The postmortem

Post by **andysimpson** » 02 Apr 2007, 18:20

Had a look today at what went wrong on the way to coney farm. A main bearing bolt has snapped causing a main bearing cap to splitt from where it has been flexing, main bearing cap has then had a fight with a conrod and the sump, conclusion is engine is 100% dead.

R.I.P. AAZ 432412

Post by **airhead** » 02 Apr 2007, 18:32

Sh!t buzz!

So it did actually throw a leg out of bed then?

Post by **HarryMann** » 02 Apr 2007, 18:48

but not a rod! That's two we've seen that have had main bearing cap breakages, through whatever reason...

RIP, now for the sequel

Post by **andysimpson** » 02 Apr 2007, 19:08

HarryMann wrote:but not a rod! That's two we've seen that have had main bearing cap breakages, through whatever reason...

RIP, now for the sequel

Have been looking into this further seems vw know about it, the bolts were longer from 95 onwards, what else changed at the same time????

No rods out but 1 must be badly damaged.

With pete's dads its hard to say what went first the cap or the bolt but with mine its very obvisous it was the bolt that caused it. The cap snapped on the meaty bit not the thin bit around the bolt.

Post by **HarryMann** » 02 Apr 2007, 19:17

Well, is that not near the end of the AAZ production run maybe... the TDi's don't do it - do they? Just wondering if the caps themselves were modified as well, to put less flexing loads on the bolts, in an inverse kind of way

Sorry Russel, we've hijacked your sorry thread

Post by **andysimpson** » 02 Apr 2007, 19:40

HarryMann wrote:Well, is that not near the end of the AAZ production run maybe... the TDi's don't do it - do they? Just wondering if the caps themselves were modified as well, to put less flexing loads on the bolts, in an inverse kind of way

Sorry Russel, we've hijacked your sorry thread

The last engine number i can find listed is 742885 the bolts were different from 560001 so there are a few with the different bolts about. Also noticed on the early engines its listed both the bolts for AAZ maybe yet another parts catalogue mistake or maybe you have to measure old ones. All the tdi's even the early ones list the late AAZ bolts.

Clive could you please measure one of the bolts on yours when you get chance too see if it is a problem with the 65mm ones.

I think the caps could of been modifed but as there not listed as a spare its hard to tell, will be interesting to compare how they look compared to the ones on the new engine.

Post by **Russel** » 02 Apr 2007, 20:13

These bolts should also only be used once.

Post by **andysimpson** » 02 Apr 2007, 20:24

Russel at Syncro-Nutz wrote:These bolts should also only be used once.

I agree, but as far as i know they have never been touched on mine, certainly not whilst i have had it.

Post by **HarryMann** » 02 Apr 2007, 23:08

I think the caps could of been modifed but as there not listed as a spare its hard to tell, will be interesting to compare how they look compared to the ones on the new engine.

Good suss, that will tell, going to glass-case it and mantlepiece it then Andy ?

I took a couple of main caps off my ADG to check the shells when I first got it, and bolted it back up... the top-end cracked (badly) but the bottom never gave trouble, despite many sessions of serious oil-burning detonation - but they'll be changed before it runs again

Post by **airhead** » 03 Apr 2007, 00:15

Sorry to interject, but Im assuming the caps are the semi-circular pieces that basically complete the circle of the big end by bolting around the cranckshaft onto the bottom of the conrod, and the shells are the thin pieces of metal that sit in between the conrod and cap and the crankshaft, am I right? Not always sure of the terminology, you know?

Post by **HarryMann** » 03 Apr 2007, 01:23

Yes, but we're talking main bearings here, those that support the crankshaft in its rotation rather than the crankshaft/con-rod journals (known as big-ends!)..

and yes, it is surprising that the loads on a nominally rotating assembly get so high, but then it directly reacts the forces from the pistons rods when pistons are at TDC and BDC - most of these are inertial - that is, the slowing down and speeding up of the pistons and rods as they reach the extremes of their travel - and these inertial forces go up rapidly with engine speed to significantly exceed the pressure forces on the pistons above maybe 3000 rpm. In a diesel the combination of pressure Vs inertial forces is significantly different than in a petrol (less pressure, more inertia in a petrol and vice versa)

Post by **airhead** » 03 Apr 2007, 16:53

Ah I get you now. Thanks for enlightening me on that!

Post by **syncropete** » 03 Apr 2007, 19:29

Vw never intended the vans to have an in line 4 golf engine laying on its side, it just so happens that they had some in stock !
Vw could have taken waterboxers into the next century with overhead cams, simplified cooling and lots of power, but they didnt.
Luckily the Japs did.

Sorry, couldnt help it.
seriously - Good luck with the motor.

Post by **airhead** » 03 Apr 2007, 21:16

Well if they wanted simplified cooling, they could have just kept with Aircooled engines, which they seemed to be better at to be honest. And for all the crapping on people do about them being expensive to make and not environmentally friendly, a replacement JX diesel engine is a lot more expensive than a 1600 twinport Type 1 engine! And Im sure with modern fuel injection and all that, they would be environmentally friendly now and belt out the power.

Post by **andysimpson** » 03 Apr 2007, 21:39

airhead wrote:Well if they wanted simplified cooling, they could have just kept with Aircooled engines, which they seemed to be better at to be honest. And for all the crapping on people do about them being expensive to make and not environmentally friendly, a replacement JX diesel engine is a lot more expensive than a 1600 twinport Type 1 engine! And Im sure with modern fuel injection and all that, they would be environmentally friendly now and belt out the power.

I have a late injected type 1, they are a massive improvement over the older ones but they still have bads points, undercooling it can take a good hour at 80mph on a cold day to get upto temp and as soon as you slow down it cools down. They still pi$$ oil everywhere when cold. A new type 1 injection engine is the same price as a new AAZ, i know which i would sooner have.