I removed the crappy little heater fan in the engine bay to tidy the engine bay up and i'm gonna get the 2 hose holes welded up before i refit the tinware to stop unwanted hot air entering the engine bay. Do i need to cap off the holes on top of the heat exchangers or will this stop the airflow through the heat exchangers ?
Your heating will be pretty non existent if you don't cap the heat exchangers. These holes are what allow air from the electric fan to supplement the air from the engine fan, but if not sealed the engine fan air will all leak out here. On my bus the electric fan does more work than most people give it credit for, but you need all the little flaps in place.
