Cam belt change recommendations

[FrenchAudi]

I was interested to read a recent discussion, now closed, on cam belt replacement intervals, now apparently every 140k miles for a 2013 A3.

I assume recommendations are similar for other models, and thought I would describe my recent experience.

According to the historical Audi maintenance schedules in my Bentley manual, the replacement intervals for the belt on my 1996 1.8T have been as follows:

1996-97: No recommendation. 1998: 190k miles. 1999: 105k miles. 2000: 105k miles. 2001: 120k miles. So the latest one was 120k miles or 192k km.

I always carry out maintenance at well below the recommended intervals, and after reading opinions and experiences on various forums, including here, I decided to change mine at 120k km (75k miles), or 6 years.

The Avant had only covered 43,000 km when I bought it, but was 20 years old, so I replaced the cam belt immediately.

Due to Covid and having another car for short journeys, by May this year the Avant had only done 77k km on that cam belt, but as it was just over 7 years since the previous change, I decided to replace it.

I found the tensioner had reached the limit of its travel, and when I compared the belt with the new one it was significantly stretched. Both belts were Gates, and purchased recently from major online suppliers, so should have been new stock.

On the basis of this experience it seems that the time between changes may be more important than the distance covered.

[Crasher]

It is a subject open for much debate and it could take a few years to get a feel for all of the myriad variations even almost the same engine such as the 1.8T. My Octavia and Mrs Crasher Polo are both 1.8T and use different tensioner systems.

[FrenchAudi]

The cam belts on our Alfa boxer engines (we have had 4) have spring loaded tensioners.

Once the belts have been changed and the engine turned over a couple of times to bed them in, the tensioners are allowed to take up any slack at a specific, marked, crankshaft position (which is where all valves are closed) and then locked in this position.

So, unlike those on the Audi, the Alfa tensioners do not exert constant pressure on the belts, but just act as guides.

I have never found the belts noticeably slack on any of our Alfas, and wonder if the constant heavy pressure from the Audi tensioners tends to stretch the belts and reduce their life.

[Crasher]

It is a good point, thinking back to the old EA827 engine with a roller which was set and stayed there, they never failed even after years but the same belt on a Golf 3 would fail and these had spring loaded tensioners.

[FrenchAudi]

I didn't expect the Audi belt to be noticeably stretched, I only checked it against the new one because the tensioner was at the limit of its travel. Although it had been in use for a year over the six years recommended, it had only done 77,675km - 48,547 miles. Well below the current 120k or even 140k miles recommended by some sources.

I may look at a way of tensioning the belt with all valves closed, and locking the tensioner in that position next time I replace it.