Mixture of sweep mesh+Tetrahedral mesh in a 3D model

I have a helical coil embedded in solid cylinder and was trying to figure out best way to mesh it since helix always creates problems.

1)I did a mapped mesh on one end of coil cross section.
2)Swept it along the coil, till the destination face.
3)I meshed the cylinder with tetrahedral mesh.

I am always getting errors. The model is just not meshing. I tried meshing complete model with tets and it did mesh after a looong time, but it gave error while solving.

Would really appreciate if someone could give some guidance.

Thanks