Perko Strainer Gasket - Rubber or Cork?

[jreddington]

On my '84 E-28 I have a Perko raw water strainer, model 493. I'm replacing the gaskets. The gaskets I'm removing are cork.

Checked the Perko catalog. They indicate use ONLY cork gaskets on "older style" strainers and use ONLY rubber gaskets on "newer style" strainers. However, they don't tell you what they mean by old vs. new either by year or some characteristic of the strainer.

Not sure if this strainer is original to the boat, or if not, when it was installed but it's been there with the cork gaskets since I've owned the boat the last nine years.

Have a new set of cork gaskets. However, as you can see in one of the pictures attached the gasket (like the old one) blocks a substantial part of the strainer outlet (looks like about half the area). I also notice the seating surface on the old gaskets seemed to be only along the outer edge with a lot of "extra" gasket hanging off towards the inside of the strainer. Should have taken a picture of this before removing the old gaskets. Shows up pretty clearly.

Does this mean I've got the wrong gaskets? Are the rubber ones narrower? Can't be fatal to water flow since the engine's been running with these all along.

Based on the attached pictures can you tell if I have a "new style" or "old style" strainer. Are there specific markings or other indications to tell new from old?

Have e-mailed Perko with this question but not yet heard back from them.

 

[jreddington]

An update.

Instead of an e-mail from Perko I had a message left on my machine. Said that if the strainer dates back to at least when I bought the boat, which is 1996, that is the "old" strainer so I use cork.

Too bad he didn't catch me directly or I would have asked what the transition date was between "old" and "new" strainers and posted the info here.

Also, since it seems like cork is the correct gasket, I would have tried to get an explanation as to why this gasket covers up about half the outlet.

By the way, I did get my X-acto knife out and cut a "relief" to uncover the rest of the outlet.

 

[shard7]

I recently ran into this quandary, but since I have a 1974 vessel purchased in 2022, I have no idea how old the strainer is. Perko was no help at all (they just reiterated cork until 1996, rubber after).

So I got both gasket sets and dug a little deeper to figure this out. The key is the diameter of gasket seats in the top and bottom castings: it's about 3.62" in strainers that use rubber gaskets, whereas the cork gasket is 3.52" (same diameter as the cylinder).



The rubber gaskets extend up the side of the cylinder, so the overall diameter of the gasket and seat need to be larger (cork gaskets are flat and just butt against the cylinder).



The size difference explains why they're not interchangeable. Rubber gaskets in an older strainer won't seat correctly, and cork gaskets in newer strainers will have a gap around them.

Hope this helps others who may be unsure about which gaskets they need.