Changed my serpentine belt and tensioner yesterday

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dparm

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Apr 19, 2010
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NEVER. AGAIN. Book time is supposedly 3.1 hours but it took me almost triple that in the garage with a full set of tools. Since my car has a huge engine shoe-horned in, it is quite involved: 1. Remove intake 2. Remove headlamps 3. Remove bellypan 4. Remove driver's side wheel 5. Remove & drain washer fluid bottle 6. Remove entire front bumper (including headlamp washers, fog lamps) 7. Remove auxiliary radiator shrouds 8. Remove front radiator assembly (3 radiators) From there you have about 6 inches to reach down/up and remove the tensioner, idler roller, and belt. It took me almost 3 hours just to get everything disassembled. And of course, being a German car, it's all a combination of Torx, hex, and triple-square. With 65k on the clock a few things were rusted or seized. The belt itself was all of 5 minutes to do. Re-assembling took about an hour, but in all it was a 9+ hour ordeal. I also took the opportunity to swap the front motor mount for a stiffer polyurethane mount (adds about 90 seconds worth of work). Indy shop can do this stuff next time at $95/hr. Parts were only about $150 ($100 for the tensioner, $10 for the belt, $40 for the mount). The original belt with 65k was a bit stiff and brittle and had some stress cracks, but was probably still good for another few years. The tensioner, on the other hand, was totally seized and wouldn't pivot at all. Engine sounds a tad different now and the stiffer mount removed some of the slop when you shift hard; I can get back on the power much faster now. My hands and body are still sore....
 
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Engine bay pic, just to put it in perspective. 4.2L 40V V8 in a Passat chassis. Audi had to redesign many systems just to fit the engine...the timing chain was moved to the back, two auxiliary radiators were added, the alternator had to be water cooled, etc. Engineering marvel, but impossible to work on.
 
Strange that the tensioner was gone. We have several vehicles 10-20 years old on the original tensioners. Not blaming Audi, just seems strange to have seized at such a young age. Of course now that I say this, they'll all die in the next week.
 
The same engine in a A8 will be easier to work on because there is more room. A V8 engine in the S4 is impossible to work on without remove a lot of surrounding parts. The 4.3L V8 in the MB E-Class has some room to change serpentine belt and tensioner without remove anything else, but the same engine in a C-Class is another story.
 
Originally Posted By: cchase
Strange that the tensioner was gone. We have several vehicles 10-20 years old on the original tensioners. Not blaming Audi, just seems strange to have seized at such a young age. Of course now that I say this, they'll all die in the next week.
The tensioner is an unusual design, for sure. It was also revised a few years later since they were prone to fail and snap belts. And sometimes when the belt snapped, it would hit the main engine seal and cause a colossal oil leak. This is not the same motor as the A8/S8...it's a modified version for this engine bay. Also not the same as the RS4 or new S5 (those are the 32V direct inject variant). The whole ordeal did help me appreciate the crazy amount of engineering they did to fit this thing in.
 
That motor is packed in there!! Great job getting it done yourself though! It ain't easy fixing those cars.
 
Originally Posted By: GMBoy
Looks like the spark plugs are easy to do. smile
Negative, takes 60-90 minutes. Intake has to come out and you need to start moving coolant/power steering stuff. The coilpack wiring harness is very difficult to remove, too (not much room).
 
Makes me glad the household A6 has the boring but easily serviced 2.8. I'm in love with the aural pleasures of the 4.2 (and the 2.7), but am kind of horrified of what can happen with things go wrong.
 
Originally Posted By: dparm
Originally Posted By: GMBoy
Looks like the spark plugs are easy to do. smile
Negative, takes 60-90 minutes. Intake has to come out and you need to start moving coolant/power steering stuff. The coilpack wiring harness is very difficult to remove, too (not much room).
Not that bad: http://forums.audiworld.com/showthread.php?t=2576874
 
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The part with the vice grip and T25...takes a while. First timers can expect an hour or more to change the plugs. I've done it a few times now and it takes me about 30. Projects like these make me want a lift or a service "pit" in my house.
 
You were lucky, you did not have to disconnect A/C system! Some VW/Audi need to drain the radiator coolant and discharge the A/C system to replace the drive belts. - Vikas
 
Really? Which ones. All Audi/VW with tight front clearances ive worked on are able to be put into a "service" position in which entire front assembly including radiator/condenser can be slid forward about two inches to give more room in belt area. Some you do need to discharge like you said to do the TIMING BELT, but setting to carrier service position gives plenty of room for serpentine belt.
 
Car salesman think I am nuts asking to look under the hood when car shopping (some can't even get it open!). Car serviceability/accessibility and quality of FSM does affect my buying decision.
 
Engineering marvel?? I'd call that an engineering cluster-[censored]. The belt tensioners on both my Accord and my Lumina each take about 20 minutes to replace (taking my time). I'll never understand the hoopla surrounding 'German engineering'. Sure, those guys can build a awesome, fiendishly complex machines. But it's often at the expense of serviceability and practicality... and when (even relatively simple) problems come up it can take them a decade to come up with a fix. I'm speaking mainly from my experience with Mercedes heavy truck engines. I AM impressed in some ways- but not with their priorities or their practicality.
 
My father worked at Bosch for 25 years. What you're describing, according to him, is a cultural thing. Germans typically don't like working on their own cars and often refuse to do it even for simple things. Hence, Audi doesn't "need" to design the cars to be easy for the average joe to work on.
 
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