1HD-FT engine rattle solved.

[frank rabbets]

Started to hear a mechanical clatter from front of engine a few years ago. Now much worse in cold weather. Started engine today to investigate and it sounded like the noise was coming fro the AC pump or inside timing cover. I noticed that there was play in the loose run of the ac belt. Jerky play, not constant. With engine running I adjusted the belt slowly and the noise slowly disappeared. Now the belt did seam quite tight before but obviously not tight enough. Belts usually make a screeching or grating sound but I've never come across a load mechanical rattle. No play in bearings. Noise was a little softer with hot engine perhaps because of softer warm rubber belt.

 

[Lorin]

May be worth checking there’s no play in the harmonic balancer…..

 

[Shayne]

Grease top pulley of a/c belt

I can't actually remember Frank but I'm thinking its just a wheel spinning on a pin which will inevitably wear when grease is gone .