Perko sea strainer caps

northshore

northshore

Well-Known Member
Jan 17, 2011
2,089
Cleveland, OH
Boat Info
1989 340 Sundancer
Raymarine E90W Radar/Chartplotter
Engines
Twin 454 Mercruiser 340's
Looking to do a project to help the engine winterizing go a bit quicker this year and need and additional set of caps for my sea strainers. Anyone have a good source?
 
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northshore said:
Looking to do a project to help the engine winterizing go a bit quicker this year and need and additional set of caps for my sea strainers. Anyone have a good source?
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I found the pictured "Mechanical Test Plug" at Home Depot for about $5. Screws right in to my strainer and already has a hose fitting on top.
 
Both great ideas and much cheaper - thanks!
 
Those ideas will work well for a Groco but not a Perko.
 
JVM225 said:
Those ideas will work well for a Groco but not a Perko.
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I would think Perko still makes replacement caps for the older strainers. I know the newer style, 2005 and up, are available with hose inputs and valves for flushing. Those newer caps will not fit the older strainers, as confirmed by Perko directly. I am machining and threading my old caps and installing garden hose female couplings in mine this winter while the boat is resting.
 
When I bought my boat, the P.O. showed me all of the T fittings and plugs he installed all over the place to facilitate winterizing.

I ripped them all out since they were set up to accept 3/4” hoses while the system is actually 1 1/2”. Everything I read about flushing or winterizing is very specific about NOT stepping plumbing down in size. Starving the pump seemed to be what was behind that and I agree.

Flushing under hose pressure is fine I imagine since you’ll be pushing more water in than the pump would draw through the smaller hoses.

With my system returned to stock, I winterize using a container with fittings and a ball valve with a 1 1/4” ID. This size hose barb fits right into the stock 1 1/2” hose on the incoming side of the pump with only a minor reduction in size.

Once connected, there are no leaks and I can open the valve, casually climb back up to the helm and start the engine.

That container is drained in a few seconds at a pace in keeping with the needs of the pump.

Recently I saw a guy fighting to winterize a pair of inboards using one of those plunger flusher things jammed under the boat. He had a pail of anti freeze on an 8’ step ladder trying to create pressure to prime the pump.

Upon starting the engine, the pail drained painfully slowly through the 1/2” ID passages and then stopped going down. His pump was moving more air than liquid and the impeller failed.
 
Irie308 said:
This works on your strainers? Did you try one for your genny?
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I actually have a 2" threaded PVC fitting that works on my gennny and air conditioner strainers. I only linked the one from Defender to show the OP that they were available off-the-shelf.
IMAG0338.jpg
 
I've tackled this 3 different ways...

Previous boat - Didn't require removing caps to flush/winterize...
enhance


This boat, also doesn't disturb the caps but requires screwing in a plastic nipple...
enhance


Both boats, I use this for the gen and for the air condx. An extra cap was purchased, drilled, tapped and fitted with a boiler valve. This is only used at winterization time. During the season the regular caps are in place...

enhance
 
in the big box store , by the galvanize pipe fittings you can find the flange that allows you to fasten a pipe to the floor or wall such as a hand railing. If you get the two inch pipe size , it matches up to the perko strainer pretty close, kind of like a perko cap with a large hole in the center. fashion a gasket to sit it on top of strainer tight.. Reduce the thread size to whatever hose you want to drop in a bucket and away you go.
 
Sublimetime said:
in the big box store , by the galvanize pipe fittings you can find the flange that allows you to fasten a pipe to the floor or wall such as a hand railing. If you get the two inch pipe size , it matches up to the perko strainer pretty close, kind of like a perko cap with a large hole in the center. fashion a gasket to sit it on top of strainer tight.. Reduce the thread size to whatever hose you want to drop in a bucket and away you go.
Click to expand...
Thats a great idea. Do you have any pictures? I have a 1 1/2" perko strainer for the engines and 3/4 for the a/c and Gen. I thought about buying a new cap and drilling, but your method is a bit cheaper
 
Matt Michels said:
Thats a great idea. Do you have any pictures? I have a 1 1/2" perko strainer for the engines and 3/4 for the a/c and Gen. I thought about buying a new cap and drilling, but your method is a bit cheaper
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I did the same for the engines and the gen and A / C I use a 3/4 circulator flange from a boiler fit perfect
 
Last edited:
Sublimetime said:
in the big box store , by the galvanize pipe fittings you can find the flange that allows you to fasten a pipe to the floor or wall such as a hand railing. If you get the two inch pipe size , it matches up to the perko strainer pretty close, kind of like a perko cap with a large hole in the center. fashion a gasket to sit it on top of strainer tight.. Reduce the thread size to whatever hose you want to drop in a bucket and away you go.
Click to expand...
Clever
 
Hi.
hi.
i have installed two t ball valves in front of the seawater pump, the two branches connected with a t piece. the middle end piece goes on deck to a threaded hose connector.
I can connect the 20-litre antifreeze tank there with a ball valve.
Close the seacocks, open the stb machine t ball valve and open the frost protection valve.
Start the engine and fill it with antifreeze.
Stop the engine, switch to the other machine.
After both engines are filled, the rest of the antifreeze runs back into the perforated screens and valves.

Done.
Do not disconnect any hoses or climb into the engine compartment, just switch the taps and that's it.
 
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