repairing camshaft bearings? - page 1 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• repairing camshaft bearings? by truckinwagen on 28 May, 2010 19:34
• I just pulled the head of my new car apart to rebuild(and port) it, and found that the number one(closest to the timing belt) cam bearing surface, as well as the corresponding bearing surface of the cam, have been eaten. pretty bad...
  
  I have heard of cutting the bottom off the cap and then line boring, but the damage is too bad for that(I think)
  
  I have also heard of aftermarket bearing shells that can be installed after machining the head for them(like a rod bearing with two halves) but they are mythical, and I cant find them(I have seen pics of them, but never seen them for sale)
  
  anyone have any input? I would like to save the head, but dont want it to fail prematurely due to a poor fix...
  
  -Owen
• #1 by rallydiesel on 28 May, 2010 19:40
• Are you talking about an idi head? They don't have actual cam bearings, just the naked head casting. You could try getting ahold of a true BRM/BEW PD camshaft bearing and seeing if it has the same inside diameter as your camshaft and then getting that cam support align-bored to fit the bearing.
  
  Otherwise,  I think you should look for a new head.
• #2 by truckinwagen on 28 May, 2010 19:47
• yes it is an IDI head, and I am aware that they dont have separate bearings in the head for the cam, but there was an aftermarket company(at some point) that made a set to retrofit into the IDI head.
  
  does anyone know if the PD cams have the same diameter bearing surface?
  
  what about welding and then machining the bearing surface of the head? or would that ruin the temper of the bearing surface leading to premature failure again?
  
  -Owen
• #3 by Rabbit on Roids on 28 May, 2010 19:51
• ive cleaned up some pretty chewed up bearing surfaces before with just emery cloth. cam would not spin when i started, then when i was done, it spun like it were brand new. that engine is still on the road too...
• #4 by truckinwagen on 28 May, 2010 19:58
• this is pretty bad, nearly the whole surface is worn, as much as 1/32" and material from the head has stuck to the cam.
  
  I will try to get some pics of it and post.
  
  certainly needs drastic repairs, just not sure what would be the right one(if any)
  
  -Owen
• #5 by theman53 on 28 May, 2010 20:04
• I wouldn't worry about welding. Weld is stronger than the material that it was welded to, so you should be fine. I would go that route over finding a bearing as you will have to have it machined for the bearing anyway. good luck whatever you do.
• #6 by truckinwagen on 28 May, 2010 21:02
• I wasn't sure if they were heat treated to withstand wear better or not.
  
  looks like welding and machining will be my best bet, just need to see if there is a local shop that can do that for me or not...
  
  here are the pics:
  
  
  
  
• #7 by Dakotakid on 28 May, 2010 22:20
• Are you in the habit of running the belt too tight or revving the dog poop out of the engine before the oil starts moving or....what was the cause here? Swapping of cam cap?
• #8 by Baron VonZeppelin on 28 May, 2010 22:22
• Those parts are History to me man !
  
  The bore even looks out of round from amount of material gone.
  I wouldn't really trust the camshaft surface either on that journal.
  In the cams defense - it is hardened on journals and lobes - but ouch. That shet is damaged !
  
  If they were unobtanuim type things - the expense and proceedures to repair might be worthy. But you'll be in way deep fixing that stuff.
  
  I know Alaska isn't easiest place to get stuff - but there are some VW dieselers up there. California - washington - oregon sources might not be too extreme on shipping.
  
  Is it 1.6 12mm mechanical head ?
  
  
  Good luck for you
• #9 by truckinwagen on 28 May, 2010 23:24
• it is the head off the $400 euro golf I scored  few months back.
  
  I have no idea what its history is, or what caused the failure.
  and I had no intention of using the cam, just wondering what could be done about the head.
  
  I can say that the two nuts on the cap that was trashed were not tight, not loose, but not tight.
  
  all the rest of the bearing surfaces are perfect, and apart from a couple bent valves and busted lifters the head is perfect, not even any cracks between the valves!
  
  I do have a spare head in the works(if I can get a paycheck to myself), but it would be such a shame to give up on such a nice head without at least looking into fixing it.
  
  -Owen
• #10 by rabbid79 on 29 May, 2010 02:28
• If you do decide to have it welded, have it acid dipped first if that's what the welder thinks should be done.  And since it needs a line bore either way, try to get a hold of a new cam cap and save yourself the trouble of welding up the old one too.  Maybe as a test, your welder could try building up the old cam cap, just to determine the feasibility of welding this oil soaked aluminum.  (I know, it sounds like BS, but these heads are very porous.)  This way, at worst, the only thing that can get screwed up trying to fix anything is the old cam cap, which you would probably want to replace anyway.
• #11 by Rabbit on Roids on 29 May, 2010 06:47
• Quote from: rabbid79 on 29 May, 2010 02:28

  If you do decide to have it welded, have it acid dipped first if that's what the welder thinks should be done.  And since it needs a line bore either way, try to get a hold of a new cam cap and save yourself the trouble of welding up the old one too.  Maybe as a test, your welder could try building up the old cam cap, just to determine the feasibility of welding this oil soaked aluminum.  (I know, it sounds like BS, but these heads are very porous.)  This way, at worst, the only thing that can get screwed up trying to fix anything is the old cam cap, which you would probably want to replace anyway.
  

  
  aluminum is EXTREMELY pourous, and soaks up oil, grease, and other impurities like a sponge. then when you go to weld it, all the crap burns out of the metal, and makes for a sub-par weld. my dad is a very good welder, and if its too dirty, he wont even try welding it. its so hard to get aluminum clean again once its been contaminated.
• #12 by theman53 on 29 May, 2010 06:59
• I would still weld it. It isn't holding weight, just oil pressure and staying round. The black junk that floats to the top could be machined and rewelded and remachined if you are too concerned. I would put about a 1/4" bead all the way around and have them shave most all of it off again.
  Another option maybe...There is an amish repair shop that had an engine from the early 1900s. There were no more mains and rods available and nothing else would swap. He made his own babbit bearing out of lead and machined it to fit the crank and rods. Worked fine. The mold for the thing was ugly, but it got it done.
  FWIW these amish guys I find seem to do stuff the "old" way. Sometimes it is the only way and then it is practical to go to them
• #13 by Rabbit on Roids on 29 May, 2010 11:49
• where the hell are you gonna find an amish machine shop in alaska? lol...
• #14 by theman53 on 29 May, 2010 11:57
• True dat!
  
  Maybe eskimos have similar practices LOL