Perko Sea Water Stainer - Cork Gaskets

[Capt.Don]

I have a water leak from the Perko sea water strainer. From what I can tell, the leak is from the brass, cork and plastic seal. I've disassembled, purchased new cord gaskets, etc., but it is still leaking.

A bit of background, the Perko sea water strainer is a brass frame, with a plastic clear cylinder, mounted between the top and bottom brass frame assemblies using cork gaskets. Somehow, this all seats and doesn't leak!

Is there a sealant that applies between the brass frame and the cork gasket? How do I set/seal the cork against the brass? Likewise, should i use the same/similar sealant between the cork and the plastic cylinder?

Any advice on reassembling the Perko sea-water strainer is much appreciated. Also, is there a recommended torque on the bolts that make the frame? I don't want to over-tighten these.

Thanks for your input,
Don

[HopCar]

You should not need any sealant. The gaskets should make the seal. The Perko 0493 Series Strainer were originally produced with cork gaskets but have switched to rubber gaskets. They are not interchangable. If you have one designed for rubber gaskets and put in cork gaskets, that might explain the leaks. How old is the strainer? Is it a 0493 Series Strainer?

[HopCar]

Here is a link to the Perko website showing the 0493 series strainers: PERKO Inc. - Underwater Hardware - Intake Water Strainer

[Capt.Don]

HopCar,
Thanks for the info and link. The model looks like the 0493 (link above). The unit is about 12 years old. I removed the top and bottom cork gaskets and replaced with Perko replacement cork gaskets. After running the engine, I see water dripping by the bottom corners.

The funny thing was the top lid had a rubber gasket. I'm thinking that this may have been the source of leak all along, since the discharge fittings, hose and hose-clamps were all corroded. I also replaced the rubber gasket with cork.

If it is still leaking, I'm thinking about taking apart (again), cleaning the bronze where cork seats. Any thoughts on how tight the 4 corner rod/nuts need to be to seat and seal against the cork?

I need to look at this again in daylight (it was late last night), to make sure still not leaking. I'm also hoping the cork has a chance to soak and might tighten up the seal!
Thanks,
Don

[skipmac]

Originally Posted by Capt.Don

HopCar,
Thanks for the info and link. The model looks like the 0493 (link above). The unit is about 12 years old. I removed the top and bottom cork gaskets and replaced with Perko replacement cork gaskets. After running the engine, I see water dripping by the bottom corners.

The funny thing was the top lid had a rubber gasket. I'm thinking that this may have been the source of leak all along, since the discharge fittings, hose and hose-clamps were all corroded. I also replaced the rubber gasket with cork.

If it is still leaking, I'm thinking about taking apart (again), cleaning the bronze where cork seats. Any thoughts on how tight the 4 corner rod/nuts need to be to seat and seal against the cork?

I need to look at this again in daylight (it was late last night), to make sure still not leaking. I'm also hoping the cork has a chance to soak and might tighten up the seal!
Thanks,
Don

Just replaced the cork gaskets in my old Perko. Have not launched yet so don't know if it will leak. I think you may be on the right track to disassemble the strainer to check the seating. I did spend a lot of time cleaning old cork out of the grooves in the bronze top and bottom. A little residue there could easily cause a leak.

[Nicholson58]

I never re-assemble anything with a gasket, especially cork, without a thin film of a carefully selected gasket maker. For water, I suggest any of the non-hardening silicone rubber types under the Permatex brand. I got tired of oil dripping from the valve cover cork gasket on our 6-cyl Westerbeke. I installed a new one with black, oil tollerant form-a-gasket. End of problem. Same issues with our raw water Groco strainer. Blue Permatex - no leaks. By the way, a leak here can let air in as well as water out. This can shut your cooling system down.

Sometimes the sealing surfaces get crevice corrosions, pits or other blemishes that make the original gasket insufficient alone to make a tight seal.

[HopCar]

The suggestions to make sure the mating surfaces are smooth and clean are of course correct. A little gasket sealer on the cylinder gaskets wouldn't hurt but shouldn't be needed. Don't put sealer on the cover gasket unless you are willing to replace it every time you clean the strainer. It doesn't take a lot of tension on the side rods to make the seal but you do want all of the rods to be about the same tension.

[Capt.Don]

Success! Thanks to everyone for the help.

What I found was corrosion and/or salt buildup on all the brass surfaces. I polished, first with sand paper to remove the buildup and finish with steel wool. I made sure all the surfaces were smooth and shiny. It is interesting that it looked like sea water was seeping from the top brass body.

I went further and smoothed out the top and bottom edges of the plastic cylinder. As an aside, the inside clear plastic cylinder had an algae or green oxidized buildup, so it was not clear, but dark green. I scrubbed this with liquid bar-keepers friend, so I can now see into the filter basket.

As far as reassembly, I put the 4 corner nuts at finger tight and then about 3 or 4 1/4" turns on the wrench. I made sure they were about the same tension. I also tightened them opposites to keep the pressure even.

For testing, I ran the engine to temperature, no leaks. I then turned off the engine, still no leaks. This is where it was leaking last night. Definitely polishing all the brass surfaces was the solution. I also think the cork became saturated and forms a better seal. All in all, I'm happy with a nice, clean, shiny, not leaking, sea water strainer.

Thanks everyone!
Don

[HopCar]

Nice job. I bet you saved a couple of hundred dollars by doing the job your self.

[Nicholson58]

Good work!. With so many things, often its something simple in the end.

On the algae, I found that drawing the water down a bit and re-filling with Clorox is deadly on the algae. Plastic cylinder is spotless. I pump it into the engine after a few minutes an let it sit there for a while. Then start the engine and let it flush thoroughly. Fist time i did this a lot of black sludge was discharged. I'm sure this also kills all critters nesting in the lines and heat exchangers.

[Capt.Don]

HopCar,

Originally Posted by HopCar

Nice job. I bet you saved a couple of hundred dollars by doing the job your self.

I never thought of it that way. What started as a simple replace a 11" inch hose and a couple of hose-clamps, cascaded into taking apart the Perko, which lead to replacing the cork gaskets...... I suspect the corrosion problem that rotted the hose and hose-clamps was due to the upper gasket, leaking salt-water onto the hose. Overall, this is a good thing to repair. There's also corrosion on the front engine mount, which I thought was due to the water-pump, but again, may have been due to this gasket.

I don't mind doing these things myself. To me, it is all part of making sure I understand how these things work and I'm able to deal with when on the boat with my family. When I saw the corroded (non-existent) hose clamps on the sea-water intake, this set off alarm bells. I'd hate to discover the boat is flooded because the hose came off the pump.

I appreciate everyone's input. I'm pleased with the outcome - now onto the next project!
Don