what can cause heavy yellow discharge without odor?

Hello Anon

Thank you for writing.

Yellow discharge can mean an infection, even with no odor.
But the yellow color can also be a result of natural discharge mixed with oxygen and is not serious.
Discharge that is heavy can mean a woman is ovulating. Have you noticed when this discharge happens? If it's a few days mid-month, it's likely harmless discharge. But if it's constant, a quick checkup is a good idea to rule out an infection, including a yeast infection.
Best,
Susan