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Restricted Intake Thru-Hull Strainer

Anyone have advice on clearing a clogged rectangular strainer screen. I tried probing around from above and below with a coat hanger, scraper and a wire brush but was unable to get sufficient water flow for engine cooling. The water is just coming out at a slight trickle. I think the restriction was caused by corrosion. I believe the strainer is an BUCK ALGONQUIN rectangular with a replaceable perforated screen. I have two thoughts, one is to blow it out with compressed air by making a fitting for the seacock and the other is to drill through the screen from above. Anyone have any suggestions where I don't have to haul out the boat?

Thanks, Harry
 
If you have compressed air available, try using it AND water together. (I've cleaned out clogged radiators that way.) You have to fill a hose with water first, then blow the water thru the hose and strainer with the compressed air. Better still would be a high pressure water blaster (like what we use to clean the hull at haul out).

Jeff
 
Thanks for the suggestions, Jeff. The boat is on a mooring so I could bring a portable air tank but it might not hold enough air. I really like the pressure washer idea. I could bring the boat to the dock and blast it from there.
 
One of our customers has twin Volvos and the Stbd engine was overheating. The Volvo tech (under warranty) thought it was the head gasket or cracked head. The boat has a diver clean the bottom on a monthly basis. I decided to haul the boat for a two hour inspection. And there it was, a oyster in the thru-hull just pass the reach of the divers pick. It still cost the owner $3700.00 for the dealers time to trouble shoot before the Volvo tech was called and haul out.
 
Kevin, WOW!! Did the oyster at least have pearl in it? ha ha...maybe a pearl of wisdom as I learned a valuable lesson by first checking the thru-hull for obstructions. In my case I assumed the overheating was caused by either a blocked u-cooler, bad impeller, collapsed hose, bad in-line strainer or bad risers. So of course the last thing I did was pull the hoses off the sea-cocks to compare the flow rates. The stbd was a gusher and the port was just a dribbler.
 
Barnacles, oysters, and excess bottom paint in about that order. Corrosion of bronze? Way down on my list of what I see. Compressed air would not be in my top 20 means of a fix either. Barnacle glue is pretty impressive.

About every 5 years I take off my thru hull external scoop strainers and grind down to bare metal. Metal wash primer, primocon, and two coats of Trinidad is the "solution". Don't forget the INSIDE of the thruhull, using an assortment of screwdrivers, to clear it out.
 
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Went out there today with a portable container of 125psi air and a makeshift adapter using the fittings off my sprinkler winterizing system. Hooked it up to a section of 1 1/2" hose clamped onto the seacock and blasted it. Bubbles everywhere (good sign). Big improvement, but tomorrow I'll hit again.

Dave, I appreciate the advice, will definitely clean all the thru-hulls in that order when I haul it for the winter.
 
I have a follow up question as I appear to be expiriencing the same issue. Is there a way I can inspect my through-hulls without diving under the boat and without flooding the boat? :) As long as I keep the raw water hose attached to the ball valve above the water line and look down it I should be OK right? I'd appreciate any tips.
 
I have a follow up question as I appear to be expiriencing the same issue. Is there a way I can inspect my through-hulls without diving under the boat and without flooding the boat? :) As long as I keep the raw water hose attached to the ball valve above the water line and look down it I should be OK right? I'd appreciate any tips.

Well, you knocked out my two most popular ways of looking at these! I don't think a long hose will allow light enough to see what is going on down there. Although the big open hole can deliver a lot of water, the pressure is low and should be easy to manage with rags.
 
You should give it a try but just be prepared to either shut the seacock or cap it with a rag while you probe it with a long handle tool...You can't be that bad off and IF you discover a problem, you know already and can act accordingly... my 2 cents.
 
Chris--It is a bit it unnerving to have water flowing into your boat but you'll have complete control with the seacock ball valve. Plus the bilge pump should kick in and help out. Another thing you'll have is the intake hose that you removed from the seacock right there as a dewatering tool. just be ready to start the engine with the hose in the water if something should go wrong. With my boat, the water came up through the seacock about six inches or so once I got it cleared. Not a huge gusher.
 
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