We (QEII Repair) have no experience in the unibody Macbook/Macbook Pros, but we can recommend that you check the fan casing for any foreign contaminant that may be jamming or slowing the fan down. If that fails to solve the problem, you might want to replace the fan. (If anyone else posts further advice, try that first). A temporary solution until the fan is fixed is to use an external desk fan to keep the exterior of computer cool and if there are any ventilation holes in the unibody macbook pro, use them to input cool air to keep the system fresh; and stop that loud fan from having to work at any more than idle pace.