I have recently done the heads in my 1999 ford ranger 3.0 v6. It had a cracked head. I put everything back together and the truck is working fine with no lights on except for this ticking noise that I dont remember of hearing before. I bought myself a stethoscope and checked the injectors. The sound is coming from the injectors. Over the valve cover I dont hear anything as I hear on the injectors.
Someone has an idea of what is wrong? Thanks in advance

 

Injectors all make some noise. You just have to determine if the noise is normal or abnormal. You can try finding a similar vehicle for comparison, and then decide.
Unless the noise is obnoxious, I would consider letting it go for a while, as there are no really 'serviceable' parts in an injector. There's a company that rebuilds them, but I don't know what is actually done. I think Carburetor Specialties in Indiana, but don't bet the paycheck. fuelinjectorconnection.com also is on the web.
tom