Hazard! Unintentional & effective engine raw water strainer

[Captn_Dwt]

I've been overhauling all the water systems on my Ford-Lehman 120. I'm now finished with the Raw water system, and feel that this can apply to ANY engine that has oil / transmission coolers in the flow - line of the raw water. (Hence, I'm posting here as well as with the Classic Trawlers.)
These coolers can act as filters; they can plug up with junk; they can slowly choke off the raw water supply.

I had planned on replacing my oil and transmission coolers because of age. I purchased new units and a complete hose-kit from American Diesel, and began the tear-down phase. There was also a "spare" cooler that came with the boat. No explanation on the wrapper...just "Spare...replaced at 700 Hrs". I inspected it...and noted that one end of the cooler was plugged! With eel grass. Hmmm, I wonder. I could also tell that this had been used in the Engine Oil position. (on our motors, the Engine oil and Transmission coolers are identical / interchangeable). Finally, after the raw-water pump, the next item in-line is the oil cooler.

So, as I removed my oil cooler...sure enough...partially plugged with goop / pine needles / stuff. Now i know why she ran a bit hot last year, and why my exhaust elbow showed signs of high heat!
Ok...For me, it's clear that each year at haul-out, I'll be disconnecting and back-flushing this cooler! (for this engine at least, it's very easy to do).
I'll also know that if she seems to be running a bit hotter than normal, this is one likely culprit.

Knowledge is Power!
Best wishes,
Dwight