1982 Jaguar XJS

Hi there. 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 she fired up but is blowing grey smoke from the right exhaust and takes a long time before I can give it any revs, it also only seams to start on hot days. Someone told me to check the brake fluid and it is empty leading me to believe that it is sucking fluid through the manifold. Dose this sound right to you. Also can you remove the air conditioning unit and belt and still run the car or will this affect the motor cheers giles