If you are interested in mechanical engineering, you will need to be thoroughly prepared to jump into calculus. From the way that you worded your post, it seems to me that you will be lacking in your knowledge of algebra. If this is the case I would recommend working your way through the introductory math courses (ie intro -> trig -> college algebra) at your university/community college of choice before even starting your engineering degree. However, if you feel VERY comfortable with algebra and trig then you should be alright starting your degree in engineering. A solid background in trig and algebra is essential to avoid being "weeded out" in the first years of engineering.
If I were you, I would spend 1-1.5 years at a community college to brush up on mathematics in preparation for the beast known as mechanical engineering. It may sound like a long time, but (done correctly) math takes time to truly absorb and understand.