I removed the intake manifold from my 87 300TD and dropped it off to get cleaned (just a power wash, no sand blasting). The technician asked if he could remove the large round cover on the side of the intake manifold to the right of what I believe is the engine overload protection switch (it's just above cruise control actuator, opposite from the number 5 intake port). He said it would allow him to clean inside better. I said yes, as long as he was confident that he could get it back on with a good seal. What is that round cover for, and should I have said no?

Thanks for any insight,

Zeb