Hazard! Unintentional & effective engine raw water strainer

[Captn_Dwt]

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

[jleonard]

Glad you found your problem.
However, I have never seen any debris get past my raw water strainer. If you have a strainer, you should make sure it's working properly.
I know the one that was on my boat when I bought it was the original and it was a piece of crap. Holes were too large (IMO), and it didn't appear to seal all that well. I replaced it before I ever ran the boat.
If you do not have a strainer, you should get one.

[Captn_Dwt]

Good Point. Note that the partial obstruction I found in the current repair involved some "gunk" and some particles, so the strainer screen is part of the issue, but so is contamination that will pass most any screen.
That said, I did note two things: (1) The old style GROCO strainer does indeed have a screen with round holes that allow much to pass. (2) I replaced that entire unit with a new style GROCO strainer that has a nice, fine-screen element; but...when I clean it each Fall, I find that items like pine needles have passed through.
So...my final point is this: It's SO EASY to flush this part of our cooling system once a year...why not do it and be assured that nothing is building up at this point.