Trying to get my 280 to run a little cooler. It gets up to 180 degrees and alarm sounds. Although manual says the alarm sounds at 240. Others have said their motors run in 150 range. Wondering what the washers inside each fitting on cylinder heads do. Do they limit the flow to the pee holes? Or are they limiting flow within engine? Would drilling them larger help motor run cooler. Service manual doesn't say much about them. Thanks for any feedback.