Your 4.2 FSI's timing chains live at the rear of the block, and the tensioners and guides back there are failing. It's an engine-out job — and we do it at your home, properly, on a flat quote.
Audi mounted the 4.2 FSI's timing chains at the rear of the block — against the firewall — which means there is no in-car access. When the hydraulic tensioners lose their ability to hold pressure and the plastic guides go brittle and shatter, the only way in is pulling the engine, and on these cars that means the engine and subframe come out together. That's why dealer quotes on this job run into five figures.
The failure itself follows the classic chain-system arc: tensioners bleed down, the chains run slack on cold starts, and the guides — plastic that's spent fifteen-plus years heat-cycling — crack and shed fragments. You hear it as a cold rattle from the rear of the engine, and the ECU flags it with P0017 and P0341 as cam and crank timing drift apart.
What makes this one unforgiving is what happens if you keep driving: a shattered guide or skipped chain on this high-compression V8 is catastrophic — valves into pistons across two banks. At that point the car needs an engine, and good 4.2 FSIs aren't cheap or common. Caught at the rattle stage, it's a big but very doable job: chains, tensioners and guides all replaced while the engine is out, with everything torqued and timed to spec before it goes back in.
If your Audi is doing any of these, this is the likely cause:
This is the one chain job where waiting can total the car. The guides don't wear gracefully — they shatter, and when a fragment jams or the chain skips, the 4.2's pistons meet its valves across both banks. Replacement engines for these cars are scarce and expensive, and a B7 S4 or RS4 with a dead engine is worth a fraction of a healthy one. If yours is rattling cold, park it until the chains are done.
Yes, with the right setup — we assess your space first. The engine and subframe come out as a unit, the chain work happens on the bench, and the car stays secured at your place for the duration instead of disappearing into a shop for weeks. It's several days of work and we're upfront about that.
Because the chains are at the back of the block, the engine has to come out — that's the bulk of the $8,000–12,000 dealer range, mostly labour hours at dealer rates. We quote one flat price for the complete job before starting: removal, the full chain kit, reinstallation, fluids and testing. You know the number before a single bolt turns.
If the rest of the car is healthy, usually yes. The B7 S4 and RS4 are appreciating enthusiast cars, and a documented engine-out chain service is a selling point, not a liability. A healthy 4.2 with fresh chains has a lot of life left; a rattling one has a countdown.
Anything that's expensive to reach later — rear main seal, the items buried against the firewall, aged hoses and mounts. We inspect everything that's only accessible with the engine out and quote any add-ons before doing them, so you never pay engine-removal labour twice.
Send it over for a free second opinion. I'll tell you straight what the job actually involves — and if their quote is fair, I'll tell you that too.
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