Catastrophic engine failure

[S2central.net]

Interesting fact on #3 bearing in that pressure loss scenario - even on the 20VT engines - or generalising to all the I5 donkeys ?

[220bhp]

The crank journal is clearly visible and is good conditon,no scoring or burn marks,I do not think it was oil starvastion,its a new oil pump and oil pressure was good.

[Pirvu Eugen]

Rod cap bolt failure? Just a thought!

[220bhp]

Rod cap bolt failure? Just a thought!
What would cause this sort of failure.

[Phil Payne]

What would cause this sort of failure.

Repeated messing about. They're a 'must change' item but few seem to bother.

[UrS4boy]

Repeated messing about. They're a 'must change' item but few seem to bother.

Not trying to contradict you Phil, but when I just checked the AAN Workshop manual, I find this confusing statement:

"Item 8: Only renew when engine is completely dismantled."

[220bhp]

Quote,
originaly posted by Phil Payne.repeated messing about.
Phil I appreciate your comments, but the caps have never been taken of in my ownership of this block. I bought it from allaudi several years ago,it came out of a low mileage s6 and the bores where perfect, {as they are now by the way}, so I did not take the caps of to check the bearings,as I saw no nead.
As it happens I agree with your comments and if I deside to changethe rodes or bearings I will be using new ARP bolts

[220bhp]

I have managed to strip the engine down to its componant parts and it would appear at the moment that Pirvu Eugen was right,rod bolt failure.I found The cap from the broken conrod and one broken bolt, plus bearing,the middle part of the rod was missing.
On close inspection you can see that the bolt had been cracked half way through for some time,as it is blackend you can see the other half is a clean break also the hole in the cap is clearly misshapen.I have taken some pictures but they wont load so I will try again later today.
Number three conrod is bent but I cannot see if this was through collateral damage.
or as I suspect the initial damage was done when the car had high boost problems, at the time it also cost me a brand new Turbo,as stated before when I replaced the turbo I took it to MRC for a remap and they could not get the car to make power,yet when it had high boost problems it had to much power,causing a new clutch to slip, so it seems logical to me.but I am no expert.

[prj]

What do you mean by "high boost problems"?
What did you have in the ECU of the car?

[220bhp]

It was diagnosed as a faulty non bosch map censor.

[prj]

It was diagnosed as a faulty non bosch map censor.

There are two safetys - MAP sensor based and MAF sensor based.
If one of the sensors fails the other safety should still work.
That is, unless it was turned off in your software.

If it was and you had 2+ bar boost without proper mapping, then that probably did the damage to the engine, maybe even a few rods were slightly bent before.

[Sir Buff]

Do you mean like it is in the software from ultimot? - No boost cut.

There are two safetys - MAP sensor based and MAF sensor based.
If one of the sensors fails the other safety should still work.
That is, unless it was turned off in your software.

If it was and you had 2+ bar boost without proper mapping, then that probably did the damage to the engine, maybe even a few rods were slightly bent before.

[Fat Audi 80]

A mildy bend rod would lead to a rod cap bolt failure over time i would think. Your statements about possible high boost instants must be the contributing factor here. We all know these engines are bullet proof unless they have been modified.

Cheers,

Steve

[prj]

A mildy bend rod would lead to a rod cap bolt failure over time i would think. Your statements about possible high boost instants must be the contributing factor here. We all know these engines are bullet proof unless they have been modified.

Cheers,

Steve

Exactly my thoughts... I am thinking the rod got bent during the "high boost problem" and that lead to the eventual failure of the engine.
If this is the case, then the engine is on the concience of the person who was responsible for the software on the car before it went to MRC...

[220bhp]

Steve, I could'nt agree more about these engines,which is why I thought it was safe to up grade to RS2 and no more.on checking the condition of the rest of the engine,the bores where absolutly perfect,nos 1,2 and 5 big end shells where unmarked,no 3 with the bent rod was not good but still intact, pistons and rings all checked out first class on no 1,2,AND 5.The top of piston 3 was still in the bore,infact when the engine blew I Pulled over straight away and the engine was still running. Looking back it would have been a scary moment loseing power assistance in traffic.
Still scary I have to say.