Trouble in using a scanned surface in assembly

Hello,

I have a scanned surface file of an engine. I have used scan to 3d feature to make it a watertight body. But when i wanna thicken it, it shows unable to thicken. I wannted to use that surface file in an assembly to check for interference purposes( well that is all i need the Scanned file for). In the assembly only the sketches i have made on the surface for reference can be seen. Is there anyway i can use scanned surface or rather make it visible in the assembly. Cannot upload the file coz its 665 mb.

Appreciate the help.

Samio

SolidworksGeneral