Sno-Cat

Here is a great video if you haven't seen it before. I'm sure there are short cuts, but this is doing it properly. So critical to inspect everything thoroughly.


I also wanted to add that my brother recently had his timing belt done on his 2007 VW diesel Jetta and it was over due. The old belt looked as new as the new one.

So what are the predominate failures related to the timing belt group (on the A8 4.2)?

mishar

Not really proper procedure. He didn't use special tool for timing alignment. This way pretension of the left roller is impossible so if belt is a bit different length timing will be that much off. Not a huge problem, but not a proper procedure either.

I think that timing belt would last as long as engine if there is not any leak in that area. Water pump and thermostat not that long. Unfortunately ingenious German engineers came with a design where thermostat can't be changed without removing timing belt and it is also powering water pump. Well, 15 years later they came with chain, but just to make it more complicated they put it at the back of the engine.

Sno-Cat

I've read about that tool for holding the timing, but have heard if you've done it enough times you don't need it But it is important to confirm with a shop that they do own and use them. Peace of mind for the customer.

Mister Bally

DISCLAIMER: I am a Audi demographic reject and a cheapskate. My opinions are just that, my opinions. follow them at your own peril. In previous threads, I have been flamed at for some of these opinions.....

The water pump bearing can fail and leak or the OEM thermostat fails in the closed position before the belt fails due to weakness in most, but not all circumstances.

This is why normal timing belt maintenance procedures include replacement of the water pump, thermostat as well as other moving parts (rollers & tensioners)
The recommended interval is 75,000 miles for timing belt replacement with these engines which I personally feel is too CONservative.

I go back to five of my older VW and Audi's with overhead cam engines that I have owned that had "replace when they break" timing belts. Of course, those were non-CONtact engines so you would "only" be stranded but the valves on the engine would not be ruined. There was an inspection procedure which was part of the maintenance procedures to look for cracking and, if detected, you were to replace the belt. I always replaced the belt whenever the water pump started to leak since I had the belt off anyway.

Those engines were higher revving and the belt was a lot shorter so I figured if I could go 185,000 miles before replacing one of those (and only because the water pump failed) I figured the belt on my A8 engine would be good for at least 150,000 miles. I inspected the belt and even posted photos here in the past and decided to wait. Again, I only replaced it because of a thermostat failure around 125,000 miles.

Yes, I was flamed here and scolded by posts such as: "If you drive an $80k car but cannot afford proper maintenance on it, you should not be driving this car". Actually, I paid half that buying mine off of a two year lease from a dealer in Chicagoland. Of course I replied that's how I am able to afford these overpriced sewing machines; by not spending money when unnecessary. I also am not keen when others tell me how to spend my money. I was also crowned "Miser Bally" as well. I wear that one with a badge of honor.

mishar

Not that simple. Camshaft gears can rotate freely when bolts are loosen. So The Tool holds camshafts and crankshaft in a position while you fit the timing belt. That process includes pretension of left tensioner. That part is not possible without that tool. Once the belt is in place you tight camshaft bolts and that's it. So it's not that shop has and use it. It's also that they now how to use it properly.

Mister Bally

I did not see the proper belt tensioning device used nor the guys measuring belt deflection. Maybe they have calibrated thumbs and eyeballs. The video also did not show recharging the refrigerant for the Air CONditioning system. A fun procedure. When I did mine I left the CONdensor attached. A few photos are in my gallery/album area.

Sno-Cat

Great info guys! Thanks!

Mister Bally, so look for the coolant leak before replacing belt?

I like the video because it shows the labour involved and how, on a hoist, it can be inspect properly. That is, instead of looking down at a 16" gap in "service position".

jandreas

The T40005 TOOL is $48.50 from Snap-On. I think I might've spent $100-130USD on all the tools required for the timing belt change. You can also buy the OE parts from several online audi dealers for about the same price as the aftermarket crap...

mishar

Some links would be greatly appreciated.

jandreas

Try Sunset Imports in Beaverton, Oregon (around cost + 15%). There is a dealer in Florida (Suncoast? -- I forget) that might do some parts @ cost+10% but you'll need to price shop.