Solved: How to find vacuum leak in water supply line?

[joerg68]

Hi all,

this week we picked up our new camper, a Northstar Arrow.

The camper is fantastic and we are very happy with it - except for one problem with the water supply that has us all stumped:

The water pump does not provide constant pressure, sputters, and frequently loses prime. It seems to suck in air somewhere. Especially when we take just a little bit of water, it tends to lose the vacuum and runs dry until we take a lot of water again. Then it primes and works, but sputters frequently. The issue is a bit better when the tank is full, and gets worse as the tank empties.

What we have done so far:
- Checked the tank vent hose - it is free, no kinks or obstructions
- There are no water leaks, anywhere. It holds pressure fine on the pressure side
- All fittings are firm to the touch and dry from tank to pump
- We have switched the winterizing valve and sucked water through the winterizing hose. The effect remains the same.

This would put the problem somewhere between the winterizing valve and the pump (including both), right?

Anyone have an idea how to find the vacuum leak short of disassembling the whole water line from tank to pump? It is made up of around 8 or 10 short sections of solid plastic pipe. And a number of elbows and the one winterizing valve. You can not see if and where any bubbles are introduced. The strainer is installed with the clear lid facing away from us...

To make matters more interesting, we are still on our shakedown trip and have no useful tools with us.

What would you do to find the leak?

[joerg68]

Google for "deck plates for boats"

Took me a while, first in german, then english.

[SidecarFlip]

woodhog wrote:
While on your Northstar water adventure you might consider this mod:


Easy access to the tank to work on it, easy to clean out the tank and
also you can fill it from the inside, or even dip water out if your
plumbing fails.

Woodhog... Where did you get that..Lowes maybe? My tank is also exposed and I can do that as well...

[joerg68]

Allright, finally got it all solved. Replaced the strainer.

The original strainer was a one-piece unit that you just screw on, part number ending in 213/313.
It had the added downside that the clear strainer lid was facing to the wall when mounted on the pump.

There is an alternative model number ending in 215/315. It comes with a nut and can be mounted at any angle. So now the clear lid is facing the door. The replacement screwed on in 5 minutes and everything works fine now.

The old strainer for some reason did not achieve an airtight connection at the pump side. Whatever, it works now and we are happy. Not only can I now replace these things blind at 3am, I even know the part numbers by heart.

Thanks to everyone who answered!

[joerg68]

Hi woodhog, we have been thinking about this. Easily done on this camper, and no more doubts about what might be inside the tank 😉 Thanks!

We have now ordered an extra strainer to see if it makes a difference. I'll update in due time.

[woodhog]

While on your Northstar water adventure you might consider this mod:


Easy access to the tank to work on it, easy to clean out the tank and
also you can fill it from the inside, or even dip water out if your
plumbing fails.

[joerg68]

Some Teflon tape between strainer & pump may have mostly solved it... we shall see tomorrow. Still surprised that there should be no gasket between strainer and pump.

Thanks so much everyone! Great help here!

Joerg

[Kayteg1]

Compression fittings on vacuum are hard to troubleshoot (unless you have Cuban, that is) but in case of doubt - put some teflon dope on it.

[joerg68]

Hi everyone,

so we are back home and testing.

Should there be any type of seal or gasket between the strainer and pump?

Strainer looks like this, screws directly onto the pump inlet as one unit: SHURflow RV MARINE Water Pump Inline Stainer Filter 255-213 / 255-313

There is no seal there, just hard plastic flanges. Is that correct, or is there something missing? Reassembly with vaseline briefly fixed the symptoms, which may mean I am looking in the right places...

[Bedlam]

Since this problem happens with the tank or bypass, it is a problem with the pump head or pre-filter. You should be able to disassemble the pump and check the seals and valves.

[joerg68]

So we are still on the road with the vacuum leak. After all, it is a TC and don't they all have their quirks...

Re. warranty issue: yes, it sure is. But the effort in time and money to take it to the dealer is not worth it, and travelling with an American made RV in Europe has tought us to be self-reliant. I am sure the dealer would send a new pump if the old (still new) one turns out to be defective.

When we get back home I will see if I can provoke a water leak from the winterizing hose side. And then I will probably do some disassembly and cleaning and reassembly. It is a new camper, I need to get to know it inside out, right? 😉

If that doesn't fix it, I need to find a local shop who is willing to take a look.

Thanks for all the feedback and I'll keep you posted

[unbob]

I had the exact same problem! In my case it turned out to be a worn-out 'O'-ring on the strainer housing. Or it could be the strainer "cover/cap" is not screwed-on tight enough. There was no water leakage - only air being sucked-in. I would check this before proceeding with other troubleshooting.

Also, the 'O'-rings on the inlet & outlet hose fittings on the pump can also eventually "give-out" and cause a water leakage (been there/done that!) - so good idea to replace those every 5-6 years as easy preventive maintenance.

[jimh406]

I think I'd talk to the dealer as well. It's brand new ... it should just work assuming the holding tank has enough water to pick up water and the winterizing switch if equipped is in the right position.

[mkirsch]

I know it would be somewhat inconvenient, but that sounds like a warranty issue to me.

[midnightsadie]

my strainer bowl had a crack and acted like this.