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Engine Specific Info and Questions => IDI Engine => Topic started by: andysimpson on April 15, 2007, 12:21:48 pm

Title: Snapped main bearing bolts
Post by: andysimpson on April 15, 2007, 12:21:48 pm

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.

Title: Snapped main bearing bolts
Post by: Wingaman on April 15, 2007, 12:45:45 pm

It's the first time I heard this  :shock:

Title: Snapped main bearing bolts
Post by: Audi80 on April 15, 2007, 12:58:40 pm

Does this look familiar?

Kilck (http://www.kotinet.com/matti.farm/Kuva004.jpg)

Title: Snapped main bearing bolts
Post by: Wingaman on April 15, 2007, 01:00:37 pm

Holy***  :shock:

Title: Snapped main bearing bolts
Post by: andysimpson on April 15, 2007, 01:07:50 pm

Quote from: Audi80

Does this look familiar?

Kilck (http://www.kotinet.com/matti.farm/Kuva004.jpg)

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.

Title: Snapped main bearing bolts
Post by: Audi80 on April 15, 2007, 01:23:24 pm

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 (http://www.kotinet.com/matti.farm/Audi/Moottori/118-1874_img.jpg)  :wink: Used 12.9 allen head bolts.

Title: Snapped main bearing bolts
Post by: andysimpson on April 15, 2007, 01:41:22 pm

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 (http://www.kotinet.com/matti.farm/Audi/Moottori/118-1874_img.jpg)  :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.

Title: Snapped main bearing bolts
Post by: 935racer on April 16, 2007, 03:21:11 pm

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...

Title: Snapped main bearing bolts
Post by: Audi80 on April 16, 2007, 10:56:14 pm

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: