Snapped main bearing bolts - IDI Engine - VWDiesel.net The IDI, TDI, and mTDI source.

• Snapped main bearing bolts by andysimpson on 15 Apr, 2007 15:21
• My AAZ has broken 2 of its main bearing bolts resulting in a totallt dead engine. Its an early AAZ with the short bolts, i have a replacement engine with the long bolts, i assumed the long bolts were because the main bearing caps had been modified which they have not. I know of another AAZ which has done a similar thing are there any others out there?
  
  Does anyone know of an uprated bolt or cause?
  
  The other one was standard as far as i know, mine is very modified in a vanagon syncro so working hard.
  
  I just don't want a repeat of this.
• #1 by Wingaman on 15 Apr, 2007 15:45
• It's the first time I heard this  :shock:
• #2 by Audi80 on 15 Apr, 2007 15:58
• Does this look familiar?
  
  Kilck
• #3 by Wingaman on 15 Apr, 2007 16:00
• Holy***  :shock:
• #4 by andysimpson on 15 Apr, 2007 16:07
• Quote from: Audi80

  Does this look familiar?
  
  Kilck

  
  
  Yes just like that and then broken bits had a fight with a piston and con rod. Do you know what year engine was or the number the bolts chnaged at 560001 early 94. Mine had a different bolt, your has a shoulder mine was fully threaded. Engine standard or modified?
  
  How many more??
  
  Have looked at the ARP catalogue but can only find early main bolts listed (65mm ones) i need the 80mm ones.
• #5 by Audi80 on 15 Apr, 2007 16:23
• It was 5 cylider 2,4D with 80mm bolts (5 cylinder aaz) It was a little modified,  but not much ~140whp. No more cracked caps: pic  :wink: Used 12.9 allen head bolts.
• #6 by andysimpson on 15 Apr, 2007 16:41
• Quote from: Audi80

  It was 5 cylider 2,4D with 80mm bolts (5 cylinder aaz) It was a little modified,  but not much ~140whp. No more cracked caps: pic  :wink: Used 12.9 allen head bolts.

  
  
  Just looked up the part number for the 5 pot bolts its the same as the late AAZ's. I have been thinking about 12.9 bolts, there 10.9 standard. I have also thought about braces under the caps, will have a look tommorow if there is room.
• #7 by 935racer on 16 Apr, 2007 18:21
• Good grief what are you guys doing to these things? :shock:  I've never had any main cap or bolts failure issues one these things.
  
  Now crank sprocket/nose failure and the mains being round after such a failure is another story...
• #8 by Audi80 on 17 Apr, 2007 01:56
• I´ve heard of many cases, it´s not that rare :? Can´t say what causes it, but that 2,4 did have broken piston (between rings) and that cracked main cap. Luckily nothing else did broke.
  
  When I started to build my 1,6, the reinforcement bar was the first thing my machinist told me to do :roll: