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D4 - Fuel and Exhausts Everything to do with getting fuel into the engine, and fumes back out again

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Old 21st July 2024, 06:54 PM
Saff Saff is offline
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Default hpfp belt

Good evening all.

Just looking under the bonnet of my D4 4.2 tdi looking at the serpentine belt with a view to change when I replace my A/C compressor (another story).

I noticed that the High Pressure Fuel Pump is driven by a toothed belt. This is all news to me. Anyhow, I presume this has a replacement interval and was wondering what it might be in terms of time/mileage. Is anyone able to enlighten me and is it an absolute pig to do? It certainly looks to be given its location at the rear of the engine.

Cheers, Steve
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Old 22nd July 2024, 07:03 PM
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Start from page 364 of the following PDF from the D4 Technical Info & Upgrades Sticky thread:

10-Service Manual 8-cylinder TDI engine (4 2 ltr 4-valve common rail).pdf
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Old 23rd July 2024, 10:07 AM
Saff Saff is offline
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Hi Sean and many thanks.

It doesn't appear too bad after reading this, possibly a little awkward. What I can't seem to find is a schedule to replace the belt on an age/mileage basis. It seems that the belt is low-stressed therefore unlikely to fail but I can't help thinking that it would still deteriorate with time. Belt failure would not cause damage as such merely failure to proceed I can only assume owners don't bother changing it.
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Old 24th July 2024, 10:38 AM
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Quote:
Originally Posted by Saff View Post
What I can't seem to find is a schedule to replace the belt on an age/mileage basis.
Not an A8 or 4.2tdi, but this thread about a A6 3.0tdi raises the same question, with the responses being that there is 'no schedule', and in the event that it does break, all that happens is the car just stops. Someone suggested just doing a visual inspection, with another suggestion being that if the other belts are being replaced, you could add that one as well while you're there. A bit like replacing the thermostat when you're replacing the water pump.

https://www.audi-sport.net/xf/threads/213064/

Also, no reference whatsoever in the Maintenance document for the D4 A8:

27-Service Manual Maintenance.pdf
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2001 A8 D2 FL 3.7 Q - LPG Conversion, Engine: AKC, Gearbox:FBB, Colour:LY5X Aqua Blue pearl effect, Interior:WJ light beige/dark beige valcona leather with burr walnut inserts

My DIY jobs - Replaced alarm horn, Replaced Coolant Temp sensor, Updated RNS-D firmware, Installed Reversing Camera and Digital TV, Dashcam Installation, Retrofitted Rear Blinds, Auto-Dimming Rear View Mirror, Chrome Boot Struts

Sold! 2008 S8 D3 5.2 V10 - Engine: BSM, Gearbox:KLW, Colour:LY7F Suzuka Grey Pearl Effect, Interior:Black/Black with Silver/Black valcona leather with carbon atlas inserts, Bang & Olufsen, Heated windscreen, Soft-close doors, TV, DAB, AMI, Quad Zone, Auto Boot, Auto dim Mirrors, Keyless entry, PDC with rearview camera, AFS II Headlights

My DIY jobs - Fan Jet Windscreen Washers, Retrofitted Electric Side Blinds
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