Pump Casing Epoxy Repair

I have a Pentair Pinnacle pump that has developed two casing leaks at the curved "shoulders" of the main housing, just below the vertical discharge. The first leak was a seep that appeared a year+ ago & was small enough to initially ignore. Last week the other side started a pinhole squirt shooting a few feet out.

The pump performs real well otherwise so I'd like to repair it. I opened it & saw no obvious internal damage, so I'm assuming it's a porous casing problem. I tried epoxying over the leaks, first using the 2-part "J-B Weld" brand & then buying some from my pool dealer, a "Weld-On" brand stick 2-part epoxy. I sanded & cleaned the surface each time & kept the pump off 12 hours to cure, much longer than the directions on either epoxy called for.

I stopped the squirt, but water on both leaks has found a path out to the edge of the epoxy. While each epoxy was strong enough, neither bonded to the casing sufficiently to keep the water from finding a path between the epoxy & the casing.

Any recommendations for a patch that will bond to the case? Thanks.

Fiberglass resin?

It has worked well for me on things it wasn't really designed for.

I agree with social biker. Fiberglass resin adheres to almost everything. I add strands of fiberglass cloth when I need it to be extra-strong. Boat stores have the largest selection, auto-body shops also have a nice selection.

I appreciate the responses. This was my first post ... I gotta learn to write snappier titles to get more post views, but the two replies I got were quality.

When I read your fiberglas resin suggestion it was a slap-my-head moment ... I should have thought of that for this type pump casing. Probably didn't 'cause I never worked with fiberglas resin before.

So since the leak is getting worse I'll likely try the resin & cloth route this weekend. I'll buy from a marine supply, this being a wet application. If you have any other tips for a first-time resiner, let me know.

Thanks again. I do appreciate the replies.

Sounds crazy but I actually "welded" a small crack in my pump housing with a soldering iron.

Fiberglass resin is really really easy to use. Just follow the directions on the can.

Just make sure the activator is fresh, there might be a date on it. Comes in a small tube or small bottle.

Just pour a small qty of resin into a paper cup. Put the recommended number drops of the activator to start the chemical reaction. The more drops of activator you used, the faster the resin hardens (to a point).

The resin in the can will last a long time, it has a good shelf life. It's the activator (small tube) that goes bad/ less effective over time.

Stir the resin & activator throughly in the paper cup. I use a popsicle stick. Get a paintbrush (appropriate size for the work area) and brush on the resin mix onto the damaged area.

You can put fiberglass cloth (cut to size with scissor) over the resin. Use the brush to position the cloth patch and work the resin into the cloth. When the cloth goes transparrent, then its properly impregnated with resin. Brush in resin until the the cloth goes transparrent. Then you let it harden and repeat the process, if you want to add more layers of fiberglass cloth.

The resin will settle with the pull of gravity. If you can position the damaged area towards the bottom (flat), you can let gravity even out the resin over the damaged area.

You can clean up the brush and mess with MEK.

For small damages and cracks, you can also try super glue...

I used fiberglass Bondo this summer on my pump. The same stuff they make for boats. I actually used it before on my crotch rocket plastic. It's held up for 3 months, and just started leaking last week.
I just got my new Pentair Whisperflo in the mail today :D :D So I will refiberglass this one and retire it to the garage for when I need to drain my pool. It'll work, but how long is the ??

I have been doing fiberglass for many years on boats, fabrication and repairs. Polyester resin has it's limitations. It will stick to some plastics really well and others not so well. For the most part though, it's not reliable enough to say yes it is your answer. It sticks to PVC ok not great, polyethelene nope, polyurathane nope not really. It just depends on your pump housing.

The best suggestion I could give is the same as ChristopherS64. I normally use a heat gun and a nylon wire tie and a small putty knife/old kitchen knife, or a larger piece of similar plastic, and heat the case up till it gets soft and use the putty knife to weld/smooth the area over. If there is a hole to fill add the wire tie, or similar plastic and smooth it over. It sounds difficult but it is really simple and works great. Just don't burn the plastic, heat the plastic up slowly by aimming the gun at it for a second or 2 then back of for a blink of a eye, then do the same over and over till the putty knife/kitchen knife can start to move the surface around and it gets soft, keep heating it till you get it soft 1/8" in or so, and mix it around/ smear it together, add some more plastic if you need to.

I have fixed plastic valve covers on engines, plastic water holding tanks on boats, it works great and is relatively easy.

Harbor Freight sell a cheap-o plastic welding kit for around $30, I don't own it, but it should work great for this if you don't own a heat gun.

I bought that plastic welding kit from harbor freight and took it back. A heat gun with a tip that concentrates the airflow is just as effective in my opinion. You also need a air compressor to run the welding kit FYI.