autman

I'm not sure if Duke's problem is this, but it is worth checking. I overhauled a 1993 KA24 engine for a D21 truck about 2 years ago. It has had a rattle noise at crank up ever since. I just figured it was the lifters. Noise goes away after oil pressure builds. Lately I noticed a louder rattling noise when revved. The noise gets louder with rpm. Come to find out the lower alternator mount bolt was not tight and had beat the alternator mount hole into a keyhole shape. I discovered this with a stethoscope while under the vehicle. I changed the alternator and noise is gone. The engine still has a rattle at crank and slight ticking at idle which goes away when revved slightly. Possibly lifter bleed down. BTW Oil pressure is: 70psi cold idle and tapers down to about 10 psi after hot 50psi when revved 2000 This problem bothered me for a year or so. I was thinking piston slap, detonation , wrist pin, low oil pressure and everything. Guess you have to check the simple stuff first.