Based off a noticeable number of instances of questionable verbiage in his works I'm very inclined to say he was racist, yeah. A guy that says some of the things he says would likely get thrown out of any self respecting Communist party. You can kinda say Marx himself wasn't Marxist enough.

But, Marxism is a constantly evolving and changing thing which is why we shouldn't just stop with Marx. Just as numerous physicists contributed to the science after Newton, numerous revolutionaries contributed to Marxism after Marx.

There was that one time he called Lassalle a Jewish n word in a letter to Engels.

Edit: This is the one. CW: multiple n bombs