Chain Stretching Question

[PRY4SNO]

I have a friend who's a journeyman mechanic with VW and says he's replaced a dozen or more 07k accessory/timing chains, under OEM warranty, because they stretch.

What kind of reliability issues would one encounter with this on a proportional basis... obviously for a right-ways swap into an old chassis and for a modded platform (IE a big turbo)?

Only asking for posterity but I DO eventually want to go this route for a gutted/caged Cq or 90sedan down the road.

What are the options... aftermarket chain? Upgraded (billet) chain tension followers?

IDK... please school me!

[Hank]

That is more of a 05-07 engine issue that was revised. A lot of the problem was with the longer oil change intervals that VW was recommending back there. All chains stretch, but that combined with gummy tensionors caused teeth to skip on those early year motors

Hank

[glibobbo21]

good thing i got an 08 motor. :-D

[All_Euro]

I keep pondering this swap when engine build time comes… good to know about the timing chain and what year engine to look for --> 08+

[Hank]

For me, the 05-07 years do not bother me too much. Most of the early year problems stem from poor oil intervals, where gummy tensioners would lead to chains skipping teeth and bending valves. It is a PITA for jettas that just want to run 200k miles without issue, but for somebody hotroding one longitude, giving it proper oil changes and taking care of the motor, I wouldn't worry about it too much. The crank's change for different years too, so a forged 05 crank won't work in a 10 block without changing all the chains and tensioners over. Same with the TT-RS stuff.

[ur20v]

So Hank, are you working on a way to convert this motor to a more traditional toothed belt and mechanical tensioner for timing duty, or perhaps a timing gear set?

These newer motors, like the 4.2 with more chains than Mr. T and dozens of tensioners bother me. The motors don't seem to be made for longevity, just efficiency and emissions and to last just long enough to get out of the warranty period.

[glibobbo21]

I think If you take care of the motor and changed the oil every 5000 or less you wont ever see a problem. Theres no room in the timing covers to convert to chains.

[Hank]

There are plenty of 200k mile chain driven Jettas out there already, or v8s for that matter. If they all failed at 80k miles, just after warranty ran out, I would be concerned, but the reality is that these failures are VERY rare when compared to the amount of engines out there. There are literally almost a million engines in circulation in North American over an 8 year production cycle. I bet you there are more 20vt cog gears that have sheered the keyway as a percentage of motors in circulation. Doesn't mean the 20vt or the new 20v is a bad engine.

Like Jim said, religious oil changing is the ticket. Where timing belts rely on mechanical springs to keep tension, and thus don't require oil to be clean and sludge free, chain driven motor need clean, sludge free tensioners to survive.

[ur20v]

Just curious as I have seen 3 different B6/B7 S4s locally (and all within the past month) require extensive overhauls due to failed/failing chain tensioners. 2 of those owners I know personally and know they are completely anal about oil changes, filter brands and factory oil ratings. The third person had their car serviced exclusively at the dealer. 2 of those three decided to dump the S4 and take a massive hit on trade-in, while the third has an extended warranty. All three cars are in the 70-90k mile range, too. Parts alone run $1500 for the repair and labor is astronomical on that underaking. Yet another person I know owns a B7 RS4 with less than 50k and hes having timing chain issues, though the dealer and AOA are stepping up to the plate... pricetag associated with the RS4 engine replacement? $20,000. Makes me want to start hoarding late 32v and early 40v motors!

[glibobbo21]

A b7 s4 engine replacement cost more than that(dealer)..forget about rs4. the timing chains arent even that bad. Try taking the motor down to bare to be machined, knowing its got to go back together in a month or 2. :-D BTDT

[nigel]

Just curious as I have seen 3 different B6/B7 S4s locally (and all within the past month) require extensive overhauls due to failed/failing chain tensioners. 2 of those owners I know personally and know they are completely anal about oil changes, filter brands and factory oil ratings. The third person had their car serviced exclusively at the dealer. 2 of those three decided to dump the S4 and take a massive hit on trade-in, while the third has an extended warranty. All three cars are in the 70-90k mile range, too. Parts alone run $1500 for the repair and labor is astronomical on that underaking. Yet another person I know owns a B7 RS4 with less than 50k and hes having timing chain issues, though the dealer and AOA are stepping up to the plate... pricetag associated with the RS4 engine replacement? $20,000. Makes me want to start hoarding late 32v and early 40v motors!

I have buddy who went through the same thing due to failing tensioners in his B6 S4, ended up spending over $10K into getting it back on the road.

[ur20v]

A b7 s4 engine replacement cost more than that(dealer)..forget about rs4. the timing chains arent even that bad. Try taking the motor down to bare to be machined, knowing its got to go back together in a month or 2. :-D BTDT

$20k is just the cost of the new RS4 motor that AOA is providing. Dealership is eating the cost of labor. Its a pretty crazy story but I love hearing the new chapters every other day or so when I stop in to pick up parts

[Hank]

Yeah, I should not have classified the 07k chain troubles in the same sentence as the v8 chain drives. They have been a nightmare.

[Lord_Verminaard]

Don't forget the 12V VR6 chain issues too. Chances are they need replaced every 80k or so. In reality, if you are doing a clutch on a VR6, may as well do the chains while you are in there. It's not a lot of extra work at that point and not much extra expense either, I kinda see the 07K as the same thing. Of course, some of you crazy's might go through clutches a lot quicker than 80k miles.

But yeah, replace chains every clutch job and it's nothing to worry about. For the V8's that might not be quite so feasible.

Brendan

[Noisy Cricket]

That is more of a 05-07 engine issue that was revised. A lot of the problem was with the longer oil change intervals that VW was recommending back there. All chains stretch, but that combined with gummy tensionors caused teeth to skip on those early year motors

Hank

I have an '05 in my care with close to 200k on the unopened engine.

I say it's 100% the longer oil change interval. Knowing appliance-car kind of owners, I'd bet that the majority of the problem cases are the ones who figure if 10k is good then it won't hurt it to go 13k or 15k or... damn the sticker fell off sometime last year, I'll take it in someday...

[glibobbo21]

lol^ sounds about right