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Water Leak

June 11, 2012, 03:37:11 pm

After replumbing the water pump in my 280 I have a small but persistant and ( intermittent water leak.)
After looking for three days at various times I finally found the leak with just dumb luck.
Behind the water heater is the overflow tube from the tank,  The tube goes UPHILL and then crosses over the tank and exits in front of the LR wheel and aft of the bulkhead.  Only when I fill the tank and water sits in the overflow before I drive off does the tube leak right near the connection to the tank.  Repairing it is going to entail pulling the water heater and replacing/repairing the overflow tube.
While I sit and ponder this job I think what I will talk myself into doing is replacing the overflow and routing it overboard thru the floor as some others have done.  From all appearances the leak is in the tube itself in one of the coils which means replacement anyway. I know of no reason why this tube is as large as it is, it is about 1 1/2 to 2 inches and I think that a smaller tube would work just as well.
If anyone has another solution I am open to it.
Gary B

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Reply #1 – June 11, 2012, 03:55:07 pm

Gary,
I would do the same and in fact this is one of the projects on the Forrest to-do list.  I would think that a hose the same diameter as a garden hose would do the trick as the overflow is caused (sometimes) by overfilling the tank with city water.  Then the pressure into the tank from a city fill can be handled by an equal size hose at the overflow.
Peter

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Reply #2 – June 11, 2012, 05:55:12 pm

We had a similar over-flow fitting leak up behind the water heater. We just put a towel down on the floor and did not fill tank to top. And then one day we decided to replace our original water heater with the later style with electric heater built ink. When we had our hot water tank out, Replacing a Water Heater we ran new green & white RV water fill hose, which was the same diameter as our original hose, over to behind the holding tanks and then down through the floor under the manifold to keep the overflow water off the bulkhead.

This overflow hose is also the air vent hose for the fresh water tank. There is no good reason to run a smaller diameter hose which could pressurize the tank during filling. The overflow hose must be larger then fill hose to prevent pressurization. And the green water fill hose is available in RV parts departments and comes in 3 diameters, so bring your original to match a new hose. Air and water must freely move in the overflow hose.

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Reply #3 – June 11, 2012, 07:21:56 pm

Barry, My only thought about size of overflow tubing was that a smaller hole could be cut in the floor of the bay.  I will probably not tackle this for a while and in fact a good time to do it would be with a water heater.  My WH is still working well.
Gary B

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Reply #4 – June 11, 2012, 08:28:09 pm

Gary, I had a very similar intermittent leak. In my case it turned out to be leaking from the tank wall itself, and like your's only when the tank was full. See attached photo.
Does anyone know why that overflow hose runs uphill, then down, and then back up? Is it supposed to be like a P-Trap and hold water in there to prevent some kind of contamination or something? I frequently hear it gurgling. Since it's the only vent, it will gurgle when filling and when emptying. I wonder if it would be ok to take that dip out?

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Reply #5 – June 12, 2012, 07:54:13 am

Dick, That may well be the source of the leak,  With full  tank I can see thru inspection port behind WH that there is a drip on the overflow tube.  I will have to take the WH out to see for sure and in the meantime it is really annoying.  For the time being I will keep the water level lower and see if that will keep water out of the tube.
Gary B

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Reply #6 – June 12, 2012, 08:57:49 am

FYI, I was in Harbor Freight, and noticed they had a remote camera on a wand, and screen system for hidden area inspections.  Was on an end cap and did not notice the price.  But it might be worth the money to be able to inspect and investigate places before tearing into them.  My mechanic friend has one in the shop and uses it all the time for behind components inspections.

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Reply #7 – June 12, 2012, 11:53:04 am

Dave, That would be useful, I'll check next trip to Harbor Freight.  Thanks
Gary B

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Reply #8 – June 12, 2012, 05:12:14 pm

I modified the two fresh water tank bottom 0.5" hose connectors and the top 1.62" vent.

The intent here was four fold:
Firstly; to stop dumping fresh water on the bulkhead when driving or filling.
Secondly; to have a 1.5" vent available when filling the fresh water tank.
Thirdly; to have a filtered (near the bathroom ceiling) 0.5" fresh water tank vent.
Fourthly; to have a clear water level site tube outside, near the fresh water tank.

I removed the original vent tubing which had a spiral reinforcing bead on the outside. This bead made it very difficult to get a good seal with a hose clamp. I purchased 2 feet of 1.62" clear vinyl tubing at Home Depot, which was heated to soften and actually sealed on the tank vent fitting without a clamp, but I did clamp it. This new vent tube goes straight toward the passenger side of the motorhome and touches the dividing wall between the gray tank and the fresh water tank. I cut the tube to length and installed  a 1.5" plastic ipt "T" with the "T" pointing up. 

The in board end of the "T" is connected to the vinyl vent tube from the tank, while the outboard end has a 1.5" inch plug. The "T" connector pointing up is reduced to 0.5" with brass adaptor. Half inch copper tube is attached to the brass adaptor and is run in the cabinet behind the toilet to terminate at a small pastic tank in the bathroom upper cabinet (near the bathroom ceiling).

For the site tube: a copper 0.5 inch tubing "T" was installed in the 0.5 inch copper vent tube for the top while the original tank drain was used for the bottom of the site tube.

For a fresh water tank drain: the original fitting in the bottom of the tank which connected to the water pump was modified by making the "90" into a "T" and connecting a new line for a fresh water tank drain.
     
I did this work without removing the water heater by working through the access hole in the 6 foot storage bay, behind the water heater. Awkward, but it can be done.

I also installed a hot water bypass for the kitchen sink.

By the way, the small plastic (see through) tank in the bathroom was installed in case water ever gets to that point. I had no idea how far up the vent tube the water gets when driving - so far this tank is dry.

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Reply #9 – June 12, 2012, 08:36:54 pm

Actually making a hole in the floor of our bays is pretty simple as most of the floor has thin fiberglass-type of material top & bottom with Styrofoam in between. Anything we put through the floor is silicone on top and bottom.

We decided to do our water heater before it gave up the ghost by leaking, etc.  And it gave us a chance to plan and redo ALL plumbing between freshwater tank and manifold. We ended up removing two hoses that went to bottom of bathroom cabinet because we use a gravity feed directly to the top edge of our fresh water tank for filling tank with city water.

We also ran hot water tank in and out hoses to the water manifold so we could close them off and bypass the hot water tank if desired. Another mod we did was to put a ball valve on the in & out lines connecting the water pump, so we can change water pump without making a mess, draining freshwater tank and manifold.

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