freshening up a 1.9 - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• freshening up a 1.9 by spencebm on 17 Jul, 2014 10:22
• I need some guidance on what to have done at the machine shop when rebuilding a 1.9AAZ.  Here is what I have come up with.  Please add what you think should be looked at with your experience.  Thanks!
  
  block:
  
  new rings for pistons, check pistons
  new rod and main bearings with thrust bearing
  check crank-balance? polish?
  check/hone cylinder bores
  check block deck for flatness
  clean block
  
  head: (had about 70k miles when removed)
  
  check for flatness
  clean
  ??
  
• #1 by theman53 on 17 Jul, 2014 13:32
• I would first have the block and pistons looked at. See if there is taper and such. Then the rest can be done. If you need pistons usually the replacement pistons have the wrist pin cut in higher so if you deck the block .005" everything else stays the same. Just check to see what gasket you have now so you know if they cut too much deck you won't be out of spec for the 3 notch.
  
  If you tear into the head, I think it wise to do it all. For sure check to see how flat. If you pull the valves and think a couple need replaced then do all of them...and the guides and seals and etc.
• #2 by spencebm on 18 Jul, 2014 15:35
• great.  thanks. anyone else want to add anything?
• #3 by vanbcguy on 18 Jul, 2014 17:19
• Theman said exactly what I would have. :-)
• #4 by VW Smokr on 19 Jul, 2014 06:57
• While it's all apart & naked... a few other possible helps for longevity IMO:
  
  1) have rods checked for resizing/re-bushing (& new bolts?)
  2) get TDI crank gear & have machine shop modify your crank for the upgrade
  3) check intermediate shaft & bearings for condition & placement
  4) remove casting flash from intake tracts and the water pump flange & block inlet
  5) invest in head studs (some would add other studs also)
  
  Sounds like you want to do it right. Best wishes.
  
  J.R.
  SoCal
• #5 by TimpanogosSlim on 19 Jul, 2014 12:06
• I agree, everything with a bearing surface should be checked and polished by the machine shop. this is pretty standard procedure.
  
  Also, many machine shops are finding that operating an old school hot tank with oil based solvents while adhering to environmental and safety standards is an expensive proposition, so they have gone to a water based system. My machine shop is one of these, and they pressed the (wrecked anyway) IM shaft bearings out of the block strictly because the hot tank detergent damages bearing materials.
• #6 by RustyCaddy on 19 Jul, 2014 18:01
• Someone here, i think it was Tyler, suggested swapping out 7mm valves and guides with 8mm if you are planning on a lot of boost for your rebuild.
• #7 by xsp2467 on 20 Jul, 2014 08:31
• Magnaflux everything
• #8 by spencebm on 20 Jul, 2014 13:10
• Thanks for all the good advice!  Explain the magnaflux!
• #9 by vanbcguy on 20 Jul, 2014 17:17
• Magnaflux is a process where the block is covered in a metal powder and touched with a magnet. The field lines of the magnet will clearly show any cracks in the block even if they can't be seen with the naked eye.
• #10 by libbydiesel on 20 Jul, 2014 18:10
• Buff the pre-chambers until they are shiny and replace them if they have any of the tiny cracks that typically start at the opening of the insert.
• #11 by spencebm on 20 Jul, 2014 20:40
• thanks for the explanation and good advice.  I appreciate it. 
• #12 by ftm1776 on 21 Jul, 2014 07:00
• When I worked at Ford Motor Company in the 60s, we had a "wet" magnaflux rig. Wet the part to be check with special fluid and expose it to a strong magnetic field which caused any cracks to be shown as bright lines under a black light. I'm not sure if that is now an outdated method. It was a dream to have all of that gear to rebuild my old Bug !!!! And oh boy did I play !!!!
  
  QUESTION: Just for future reference..............How much money are you talking for all of this work??? Is it going to be mostly shop work or are you going to DIY some of it??
  
  Thanks
• #13 by 92EcoDiesel Jetta on 21 Jul, 2014 11:27
• Quote from: xsp2467 on 20 Jul, 2014 08:31

  Magnaflux everything
  

  
  Magnaflux won't work on aluminum so don't bother with the head.
• #14 by spencebm on 22 Jul, 2014 18:33
• I'm only having the minimum i can done by the machine shop.  I'm going to try to assemble everything myself.  what do you guys think the cost will be at the least?