What should I do here?

[Sean]

Bob,

I will say it again:  You will have overheating problems if you don't seal this door.

The opening is there for engine access.  You need to seal it with something removable.  Hinges are fine, but not necessary.

I have such a door in my bus -- it comes out completely for maintenance.

-Sean
http://ourodyssey.blogspot.com

[Sojourner]

As most of the above have posted is correct.

Bob....your answer is to put a metal (no holes or screen) door to block off engine's heat from engine compartment to avoid heated air getting into front of radiator. The outside door is screened or louver or slotted to allow cool fresh air into radiator.

The bottom-line is to achieve the coolest air for both radiator and engine's air intake to air cleaner. Make sure all isolation joints are sealed with approved sealant and opening is blocked.

FWIW

Sojourn for Christ, Jerry