Of course, any time you remove injectors, you really need new injector
seals, but they're cheap.

Would be cheaper to remove glow plugs instead, but my compression
test kit from harbor freight goes into the injector ports.

What was the noise like? Was it continuous (spinning mass, like flywheel,
chains, front balance pulley) or periodic (reciprocating piston/ring/conrod or valve tappet)