Pericardial effusion drainage tube removed 4 days ago. still getting yellow discharge bandage over tube site. how long should it continue to drain?

Briefly: Not unusual to have some drainage, but if over a week see your surgeon and may need xray or echo or both.

Usually short: Usually few days to a week. Depends on original cause, your over all health and nutrition status. In general, skin should seal in short period of time if over all health and nutrition status good and no abnormal tissue issues such as chest irradiation, etc....