1982 Jaguar XJS engine blowing smoke

I am restoring an XJS and I want to keep the motor running while I do this. I have changed all the spark plugs and the car started up but is blowing grey smoke from the right exhaust and takes a long time before I can give it any revs, it only seams to start on hot days. Someone told me to check the brake fluid, I did and it is empty leading me to believe that it is sucking fluid through the manifold. Does this sound right to you? Can I remove the air conditioning unit and belt and still run the car or will this affect the motor?