@adrian2301 I took the liberty and Appended your ‘front’ so that I could connect it to my part like so:

This means that you can delete it from your file (superfluous remark: make a backup!).
Or we could make it part of the motor and put it in your file if you want to (we both modelled half of this after all and I don’t care whether it lives in your .blend or in mine…)
@blanchsb I changed my yellow to FFC72C, (which apparently is close to Pantene 123) because that looks a bit warmer to me and doesn’t hurt my eyes so much…Tested it under different lighting conditions and it looks good. I think.
Of course this isn’t a real shader yet and with all the dirt and grease and damage that will probably be added this will look completely different, but as a working base color for now…. I’ll post another render later on, so you can see it ‘in action’;)