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Thread: Is this a cracked head?

  1. #1
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    Is this a cracked head?

    Hi,

    I replaced head gasket on vanos m50 (head machined and tested - passed).

    Coolant still breached the cylinders. Pulled off head today hoping I just dinged up the gasket or something, but I see this little crack. Is it enough? (see photo - ignore one of my beard hairs on the right side of the hole, look for the crack running up towards the valve)
    image1 (1).jpg
    Last edited by papapela; 02-17-2019 at 12:55 PM.

  2. #2
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    It is more than enough. Cracks get larger when the engine heats up. You should go back to the fellas who tested your head and get a refund.

  3. #3
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    Quote Originally Posted by Thomas525 View Post
    It is more than enough. Cracks get larger when the engine heats up. You should go back to the fellas who tested your head and get a refund.
    Okay. Will do. Hopefully they are understanding. Can that crack be repaired or do I replace?

  4. #4
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    you CAN get a crack welded shut, but that depends on the cost of welding vs. the cost of another head.
    Charlie

    Your mission, should you decide to accept it, is to add value to these threads, either by pictures or by descriptions, so the next person with the same or similar problem stands on your shoulders.

  5. #5
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    head crack M52 003.jpgcyl head TV leds 001.jpgYes, it is. That's #4, cracked exactly the same as mine is.
    I am kicking myself right now as being obsessed with flatness I looked right past this crack(so did my machinist)and had it resurfaced. After resurfacing and putting the cams back in I flipped it over and there she is flipping me the bird.
    I'll be consulting with the machinist tomorrow about possible solutions. The problem is .005" was removed and it will need resurfacing again after repair, .011" is max.
    Last edited by ross1; 02-19-2019 at 07:24 AM.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  6. #6
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    You mean a crack can be so shallow ? 0.005"? And it can be skimmed off ? I didn't know that. Would have been VERY helpful to have known that much earlier lol. Ah but I had two cracks then would probably not have worked.

    - - - Updated - - -

    Op if you pressure tested your cylinder head, then they owe you a refund for not catching the crack - no ifs and buts.

  7. #7
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    Quote Originally Posted by Thomas525 View Post
    You mean a crack can be so shallow ? 0.005"? And it can be skimmed off ? I didn't know that. Would have been VERY helpful to have known that much earlier lol. Ah but I had two cracks then would probably not have worked.

    - - - Updated - - -

    Op if you pressure tested your cylinder head, then they owe you a refund for not catching the crack - no ifs and buts.
    One thing I need to reiterate, I put the head back on without noticing the crack, drove it for 100 miles, parked it, pulled off the head then saw the crack. Could I have caused this cracked within the 100 miles I put on the car since I got it back from the machinist?

    It's a stupid question - I know the crack was there all along. The original gasket looked f$%#$ fine - but my dumbass was still dead set that "it must just need a new gasket".
    Last edited by papapela; 02-18-2019 at 10:19 PM.

  8. #8
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    Quote Originally Posted by Thomas525 View Post
    You mean a crack can be so shallow ? 0.005"? And it can be skimmed off ? I didn't know that. Would have been VERY helpful to have known that much earlier lol. Ah but I had two cracks then would probably not have worked.

    - - - Updated - - -

    .
    NO, the crack remains, photo didn't show it. New photo posted
    Last edited by ross1; 02-19-2019 at 07:25 AM.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  9. #9
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    That crack is not just on the surface. I'm certain that it goes through the entire thickness of the casting. A weld could stop the leakage but I wouldn't expect it to last forever. It will always be weak in that spot.

  10. #10
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    Mine was ground out, about a walnut sized hole, and welded but the crack opened further down in the bowl after cooling. Welder is speculating about hogging out the area with an end mill then rebuilding the entire the area with weld. Need to confer with the machinist too as there will be more for him to do.
    My welder is confident he can repair it given access for his torch, hence cutting away a large area. He does this sort of thing all the time to some very expensive castings, pressure vessels, etc. for decades and is confident.
    It is very disturbing to watch the process which is initially quite destructive. Pretty much like having a cavity in your tooth filled.

    - - - Updated - - -

    Quote Originally Posted by papapela View Post
    The original gasket looked f$%#$ fine - but my dumbass was still dead set that "it must just need a new gasket".
    Welcome to my world.
    https://www.bimmerforums.com/forum/s...your-instincts
    Last edited by ross1; 02-20-2019 at 07:22 AM.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  11. #11
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    Wow, you two are like soul brothers.
    I would get a refund and buy a head from ebay or junk yard to have rebuilt
    Last edited by Sleepyhead97; 02-20-2019 at 07:28 AM.

  12. #12
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    Ross1, I have just the place you can send your head and have it rebuilt. I had the same problem on my '94 525i back in 2011. I purchased a completely rebuild head with a 12 mos warranty, yes 12 mos, not 3 as many places offer. According to Peter the owner, it's because of the way he repairs them.....the correct manner without getting into specifics. He used to be a F1 machinist and specializing on BMW heads. You do need to send him your core though so hopefully you didn't mill it beyond .012

    BTW, I still own the 525i and haven't had one issue with this rebuilt head.......very impressive!

    http://www.autoheadperformance.com/

    Ask for Peter.....and Good Luck!

  13. #13
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    Quote Originally Posted by Thomas525 View Post
    You mean a crack can be so shallow ? 0.005"? And it can be skimmed off ? I didn't know that.
    No..

    I think the point is that after welding the head needs to be resurfaced again, and if their is enough free room left for another resurfacing..
    A welder can't just weld it perfectly flat. He has to weld it higher than the flat surface so it can then be machined flat.

    And you can't just resurface the one spot.. A proper resurfacing, no matter how deep or shallow, must skim the entire surface..
    E36 M3 S50 - E53 X5 M54 - 1980 Porsche 931 - 2001 Impreza RS25

  14. #14
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    Quote Originally Posted by ricks5series View Post
    Ross1, I have just the place you can send your head and have it rebuilt. I had the same problem on my '94 525i back in 2011. I purchased a completely rebuild head with a 12 mos warranty, yes 12 mos, not 3 as many places offer. According to Peter the owner, it's because of the way he repairs them.....the correct manner without getting into specifics. He used to be a F1 machinist and specializing on BMW heads. You do need to send him your core though so hopefully you didn't mill it beyond .012

    BTW, I still own the 525i and haven't had one issue with this rebuilt head.......very impressive!

    http://www.autoheadperformance.com/

    Ask for Peter.....and Good Luck!
    Thanks Rick,
    This looks like a very good resource. Were I not already "pregnant" with this head I'd be all over it.
    I've committed today to more work on my existing head (there is a joke here somewhere). If it fails pressure testing I'll have an alternative.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  15. #15
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    Well, crack grew after welding. welder says can be fixed but much more machine work.
    Moral of the story, if you see a crack start shopping for another head

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

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