That is the nice part about testing with a hose and water it costs nothing and you really can see from the spray pattern before and after the restriction.
The blue filter has been trashed, based on recommendations from murphy, so I made the plywood frame with aluminum window screen stapled to it. Should be fine and have plenty of airflow without doing the garden hose test. I have a temp light and gauge anyway.
Alvanko, I finally did that too. Got some 1/4" plywood cut down at the store and made one for each tractor. Left about 1" all the way around to staple the screen to. Very easy job.
Lowes has it. It is aluminum window screen, easy to cut with a plain pair of scissors. If you have a good hardware store that still makes replacement window screens you could probably get only what you need. I bought a small piece of 1/4" plywood at Lowes and they cut it to my specs with their panel cutter. Total cost on the plywood was less than $5 bucks.
a good metal screen in front of every radiator is a great idea to keep the bugs out of the coolers and radiators, that works, In this area metal screen is getting hard to find and the plastic stuff is nearly waterproof.