A louder than normal diesel knock has started for no apparent reason this week while on a 40km trip & has not gone away since then.
The engine is noisy at idle & right through the rev range as though it has somehow advanced the timing or something.
Also the idle speed has increased slightly.
When you rev up the engine it comes back normally until it gets to about 1200 rpm when it picks up slightly before coming back to idle just like you gave the accelerator a small blip.
The vehicle is a 2001 Silverado crew cab long bed, Duramax / Allison converted to right hand drive 4 years ago, 265,000km (no add on extras)
I changed the fuel filter yesterday which looked perfect anyway (no change), the injectors where replaced at 180,000km.
This has always been a great truck & regally tows a 30-ft gooseneck & race car around the country without any problem until now.
Hoping someone has an easy answer?
regards Terry