Sounds like you have grease or oil on the clutch friction surface and or flyhweel and pressure plate. You can try cleaning the friction surface with brake cleaner but usually once the grease and oil is embedded and gone through heat cycles only changing will correct it.
What's the noise it's making sound like? If it's slipping, you should be able to smell it burning. Did you grease the rear main seal or soak in oil before installing? Those will often times make noise if greased rather than soaking in oil for 30 minutes to an hour, had that happen on my 40 series and once I removed, cleaned, soaked in oil and re-installed problem fixed. Sounded like a bearing chirping or scraping but was just the grease on the seal.