Camshat cap snapped! Help! | FerrariChat

Camshat cap snapped! Help!

Discussion in '308/328' started by Pero, Aug 9, 2013.

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  1. Pero

    Pero Formula Junior

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    Yes, just like that. Urgently need a new one. It is a 102540 cap. Do you have an old spare one in your garage please let me know.

    /Pero

    Camshaft cap....
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    Last edited by a moderator: Sep 7, 2017
    Pero, Aug 9, 2013
    #1
  2. don_xvi

    don_xvi F1 Rookie

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    How?
     
    don_xvi, Aug 9, 2013
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  3. arthur bishop

    arthur bishop Karting

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    that's a very odd failure indeed. hopefully you know how it broke, perhaps an asymmetric load from tightening it improperly? as the caps are machined in situ during assembly, you'll need to run a camshaft reamer through all the journals to make sure the replacement is a good fit. otherwise you run the risk of the cam seizing and it happening again. be careful and good luck.
     
    arthur bishop, Aug 9, 2013
    #3
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ Lifetime Rossa

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    Most likely, it was cracked by overtightening when the "matchbook method" was used to act as a cam rotational lock. Line-reamed after assembly to the cylinder head as Authur indicated -- so, if you get a replacement, ensure the cylindricity of the new half to the existing cam bearing bore is reasonable-ish.
     
    Steve Magnusson, Aug 9, 2013
    #4
  5. arthur bishop

    arthur bishop Karting

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    steve, surely locking the cams that way (with no disrespect to the original poster if that's what they did) is a somewhat silly thing to do? im not familiar with the 308 engine but locking any cam that way doesn't seem right. with our 30 liter marine diesels we'd never think of doing that let along something that looks like a model sitting beside it.
     
    arthur bishop, Aug 9, 2013
    #5
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ Lifetime Rossa

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    I'd characterize it more as a "dangerous" or "skill needed" method -- can be done, but also easy to break the die-cast cap if you use the wrong thickness/shape compression shim and over-tighten (and a single paper match down the middle is the worst choice).
     
    Steve Magnusson, Aug 9, 2013
    #6
  7. arthur bishop

    arthur bishop Karting

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    thanks for the clarifcation steve. what wrong with locking the cams by using an old belt, say run through an oil filter remover that allows you to keep tension on the unit? i dont suppose the camshafts have a flat on them do they as that would be the best way?
     
    arthur bishop, Aug 9, 2013
    #7
  8. Pero

    Pero Formula Junior

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    I know it means big trouble. I have a very good machine shop that will have to take care of this if I can find a cap. Could be the wrong cap as pointed out by Crowndog. Have ordered 106836 from Eurospares to see if it is correct.

    /Pero
     
    Last edited: Aug 9, 2013
    Pero, Aug 9, 2013
    #8
  9. Pero

    Pero Formula Junior

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    I was torquing the bolts for the camshaft pulleys and had done three cams with the "paper under the cap" method. Everything went well. Well until the last camshaft. Unbolted a cap, put a paper under it and then it just snapped when torquing. That was a really bad moment.

    I started looking for the same cap but found out that it is very very NLA. I tried all sources I know of but with same result. Had some mail conversation with Eurospares with the same bad result. Totally NLA. Asked if the had some used parts that I could buy, no luck. I needed a cap so I ordered another one, 106836, just to get something to work on, well since 102540 doesn't exist on planet earth.

    The big surprise came a week later when the delivery from Eurospares arrived. The ordered 106836 are not marked with that number, they are marked 102540!!! I got the right ones!

    Talked to my mechanic, world class, and he pointed out that the one that broke had two colors on the broken surface. One more gray and the other silver white. Conclusion, there was a zone of weakness or a small crack in the cap. Look at top cap part in the picture.

    Putting the cap on?? You have to adjust the new ones to the camshaft since they are just "raw" cap material when you buy them. Normally you do in line boring with the camshaft off. A lot of work. For me it meant taking the cylinder head off again. His suggestion was to make a try with the cam in situ. We (well he) took some measures, took the new caps, I bought two just in case, and disappeared for a week. Came back today and had the two caps ready for assembling. He had bored/grinded the cap for a tight fit. We put it back and moved the camshaft a little back and forth. Removed it and he used a knife like tool to very carefully remove spots on the cap that were shiny, had contact. This was repeated several times, removing extremely little material at a time.

    Finally, the cap was back in place. I am extremely happy.

    /Pero
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    Last edited by a moderator: Sep 7, 2017
    Pero, Aug 27, 2013
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  10. dino_bob

    dino_bob Karting

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    Did you inspect them before mounting them? I would guess that the dark area was already broken before you tightened it, and that you only broke the white area.
     
    dino_bob, Aug 27, 2013
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  11. Pero

    Pero Formula Junior

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    Couldn't see anything strange on them before. We aspect the same thing as you do, there was an old damage to the cap. Anyway, from disaster to happy ending! This mechanic is brilliant!

    /Pero
     
    Pero, Aug 27, 2013
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  12. Crowndog

    Crowndog F1 Veteran

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    Very strange indeed with the part# s. Glad it worked out. Perhaps mention of this in the sticky thread xref is appropriate.
     
    Crowndog, Aug 27, 2013
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  13. Pero

    Pero Formula Junior

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    That is a good idea. Thank you for your help earlier.

    /Peter
     
    Pero, Aug 27, 2013
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  14. Sledge4.2

    Sledge4.2 F1 Rookie

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    When I first bought my 308 a mechanic installed one if the cam caps on rotated 180 degrees when doing the major.

    The car ran for 30 seconds, then the cams seized and bent valves.

    Be very careful
     
    Sledge4.2, Aug 28, 2013
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  15. Pero

    Pero Formula Junior

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    Oooohh, that hurts. I will check mine again. This guy adjusted it many times by scraping off a little material at a time. Looked correct, no contact when turning the camshaft.

    /Pero
     
    Pero, Aug 28, 2013
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  16. Sledge4.2

    Sledge4.2 F1 Rookie

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    i am sure if he is an expert mechanic, he is being obsessive about it, but just double check. Mine spun fine too, until ....
     
    Sledge4.2, Aug 28, 2013
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  17. Sledge4.2

    Sledge4.2 F1 Rookie

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    Sledge4.2, Aug 28, 2013
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  18. Pero

    Pero Formula Junior

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    Thank you!

    I have now double checked all caps and they are in the correct position. The number on the cap corresponds to the number on the cylinder head.

    Interesting thread. A really bad time for you. What I do not quite understand is how they could turn one of your caps 180 degree wrong? The cap is only numbered on one side, at least mine are, and the corresponding number is on the cylinder head. Only one place and one way to go. Well, stranger things have happened.

    /Pero
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    Last edited by a moderator: Sep 7, 2017
    Pero, Aug 31, 2013
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