OMG Timing belt broke on my 2004 A8, catastrofic damage-WTF
06-03-2015, 07:23 AM
#21
AudiWorld Senior Member
I went to look at a car that was for sale. The car was overdue for a belt service. I get a call from the owner the morning of the appt and the owner told me that the timing belt broke. Short story is that the owner tried to repair the motor but it never ran right again as a couple of pistons needed to be changed. Now one of the cylinders is scored. The engine is not worth repairing. Suffice to say, I didn't buy the car. Even if the timing belt didn't break, I would have had the car towed to my place so that the timing belt could be done.
06-03-2015, 12:41 PM
#22
AudiWorld Super User
Looks to have been the same root cause with this poor guy too.
https://www.audiworld.com/forums/a8-...-work-2882133/
Although he'd had the timing belt service done recently by Audi, but apparently not the hydraulic tensioner replaced. Sadly for this guy it seems a catalogue of errors then ensued resulting in a completely blown engine and a totaled car.
https://www.audiworld.com/forums/a8-...-work-2882133/
Although he'd had the timing belt service done recently by Audi, but apparently not the hydraulic tensioner replaced. Sadly for this guy it seems a catalogue of errors then ensued resulting in a completely blown engine and a totaled car.
06-03-2015, 02:07 PM
#23
AudiWorld Wiseguy
That was never determined. Only thing that was determined was a loose timing belt which for some reason everyone scoffed at, yet was diagnosed by a VW tech who no doubt pulled the codes and sees timing belts every day. Not a bunch of guys on the net speculating off third hand descriptions. The chain of events and misdiagnosis after that leading to the rod through the block is not really possible to confirm without knowing more, but lots of ways to make it fit.
06-03-2015, 10:47 PM
#24
AudiWorld Super User
That was never determined. Only thing that was determined was a loose timing belt which for some reason everyone scoffed at, yet was diagnosed by a VW tech who no doubt pulled the codes and sees timing belts every day. Not a bunch of guys on the net speculating off third hand descriptions. The chain of events and misdiagnosis after that leading to the rod through the block is not really possible to confirm without knowing more, but lots of ways to make it fit.
But! Audi dealer who killed it said that TB is OK. Besides that, belt is always loose few hours after the engine was shut off. On top of that, if it skipped few teeth it would bend at least four intake valves on one bank, but more likely eight of them on all cylinders. In both cases it would be absolutely impossible to start engine again because of luck of compression. Finally, to brake connecting road you need much much more than contact with a quite fragile valve. Hydraulic shock, for example, created by liquid in the compression chamber that can't be compressed. It could be coolant or fuel. If it was coolant leaking into cylinder it would blow off coolant reservoir cap an bubble there like crazy. Only way that coolant can get into cylinder is when engine is shut off, most certainly not while idling. If it was stuck injector fuel would accumulate fast since the flow is huge and there is no combustion. It would also create a lot of white smoke from the exhaust, which it did. This speculation is based on a personal experience with cracked block on a ship engine that had coolant leak and Audi A4 1.8T stuck injector (twice) that fortunately didn't have enough cylinders to idle and brake something.
07-18-2016, 06:55 AM
#25
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You are right about online speculating, but this forum is all about that.
But! Audi dealer who killed it said that TB is OK. Besides that, belt is always loose few hours after the engine was shut off. On top of that, if it skipped few teeth it would bend at least four intake valves on one bank, but more likely eight of them on all cylinders. In both cases it would be absolutely impossible to start engine again because of luck of compression. Finally, to brake connecting road you need much much more than contact with a quite fragile valve. Hydraulic shock, for example, created by liquid in the compression chamber that can't be compressed. It could be coolant or fuel. If it was coolant leaking into cylinder it would blow off coolant reservoir cap an bubble there like crazy. Only way that coolant can get into cylinder is when engine is shut off, most certainly not while idling. If it was stuck injector fuel would accumulate fast since the flow is huge and there is no combustion. It would also create a lot of white smoke from the exhaust, which it did. This speculation is based on a personal experience with cracked block on a ship engine that had coolant leak and Audi A4 1.8T stuck injector (twice) that fortunately didn't have enough cylinders to idle and brake something.
But! Audi dealer who killed it said that TB is OK. Besides that, belt is always loose few hours after the engine was shut off. On top of that, if it skipped few teeth it would bend at least four intake valves on one bank, but more likely eight of them on all cylinders. In both cases it would be absolutely impossible to start engine again because of luck of compression. Finally, to brake connecting road you need much much more than contact with a quite fragile valve. Hydraulic shock, for example, created by liquid in the compression chamber that can't be compressed. It could be coolant or fuel. If it was coolant leaking into cylinder it would blow off coolant reservoir cap an bubble there like crazy. Only way that coolant can get into cylinder is when engine is shut off, most certainly not while idling. If it was stuck injector fuel would accumulate fast since the flow is huge and there is no combustion. It would also create a lot of white smoke from the exhaust, which it did. This speculation is based on a personal experience with cracked block on a ship engine that had coolant leak and Audi A4 1.8T stuck injector (twice) that fortunately didn't have enough cylinders to idle and brake something.
07-18-2016, 09:41 AM
#26
AudiWorld Senior Member
I think the take-away from all this is Audi isn't kidding when they say to change the belt every 75,000 miles. Now you could get a newer A8 that has timing chains, but then you have to deal with carbon cleaning and possibly chain guides when they wear out. To replace chain guides, the engine has to be pulled.
If you are lucky all you need are some used heads. If the pistons have been damaged, then it is time for another engine.
This is nothing new. Audi has been doing interference engines since the early 1990s.
If you are lucky all you need are some used heads. If the pistons have been damaged, then it is time for another engine.
This is nothing new. Audi has been doing interference engines since the early 1990s.
07-18-2016, 10:51 AM
#27
AudiWorld Super User
I think he "left the building" somewhere between 1 and 8 years ago...
Carbon cleaning to me remains mostly a province of non-A8 4.2's like the S4 of the era, and to some extent the V10 S8/S6 with deep sixed 3.2 still ground zero. Also dependent on exactly how the oil vapor/PCV related system is set up. Board not really hopping with those posts in the intervening 8 years. A few guide related posts. I survived the W12 chains--on a port motor "tweener" without a scratch, including many on my knuckles from 2.8 and 4.2 prior belt jobs that I do not miss. Not losing a lot of sleep on the Q5 or D4 S8 either, but if it happens it happens, plus I'm back under warranty now.
Carbon cleaning to me remains mostly a province of non-A8 4.2's like the S4 of the era, and to some extent the V10 S8/S6 with deep sixed 3.2 still ground zero. Also dependent on exactly how the oil vapor/PCV related system is set up. Board not really hopping with those posts in the intervening 8 years. A few guide related posts. I survived the W12 chains--on a port motor "tweener" without a scratch, including many on my knuckles from 2.8 and 4.2 prior belt jobs that I do not miss. Not losing a lot of sleep on the Q5 or D4 S8 either, but if it happens it happens, plus I'm back under warranty now.
Last edited by MP4.2+6.0; 07-18-2016 at 10:53 AM.
