It seems that in order to determine if ideology can be separated from idology you have to define ideology. My favorite definition comes from Terry Eagleton in his first chapter of "Literary Theory". Eaglton says that everything society constructs is ideology. This means your cultural beliefs, your ideas of norms, and what you believe is morally right or wrong. Eagleton also says that ideologies help shape and control what people do.
Now, taking Eaglton's definition of ideology, I don't believe it is possible to separate science from ideology. Yes, sceince is supposed to be based on cold, hard, unchangeable facts, but where are these facts coming from? Data is recorded by a person, probably someone influenced by a set of idologies. Every person's histories and ideas influence what they see and interpret in the world, and if they are interpreting "scientific data" then they are influencing it to fit them. Not saying that they will deliberatly change a result of an experiment, but that they may view things differently than someone else.
It is impossible to say that all science is objective. There are many tests out there that require some subjective opinion to determine the results. For example, Gram staining is used to distinguish between two types of bacteria. One type stains a violet/blue while another type will stain red. Depending on how well the staining was done, the contrast between the two colors is either great or not. If too much decolorizing happens, then the violoet cells may appear pinkish red (of course a good scientist would repeat the staining procedure to obtain definite results, but this does show that there is some subjectivity involved in science). What one person belives is violet could be a dark red for another.
Science seems to recognize these subjective errors, and new tests are constantly made to overcome these problems. For example, certain machines measure how much light is able to penetrate a vial of bacteria, and give a solid numerical value for the amount, rather than a subjective "a lot of bacteria". There are also tests done to eliminate the influence of the researcher entirely just in case his/her beliefe is so strong they unconsciously influence the results of the experiment. These "double blind" experiments eliminate these problems.
Everything people view is subjective, even science. Certain measures can be taken to help eliminate some of this subjectivity, but it is always around.