Is the following sentence grammatically correct:
I was wanting to know if I could sent you a link.
It does not sound correct to me.
"I was wanting to know" is fine. Use 'send', not 'sent', then it will be OK. Using a complex construction like I was wondering whether... or I was wanting to know if ... is one way to be polite, as a commenter has said.
The construction is considered more polite because it tells the listener about the speaker's desire to know something, without directly asking.
I would say no, "I was wanting to know if I could sent you a link." is not grammatically correct.
"I want to know if I can send you a link."
Or if you are referring to an action (such as asking someone previously if they had Internet access, for example) past:
"I wanted to know if I can send you a link."
you: "Hey do you have Internet access?"
them: "Yes, why do you ask?"
you: "Oh, I just wanted to know if I can send a link to this groovy site about the English language & usage."