Stubborn Leak in Shurflo Vac Box

[SeanD]

I've had a stubborn leak in a vac box that I think I've pinpointed at the threads of the filter housing - or maybe the filter housing itself - or maybe the fitting that goes onto the filter housing from the line in - or maybe all three - or maybe all three of those and some other spots, too. Ok, I've basically got the leak nailed down to somewhere in the vac box.

In order of easiest fixes first, I'm going to check the threads on the filter housing and re-tape them. I'm only going finger tight, but it seems like it's still too easy to turn. Any harm in putting 3,4,5, or more turns of tape on there to snug it up? Seems a bit Mickey Mouse - but if it works...

I'm recirculating water through the pump. When I apply some side pressure on the filter area, I get the vac to jump from 5-8" to about 17". That's obviously a big improvement, but is it optimal? What's the best vac I could hope to pull recirculating water through a Shurflow. If It's 17" then I have one leak and I've found it. If it's 27" I'm rebuilding the whole thing!

Thanks,
Sean

[softmaple]

try a little of this stuff on your tape

https://rectorseal.com/product/rectorseal-tru-blu/

[Biz]

The amount of vacuum you can pull on a Shurflo recirculating water (assuming no leaks) depends on what you have for intake restriction. If you are using a half inch hose, your vacuum will be very low. Reducing to a 3/16 line on the inlet you should get 15-20". Pinch the flow off a little more with a needle valve or maybe a vise grip temporarily on the line and you should get 25" of vacuum after a couple minutes. That's what I test all my systems to. If you have a leak, try pressurizing it with an air compressor fitting and run some water around the joints and look for bubbles. Tough to find a vacuum leak in the piping but easier to find a pressure leak.

For sealing pipes there is another product "Gasoila" available online or at plumbing stores like FW Webb around here.

Dave

[Russell Lampron]

In order of easiest fixes first, I'm going to check the threads on the filter housing and re-tape them. I'm only going finger tight, but it seems like it's still too easy to turn. Any harm in putting 3,4,5, or more turns of tape on there to snug it up? Seems a bit Mickey Mouse - but if it works...

Thanks,
Sean

If I'm reading this correctly you're only tightening the fittings finger tight? If so you need to tighten them with a wrench. All you need is three wraps of Teflon tape on the threads.

[whity]

We have had problems with filter housings crack in extreme cold weather. We run 4 Shurflo pumps in our woods. Wrap all fittings with Teflon tape and tighten with a wrench. But I would check to make sure there are no cracked fittings or filter housing. On average we are getting 20 inches of vacuum per pump. Any less the 15 and there is a leak

[maple flats]

On most threaded fittings, if the threads on both halves are good you want 3 wraps, or 3.5. Every once in a while you will come across a fitting where the female thread is slightly large, needing an extra wrap but in 1/2" I've never seen it happen. Use a wrench, but don't be too forceful, teflon tape has lubricating properties and you could damage the female part if over tightened. I suggest (I was a plumber for 20 years) if you have a leak, remove the old teflon tape, wrap new on 3.5 turns (when you buy the tape, buy good quality tape, not harbor frt stuff) then turn it in finger tight, then use a wrench and add 1 more turn.
To be honest, teflon tape should not be used on plastic fittings because of the ability for it to cause the female part to split, that being said, I often use it. A good teflon thread seal compound (paste) is better to use. The Rectorseal Tru Blu linked to above is good stuff, available at most plumbing supply houses (where the pros shop), maybe not at Lowes or Home Depot. Likely Amazon has it.

[SeanD]

Thanks for all the feedback. I think I got it. I disassembled and cleaned the threads up well with a toothpick. There were bits of tape and crud that may have been part of the problem. I was going finger tight on the plastic pump and filter housing fittings because they just seem so fragile and the filter cup itself says only finger tight on it, so I just carried that idea over to the inlet and outlet. I'm still finger tight, but I did go a little tighter.

That said I used new tape - the blue monster stuff. I can't remember the exact name right now. The vac gauge sits at 19" and I can push it into the mid 20s if I pinch the inlet tubing. Thanks for that idea, Dave.

Two things came up, though. The needle on the gauge shakes something fierce. +/- 1". If I held the gauge in my hand or supported it with a piece of scrap wood it settled down a bit. The gauge in my other box doesn't do that. This one did it when there was a leak, though. Do others get that?

The other thing is the filter cup faces up when it's tight against the pump. I backed it off a half turn to get it to point downward. I'm a little nervous about using a wrench on that last half turn the other way to get it downward. With the 19" I'm wondering if I should be happy as is.

By the way, one plug for avoiding freezes in the filter and pump is that I use Mountain Maple's S3 unit that drains the line before shutting off at the low temp I set. I highly recommend it for your remote setups.

Thanks again for the input.