Sno-Cat

I'm still researching for my first Audi A8.

Now, from what I know, 2007 + the 4.2 went to a timing chain and previous were timing belt.

Besides longevity/durability that come from a timing chain what are the real advantages of a timing belt?

And when a timing belt does break, is it ever the belt or usually something else, like a tensioner or pulley?

Now I'm strictly asking for the A8 4.2 D3.

I'm looking at an 05 L and 07 L belt and chain respectively.

mishar

Those two engines are quite different. 07 has more power and lower consumption as a result of 15 years of German engineering. I believe prices are quite different too. I don't see belt/chain as that important factor in making a decision.

Chain doesn't require any maintenance, but it is not unbreakable. Especially tensioners. If that happens engine has to come out in order to be repaired.

Timing belt should be replaced every 135,000 km (85,000 miles). That's $600 - $3600, DIY or a crazy dealer. If it brakes you need new valves, could be new pistons, or even a new engine.

I would always go for the newer one if I can afford it. It is not only engine.

Mister Bally

There are some perceived disadvantages to the FSI engines related to intake manifoldcarbonization that leads to poor fuel eCONomy and performance issues there are some recent threads with photos. Also note that for some reason, some Audi and VW engines have roller bearing issues with chain camshaft drive engines.

I hated having to replace the timing belt when my $20 thermostat stuck closed in the summer. The belt has to come off to get at the thermostat so I replaced it and the water pump and the rollers & tensioners etc.

Sno-Cat

Good to know Mishar! A local Audi dealer gave me an off the cuff quote of $1300. I know an independant VW/Audi shop that only deals with German stuff for $800. Not bad if the other costs stay down.

Mister Bally, which year are you referring to? I'm looking at 4.2 v8 only.

mikesd1980

Mister Bally have a 04 4.2L.

I have a 04 also. I got my timing belt service done for $2300 at the local stealership(2nd time done). The first time was a "VW/Audi specialist"($1300 parts and labor) with blauparts timing belt kit. The dealer did it the 2nd time about 6 months later(6k miles later). Dont know if it was blauparts fault or "the specialist". I just sucked it up, others have had good experience with blauparts though.

At 142k right now and engine and car still runs great!

mishar

What was wrong first time?

mikesd1980

I ordered the blauparts kit and went to "VW/Audi specialist in Va Beach to get it installed. He confirmed that he do the timing belt service at least once a week and he have been doing my oil changes for about a year so I felt comfortable. After 2 days of having the car, I picked it up and it was fine. About 3 months later I noticed antifreeze leaking(not alot) in my parking spot every morning. I was busy for the next 3 months than moved back to NJ. Thinking nothing of it I was just topping it off every 2 weeks or so. I thought it was the radiator. After I got settled in NJ I went to the local dealer. He told me water pump is leaking and showed me also. Serpentine belt looked really old too. So I just told the dealer to the whole job over. Also timing was off. After they changed everything the car ran perfect again.

Brozee

I <3 my non FSI engines. My 4.2L 05 with a belt has 110k on the clock and 40k on the belt. Never had an issue with that engine once, and paid $1200 for whole timing belt service (belt, serp belt, water pump, pulleys, etc.) The 6.0L W12 is chain driven but doesn't have an FSI engine so hardly any of the issues of carbon that the 5.2L V10 experiences or some of the 4.2L V8 FSI engines have (although the A8's V8 has barely any, compared to the RS4's crazy stupid problem of carbon, same engine).

I went with the blauparts kit and had the timing belt, pulleys etc installed from them. They sent me the wrong serpentine belt, so I never had that replaced, still on the same replacement that the owner before me had replaced due to a faulty thermostat at 40k; I bought the car at 50k. Did the timing belt service at 75k, and just preventative maintenance outside of it. I love the V8 in these cars, it's very nimble and punchy in the low end, even compared to the W12. Easy to really get on it and go when in a hurry. Recently chose the 4.2 V8 over my W12 to rush to an accident my girlfriend was recently in, the feeling of the V8 and nimbleness was advantageous in that situation over the W12.

Overall it's a non deciding factor for me. I would look at the other reliability gains you get from an 07+ (newer trunk latch, revised pieces all around the car with newer revisions.) But does it warrant the increase in price if you find a very nice condition 05-06? No, IMO. Definitely not.

Chain and belt both have no other advantages, Mister Bally, and a few other people found a few studies on the timing belt vs. chain, no real difference besides the replacement of the belt. But don't go thinking that with a chain your fine. Belt is in the front of the engine, and on the chain driven engines the chain is in the rear of the engine, so any issues and out comes the engine, although you'd never come across any. In some circumstances the teeth on the rings wear down or a guide that goes along the chain fails and has to be replaced. So overall a non factor. As for power and fuel economy difference I have noticed no such difference. I have experience driving my 05 A8 4.2 for the last 3 years, driving the W12 for the past few months, and drove a friends 08 A8 4.2, and a buddies S8 (little experience). So overall I've drove them all and haven't noticed a difference between FSI, non; belt, chain

Capiche?

Mister Bally

Sno-Cat; sorry for the typo, I meant FSI, not TDI. I edited my post.

Sno-Cat

No problem, Mister Bally.

Brozee, thanks for that write up. Timing chain at the rear and engine has to come out? Ya, that is bit more involved than that front end being removed.

I'm really keen on this 05 L for some reason even though it has 170,000 kms. Aside from fingernail scratched from the former real estate agent owner she (the car) feels really solid.

I've asked the dealer (who is selling) about the timing belt and getting all the typical timing belt kit stuff done to it included to the asking price. That I leaving knowing the car is good for that area for at least another 100,000 kms.