Sink Drain Pipe Broken

[JerArdra]

7/7/05

All,

This involves the kitchen sink drain pipe on a kitchen slide out MH.  Mine broke!  The attached photo shows the looped 1-1/2 inch flexible drain line when the slide is extended.  The problem is that when the slide is retracted (closed) the area where the arrow is would move toward you as you are looking at this photo (this is toward the center of the coach).  During that movement the the loop at the top gets shorter and there is a tremendous pressure pulling down on the flexible pipe where I marked with the arrow.  Over time this results in tearing the flexible pipe and thus a leaking drain line.

One solution is a more flexible 1-1/2 hose but you do need some rigidity so the loop moves smoothly as the slide moves both in and out.

Another solution would be a flexible joint that would interconnect the flexible pipe to the hard ABS plastic sink drain line in the area whee I have the arrow on the photo.

I have two questions (this is a drain line so there is NO pressure)...

1.  Does any one know of the 1-1/2 inch flexible pipe joint.  What I picture is a connector that would interconnect where the flexible pipe joins the hard plastic ABS sink drain pipe and that also has a ball joint in the middle so it can flex downward 20-30 degrees when the slide is retracted in.  For example, if you were holding your hand palm down and the bent you index finger down it would flex at the first joint.  All you need is about a 20 degree downward flex so as the loop gets shorted and begins to pull downward on the flexible hose there is less downward pressure on the flexible hose.  Also when you again extend the slide the flexible joint would go straight for draining.

2.  Any other ideas?

Thanks to all,
JerryF

 

[Karl]

Jerry,

Is that a 90 degree ABS elbow that's connected to the flex tube? If so, what's the inside diameter of the tube where the elbow goes in?

 

[JerArdra]

Jerry,

Is that a 90 degree ABS elbow that's connected to the flex tube? If so, what's the inside diameter of the tube where the elbow goes in?

Karl,

Yes, it's a white schedule 40 90 degree fitting.  A standard Schedule 40  1-1/2" plastic pipe fits the inside diameter of the 90 so the "actual" inside diameter is 1-15/16th " because of the pipe wall thickness of the schedule 40 1-1/2" pipe.  But in this case, it's a 1-1/2 inch flexible hose (like the one in the photo).  It's just that the outside diameter of the flexible 1-1/2" hose is identical to the diameter of a schedule 40 1-1/2" pipe.  The flexible tube is 1-15/16ths" outside diameter.

JerryF

 

[Karl]

Jerry,

If you look under the sink, there should be a vertical pipe coming from the 180 degree trap going to the drain tube of the sink. It uses a compression-type coupling with a beveled nylon washer (seal) to grasp the drain tube. Seems like an adaptation of this type of coupling, with the compression nut left slightly loose but prevented from unscrewing itself, might do the job. The seal may not be watertight, but it doesn't really have to be.

 

[JerArdra]

Jerry,

Seems like an adaptation of this type of coupling, with the compression nut left slightly loose but prevented from unscrewing itself, might do the job. The seal may not be watertight, but it doesn't really have to be.

Karl,

Interesting idea!  I'll look at that idea and see what I can do.  BTW, I did fix it but it was fixed just the way Monaco installed it in the first place.  What I am doing now is trying to find better ideas in case it fails again.  I have already found a similar problem on Newmars.  Someone else told me Newmar now has some sort of flexible swivel fitting.

Thanks,
Jerry

 

[Ken & Sheila]

Jerry,

I really think that if the Flex hose was 2 to 3 inches longer you wouldn't have a problem. But now that you've had the problem I guess I better look at mine and make sure it is not about to break. I know there is some stress because it actually moves the drain pipe under the sink. Used to cause leaks when the slide was in, but I fixed that with a flexible piece between the sink and the "P" trap.

Good luck

Ken

 

[Jim Dick]

Jerry,

Mine did exactly the same thing on the Dream. When the slide was in the pipe was completely collapsed. I never realized it since we normally don't use the sink without the slide extended so wouldn't notice the sink not draining properly. I fixed mine by extending the flexible pipe by a inch or so. This allowed the slide to come in and not pinch the drain. We'll see how well that works. The other one lasted 5 1/2 years!

 

[Gary RV_Wizard]

Ours broke at the Tee where the flex line connects to the Schedule 40 pvc pipe. Actually broke the tee as a result of the pressure applied each time the slide was closed.  I added about 12 inches of flex line to relieve the pressure.    It would have been a major (read factory) job to get at the schedule 40 tee for replacement, so I just broke off the jagged pieces of the tee and sealed the end of the flex line into the remaining hole with caulk. It has been holding for two years now.  I also routed the flex line and other lines (water and electric) a bit better and secured them in place so they move nicely with the slide.  The design was OK, but the installer simply had not paid enough attention to tolerances at full extension and full close.

 

[Karl]

Gary's idea sounds like an easier and less costly way to get the job done. I keep forgetting the KISS principle ;D

 

[JerArdra]

All,

Mine is fixed now but I wonder if it might occur again; therefore, using careful measurements I determined that for every inch of inward slide movement the u-shape curve of the flexline moves toward the center of the coach 1/2" so with only 1-1/2' of space until the loop would hit the wall I could only lengthen the flexline by 3 inches.  This is tough to do because the connectors to do this are NOT flexible.

OTOH, I did come up with a simple way to try to reduce the downward pressure that is breaking the flexlines at the top connector.  I tested and probably will install a wedge the raises the lower portion of the looped flexline by 2-1/2 inches when the slide is in.  See photos.

The wedge pushes up on the loop forcing the loop to take more of the bend thus reducing the downward bend at the upper connector.  BTW, on mine, there is no more upward bend pressure at the lower connector because the flexline becomes longer on the bottom of the loop as the slide moves inward.  Also I can see that the the wedge is NOT lifting the flexline up at the bottom connector.

Any comments appreciated.  ???  ???

JerryF

 

[Tom]

Jerry

You're one resourceful guy!

 

[Karl]

Looks good, Jerry! ;D

Only suggestion I would make is that you make the wedge the full width instead of using the spacer, to eliminate the possibility of chafing or the flex tube getting wedged in accidentally.

 

[Bob Buchanan]

Hi Jerry:

>> 2.  Any other ideas?
====
Am reminded of the Hee Haw doctors office skit - whereas the patient complains that his arm hurts if he raises it above his head. The doctor thinks a bit, and then solves the problem by advising, "Well -- just don't raise your arm anymore". So my advice is to not extend the slide anymore

Interesting in all the responses from those with kitchen slides that this problem exists across so many different manufacturers.

Yes, Tom, my good friend Jerry "is" a very resourceful dude. If one happens to break down, they can consider themselves very lucky if Jerry happens to be near by. A few months back, I broke down near Las Vegas. Within a day or so, Jerry saved my cookies and had me back on the road in good order.

 

[JerArdra]

Looks good, Jerry! ;D

Only suggestion I would make is that you make the wedge the full width instead of using the spacer, to eliminate the possibility of chafing or the flex tube getting wedged in accidentally. 

Karl,

Good observation Karl, you're good, but the extra space is because Monaco has a plastic channel to guide the hose in a straight line (see original photo) so I must live with that.

Because of this, one further modification I will make will be to move the wedge to the left (toward the center of the coach) so the flexhose stays in the plastic channel as long as possible to ensure that the hose tracks straight as the slide is closed.

Still another idea!  Today I hope to visit a swimming pool parts supplier.  The hose that is used to vacuum the bottom of a pool is a 1-1/2" hose that is MUCH MUCH MUCH more flexible (it can easily bend down 20 degrees) than the flexhose used by motorhome manufacturers.  MH manufacturers may not be able to use a swimming pool hose because of the RVIA building codes but I could, that is, if mine breaks again.

I am still testing a flexible fitting that can bend down and would be RVIA approved.  I will report shortly.

JerryF

 

[John From Detroit]

I do not know if this trick will work for you (Depends on among other things hole size)

But several years ago my parent bought a new washer, dryer and "Suds Saver" tub for our laundry room... Of course the drain pipe did not match up... Back then flexable drain pipes were... Well... NOT.. So McGuiver that I am I visited the gararge and came up with an 1 1/4: ID (This was the pipe size) Radiator hose.  Worked great

IT was at least a decade before it rotted out.. (IT won't last as long as PVC)

These hoses are designed to handle chemical laden water at tempertures above 200 degrees and not burst so a bit of dishwater is no problem for them.

ALso, several rigs are plumbed with flexable tubing you can pick up now days at most any hardware store, comes in assorted sizes and colors

The problem is this... If they put the PVC pipe through a hole somewhere..... You may have to re-drill the hole larger to accomadate the flex tubing or radaitor hose.

 

[JerArdra]

Radiator hose.  Worked great.

That is a good idea.  A short piece of Radiator hose and clamps could
be used with the following idea instead of Braided PVC flex hose.  The
problem is that it would not meet the RVIA standards for drain lines.

Here is an idea for the NEXT time mine breaks.  Make a solid but flexible
joint that has the ability to bend down about 20 degrees when the
slide is in and still go straight when the slide is out.  The current
white flexible PVC hose used today does not do this adequately.  This
bending would relieve or eliminate the possibility of the somewhat
stiff white PVC flexible pipe from tearing at the upper connector.

This so called ?fitting? that I conjured up is stiff enough to push
the loop as the slide comes in and, as the same time, it can bend
downward 20 degrees easily.  I estimated that when the slide is in and
it is bent downward the 1-1/2? diameter probably is reduced to about
the size of a ?? to 1? pipe.  This should be no problem in that when
the slide is in you do not run lots of water through the kitchen sink.
  I ran tests, using PVC cement, on the joint between the clear
plastic pipe (Braided PVC) and the white connector.  This joint cures
slowly so the joint should be set and then wait 24 hours before using
it.  Furthermore, I suggest full size connectors because they have a
1-3/8? depth so there is more contact area between the connector wall
and the braided PVC pipe for the PVC cement to weld them together.
The narrow connectors currently used only have ?? inch of contact
depth.  I used transition cement between the white and black plastic
parts.

With regard to the photos, on the left end of the 1-1/2? ?PVC Braided
plastic pipe? is a 1-1/2? white coupling that joins the white PVC pipe
currently  used.  This is the bendable joint.  On the right end is a
1-1/2? 90 degree street ell.  The 90 degree street ell has a 1-1/2?
black ABS coupler that connects directly to the 1-1/2? black ABS
horizontal sink drain pipe that comes from the sink trap.  I used a 90
degree street ell instead of a 90 degree long turn elbow because I
wanted to shorten the distance that the solid pipe protruded toward
the center of the coach.  Shorter is better because when the slide is
in there is not much space between the solid pipe and the inner wall
of the MH for the flexible pipe to make its 180 degree loop and that
is the crux of the problem.

For example, the closer the solid pipe is to the inner wall, the
tighter the loop will be, and the higher the probability that the
flexible pipe at the upper connector will tear at the connector.  The
street ell drains perfectly well.  It?s fast.  Houses use 90 degree
long turn elbows where space is no problem, 90 degree street ells are
fine for MHs.

Another solution might be to use the PVC Braided 1-1/2? hose in place
of the less flexible white PVC hose.

For now I am sticking with fix I did and the 2-1/2" wedge described earlier.
The fix I did was to use a 90 degree street ell as described above. 

That's it folks, I'm fresh out of ideas!!!  ;D ;D

JerryF