Vacuum Pump Troubleshooting: Hammering Noise?

hello everyone.

I hope you can help me. I have a V70/1 with the Audi 2.5L 5-cylinder engine.

Lately, I've noticed a strange knocking sound coming from the engine. My mechanic said it's the vacuum pump.

What should I do? Should I change it immediately? The engine is running perfectly, and I'm only hearing this issue acoustically, right?

Could something go wrong? Is there a repair kit available, or will the entire pump need to be replaced? Approximately how much would that cost?

"Thank you!"

Hello!

As a T4 driver (2.5 TDI), I'm very familiar with this problem. The constant clattering is annoying, but it shouldn't cause any major issues. There's the option of replacing the lifter, which sits between the camshaft and the pump. You can also weld the worn lifter and re-machine it to the correct size, but this is only a temporary fix because the welded area won't have the necessary hardness. Workshops often want to replace the entire pump, but that's not necessary. Under no circumstances should you adjust the pump; there have been cases where the self-locking nut came loose, causing significant damage. I would remove the pump and buy a replacement lifter. However, on the T4, this solution is only effective for a short time, as the problem will likely reoccur after about 5,000 to 8,000 km. It's a quiet noise, but it starts again.

Regards, Peter.