Generator Sea Strainer Cap Won’t Tighten Down

Make sure the basket is seated in the bottom of the strainer. Pull the basket out and look at the bottom you will understand what I mean then. Sometimes it takes a wiggle to get it to seat

 

Photos?

 

Agree, some photos would be good

 

Do you have the older perko style with cork orings? Another option would be to use RTV sealant to create a new gasket. Clean up the top, place a bead of RTV, smooth with your finger, and let it sit for 24hours. Provides a great rubber-type seal.

 

Does it clamp down if you remove the o rings?

 

I believe your issue is the blue thing in the sea chest. I have never seen that type of material in one of these.

 

Bolt threads look possibly worn down. Since it’s the only thing you didn’t replace, I’d evaluate those now. Did you try threading the nut all the way to the bottom of the bolt to test out the grab the whole length? Or big clamp to clamp the lid on. If it still leaks then not the bolt probably

 

Given the year of your boat, I can only assume you have an older Perko strainer which came with cork gaskets. They (Perko) states that you must continue to use the cork gaskets with that model. The newer models make use of the rubber gaskets. Some have stated that the rubber works in the older models.

https://www.perko.com/catalog/underwater_hardware/103/intake_water_strainer/
*Note: Older model strainers utilizing cork cylinder gaskets must order 99M Cork Gasket Kit and newer model strainers must order 99R Rubber Gasket Kit.​

A set of new cork gaskets will run you $20-$30, with the hardest challenge finding out what # Perko you have, and ensuring that your getting the right gasket set. You can get just the lid gasket 99N (set of 2), or the entire set 99M which includes the lid, as well as gaskets for the top and bottom of the clear cylinder.

Looking at your first picture - is the o-ring installed on the cap, or is that old cork? Either way - there is not enough stuff there to create a good seal.

 

The bolt also looks sketchy....worn down. Is the wing nut(s) slipping on it?

 

What you call a tapered bolt looks like it was originally a larger diameter thread.
It may have been re-threaded for a smaller wing nut that can’t go all ghe way to the bottom
That plus the missing gasket

 

I have these same strainers and had the same issue with what you’re calling that tapered bolt.

It’s actually flattened on 2 opposing sides and as a result there’s reduced thread area. Yours is stripped to the point that the wing nut thread can’t get or maintain a hold.

You can probably get replacements but they’ll have that same design flaw.

I replaced 2 of mine with brass threaded rod with flats filed only at the bottom where they’re needed to fit into the housing where they pivot. I cross drilled them for stainless machine screws and Nylock nuts.

Also, you need the cork gasket. I glued the cork into the recess in the lid with RTV and greased the sealing surface with silicone grease so the cork doesn’t stick to the rim of the bronze housing.

 

In looking at your pic again I see that your particular part is not flattened on 2 sides since it’s the smaller strainer. I have that size for my AC but larger ones for my raw water cooling intakes. Those are 3/8 16 NC and have the flats and are where I had this problem.

You should still be able to fabricate a new one out of threaded rod though and it’ll be simpler to do without the need for the flats.

Odds are good that your larger ones are as I described.

 

Not worth the risk of loosing the boat; new strainer needed.
https://www.defender.com/product.jsp?path=-1&id=3352441