Pump Fitting Will Not Stop Leaking, Please Help Me

[JOEY_G]

Hey everyone,

I had to replace a cracked pump housing on my ~2000 Caldera spa. The previous owners were NOT good at any kind of maintenance and I think they may have somehow ruined the PVC fitting on the pump. I installed a brand new aquaflow wet end, and reinstalled the 2" PVC flange fitting with 3 wraps of teflon tape on the male threads. I put it reasonably tight with a pipe wrench and it leaked out just about everywhere it could have. So I removed it, cleaned and dried everything, and put 6-8 wraps on the male threads, and installed the nut to the highest torque I was comfortable putting on plastic parts. It still leaked between the nut and the pvc pipe, but not nearly as much as before. There is purple residue (from the PVC cement stuff) in many places on the fitting, but it doesn't really look like it was glued on before, and it wasn't too hard to get off. I think it could have been from the original assembly of the piping in the system, but part of me is afraid the previous owner roughed up the PVC flange sealsurface with glue. Am I missing a step in the installation? I am going to cut the fitting off and replace it if I can't figure this out... Or just use solid PVC fittings that cement together. I am so sick of leaks.

Images below: A similar pump, the white fitting on top is the one leaking:

The sketch below shows the cross section of this fitting. the black is the pump (male threads), the blue is the flange nut (female threads) and the red is the PVC flange.

[Hotrod]

Teflon tape is not required on a union like that however a oring or a ribbed gasket is.

[JOEY_G]

Teflon tape is not required on a union like that however a oring or a ribbed gasket is.

Son of a !@#*()$&. I didn't think they looked like tapered threads. I am VERY unhappy with the local hot tub store. He said they use teflon tape, not any other method of sealing. Last time I go there. He is clearly a salesman and nothing more.

So please enlighten me, does the o-ring or ribbed gasket go in between the pump fitting and the PVC flange (betweek the red and black)? That is where I would assume it goes. Or does it go under the PVC nut on top of the flange (between blue and red).

If it goes where I think it does, it would increase the height of the assembly that the nut threads onto and allow more pressure on the nut/flange interface before the threads bottom out. Possibly preventing a leak between the PVC flange and nut. hmmm....

Thank you very much for your very prompt and informative reply. I appreciate your help.

[Peteyboy]

Teflon tape is not required on a union like that however a oring or a ribbed gasket is.

Son of a !@#*()$&. I didn't think they looked like tapered threads. I am VERY unhappy with the local hot tub store. He said they use teflon tape, not any other method of sealing. Last time I go there. He is clearly a salesman and nothing more.

So please enlighten me, does the o-ring or ribbed gasket go in between the pump fitting and the PVC flange (betweek the red and black)? That is where I would assume it goes. Or does it go under the PVC nut on top of the flange (between blue and red).

If it goes where I think it does, it would increase the height of the assembly that the nut threads onto and allow more pressure on the nut/flange interface before the threads bottom out. Possibly preventing a leak between the PVC flange and nut. hmmm....

Thank you very much for your very prompt and informative reply. I appreciate your help.

Sorry to jump in - there is usually a slot the o-ring goes into on the union flange.

[JOEY_G]

Hmm. I looked for one during disassembly and didn't find one. I will check again when I take it apart again. Is the groove on the bottom or top of the flange (in the sketch I posted)?

thanks

[Hotrod]

between the black and the red on your drawing

[JOEY_G]

between the black and the red on your drawing

Thanks. I will probably be up and running tonight!

[JOEY_G]

I went to the local spa store and I got a flat gasket (it matched the size of the flange exactly, and there was no o-ring groove). It still leaks, but a lot less. Any ideas? Call the manufacturer and try to get the original part? Replace the 90 degree elbow and flange to onw with an o-ring? Where do I get one?

[bevo]

Not a expert or anything, but if the flange on either side of the fitting is not smooth it wont seal. The bits of gunk need claening off.

[JOEY_G]

Not a expert or anything, but if the flange on either side of the fitting is not smooth it wont seal. The bits of gunk need claening off.

One is brand new, the other has been cleaned.

[Dnepr Dave]

Put a film of silicone RTV on both sides of the gasket and snug the fitting together, not too tight. Then let it cure overnight before you use it.

Dave

[JOEY_G]

Put a film of silicone RTV on both sides of the gasket and snug the fitting together, not too tight. Then let it cure overnight before you use it.

Dave

Dave,

I am not sure how your Caldera fits in the pump area, but mine is about 15 degrees off with no force on the flexible plumbing. If I had the fitting snug, it would allow the solicone to cure with a noticable "ramp" shape, since the pressure is higher at the back due to the alignment. I can try it like that, with the fitting mostly tight, and then wrench it after a 12-18 hour cure... maybe that will work.

I will be shopping for some waterproof RTV tonight...

[JOEY_G]

I just read at spadepot never to use a wrench on hot tub unions. Maybe I will not use one in the future...

[Roger]

I just read at spadepot never to use a wrench on hot tub unions. Maybe I will not use one in the future...

Get some majilube for the rubber gasket. Clean all mating surfaces. Go hand tight to start. Then use a strap wrench to get a little more until it stops leaking.

[JOEY_G]

I just read at spadepot never to use a wrench on hot tub unions. Maybe I will not use one in the future...

Get some majilube for the rubber gasket. Clean all mating surfaces. Go hand tight to start. Then use a strap wrench to get a little more until it stops leaking.

Majilube? Where is it sold? I can't find a product description or web page on the web.

Also, I found a gasket the same size that is called a "ribbed gasket". It is like a molded combo of a flat gasket and a o-ring. Sounds like a good way to use an o-ring without a gasket. Might try that too.

[simple]

Don't use silicone, get the magic lube, any pool supply place should carry it, it doesn't "set up" or dry. If all fails use petroleum jelly (vaseline), follow Rogers instructions. You shouldn't have to use a wrench accept to snug it, hand tight should be enough.

Making sure the red and black (in your diagram) are perfectly parallel before you start threading is key as well.

[quantumchromodynamics]

If all fails use petroleum jelly (vaseline)

Never use Vaseline on rubber gaskets. The best lube is Jacks 327 from Hayward. Jack's 327 lubricant is the same as Dow Corning's #111 Silicone lubricant. Aladdin Silicone Magic Lube II is also a good lubricant.

http://www.pfpros.com/pond-liners-aladdin.shtml

[Roger]

True never use anything other than approved o-ring lube Dow 111. Your problem is the o-ring/gasket and as soon as you get it you will say "that was easy".

Cool, the O-Ring store!!

[JOEY_G]

Thanks for all the replies everyone! I will go to the hot tub store and see if they carry dow 111 or an equivilent, and it they don't, I'm finding a new hot tub store!

[Hillbilly Hot Tub]

Also, we quite often see a union that will drip slightly untill the spa heats up, then it stops. We were told/taught that this is because quite often there are 2 different kinds of plastic, that exspand and contract, when the water is cold, one of them may contract more than the other. After it heats up, it expands and the leak stops.