see whether everything frees up and the valves seat properly.

    Chris Powell
    Racer and Instructor since, well. decades, ok?
    Master Auto Tech, owner of German Motors of Aberdeen
    BMWCCA 274412
    German Motors is hiring ! https://www.bimmerforums.com/forum/s...1#post30831471

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