I'm only going to say this once because this debate doesn't particularly interest me - sola scriptura (bible alone) Christianity is not biblical in and of itself.
"I commend you because you remember me in everything and maintain the traditions even as I have delivered them to you" (1 Cor. 11:2).
"Follow the pattern of the sound words which you have heard from me, in the faith and love which are in Christ Jesus; guard the truth that has been entrusted to you by the Holy Spirit who dwells within us" (2 Tim. 1:13-14).
"So then, brethren, stand firm and hold to the traditions which you were taught by us, either by word of mouth or by letter." (2 Thess. 2:15)
"You, then, my son, be strong in the grace that is in Christ Jesus, and what you have heard from me before many witnesses entrust to faithful men who will be able to teach others also" (2 Tim. 2:1-2).
"First of all you must understand this, that no prophecy of Scripture is a matter of one’s own interpretation, because no prophecy ever came by the impulse of man, but men moved by the Holy Spirit spoke from God" (2 Peter 1:20-21).
"‘Though I have much to write to you, I would rather not use paper and ink, but I hope to come to see you and talk with you face to face, so that our joy may be complete" (2 John 12).
Of course all these references were made prior to the New Testament's canonization. The primary method of evangelism and preaching was word of mouth since the "Good News" was not yet a published work.
Since the traditional church (Roman Catholic, in this case) was one of the chief preservers of Scripture through the ages, certainly they would have preserved reference to Mary's sinlessness if it existed? Where is the reference?