knocking sound

[barney o3]

hi can anyone tell me what the knocking sound comming from the top of the engine is, the truck has been driving like a dream for the past year but ihad a bad connection on the battery annd lost all power the other nite and when i got it going again there was a constant knocking or tapping sound coming from the top of the engine, would it do any harm to keep driving or do i need to get it looked at asap. any help much appreciated

[dieselboy]

Depends where it's coming from!
What year and engine? What modifactions have been done?

Could it be something moving with the engine movement like a loose spanner etc?

[stormforce]

Because it was a bit low on oil i think it may well want the shims doing.I had a similar thing on my old 3.0 where it got so hot and i lost oil pressure on the way home from the plains.The turbo had blown and the top end was a bit tappy/rattly