A/C seawater pump sucks air (urgent)

Do you have self-vulkanizing insulation tape? You could use that stuff and roll it to make an emergency spare gasket until you can source an adequate one. However, you obviously should keep an eye on it...

Sometimes wrapping the o ring in teflon tape does the job.

Every boat should have a Loctite O ring fabrication kit aboard . You can make any O ring as long as you have the correct stock. If you run out of the supplied glue, any super glues (isocyanate) seems to work just fine.

https://www.fastenal.com/products/details/62381

That's link is for two kits and seems a bit high priced. Search before you buy.

If you have a strainer like this, make sure the plastic insert is going ALL way down, otherwise the cap will leak even when tightened...

Silicon grease (brake grease, dielectric grease, O-ring lube, etc.) might give the seal enough stick to stop the leak temporarily. I put silicone grease on all my rubber seals and hoses.

If you can't find the size O-ring you need, can you find a larger one with the right diameter material and cut it down?
- Use a razor or razor cutter to cut as perfectly square as possible. We had small guillotine cutters with different size holes to hold the stock square.
- Super glue as mentioned above works well for standard Buna-N black O-rings.
- Glue as straight as possible. We used a V-block that superglues don't stick to, probably polyethylene (Starboard). Waxed paper might work too.
- After the glue sets, stretch the joint over something and sand it lightly all around, to thin the hard spot where the glue is. The glue should set up in seconds.



A big centrifugal pump will erode the impeller and case from air bubbles passing through, I would not run it any more than necessary.

The O-ring cutting and aligning jig is available from McMaster for $3.14. That, superglue, a razorblade, and some O-ring stock (or a selection of large O-rings) is all you really need. I think I'll buy one for the shop and one for my boat at that price.

https://www.mcmaster.com/#9462k2/=18wqtmi

Full O-ring kits are in the $40 and under price, that adds another box you don't need taking up space though.

Racor "O" rings are laying around on most boats. The stock doesn't have to be round in cross section for any sea strainers I'm familiar with. The jury rigged "O" ring can have more than one joint, if necessary. Forgive me for pointing out the obvious, but most of the time solutions are hidden in plain sight. All good tutorials and tips from the above posts.

In that Loctite kit you get a plastic device that squares the cut (uses a safety razor) and it has V grooves at each end to align the new O ring when glued. There are no O rings in the kit what you see is straight stock of varying diameters. If I get a chance a snap a pic latter.

Hers a better pic and price
https://www.walmart.com/ip/112-O-RING-SPLICING-KIT/23548043

What's kind and brand of strainer? Many have a seal, not an o ring. If you're I don't have any rubber material, you can make flat seal with duct tape... make a square with multiple layer ( 5 or so) then cut to shape

That yellow cutting and gluing jig is what I used to use, made hundreds of O-rings for industrial vacuum chambers. Meters long, they had to be perfect, I got pretty good at making them. The glue doesn't stick to that jig.

The McMaster jig has shorter grooves for lining up and gluing each size of O-ring, maybe that would be better for making small O-rings...?

Depending on the strainer cap, OP may be able to prevent the air intake from the cap by wrapping the cap with teflon tape. Naturally this is just for emergency, but should do the job.

Good point about the non-stick Loctite brand Jig, the V groove gives you only 2 points of contact, that allows for excess glue to be pushed out..................I've made O-rings as small as 1 " in diameter. Finding small O-rings isn't a problem. It's 1" to 12" or larger