The faucet in the kitchen sink didn't work great when we bought the RV, then it stopped working completely. I decided to replace it. I went to a box store and picked up a single hole kitchen sink. Turns out that the hole in the sink was too small. No problem, a couple minutes with a grinder solved that.

Then I went to hook up the water lines under the sink. Turns out that my 1977 GMC Motorhome uses polybutylene pipes. I never thought much about the gray plastic water lines in this old RV. I figured at some point the pipes were changed over to some early color of pex. Nope! GMC was ahead of their time when they used this cutting edge plastic pipe in the RV. Most sources say PB pipe was introduced in 1978. Regardless, this stuff was eventually known to fail quickly and without warning. After a bunch of lawsuits in the 1980's no one uses this stuff any more. Granny Smith appears to have the first iteration of the PB pipe because all the fittings are also PB and screw on, rather than clamp on or brass.

The PB pipe will need to be replaced but that is a job for another week. There are places that sell adapters to go from PB to copper or pex. Of course no one had any locally in the 3/8" since I needed. I was going camping the next day and needed water so I ghetto rigged some flexible rubber line in there. Don't judge me. We didn't use the water for drinking, just washing dishes. And of course, without the faucet in place I couldn't turn on the water pump, so I would have not had a toilet or bathroom sink either.

After I got the kitchen faucet in and working I found that the water pump was running regularly, even when no faucets were open. I traced the problem to the water heater. The pressure relief valve was busted and allowed water to trickle out. That trickling water would normally go down a tube, thorugh a bulkhead fitting, and out into a wheel well to fall harmlessly on the ground. Not in Granny Smith though, no. The bulkhead fitting was completely corroded and snapped off. As a result, the rubber hose from the safety valve was just dumping water onto the top of the fiberglass wheel arch. The water then ran under the bathroom floor and into the hallway carpet. What a mess!

I replaced the safety valve and the plumbing so that the water safely drains out the wheel well.

Preview Image Size Thumbnail Small Medium Large

Smll Med Lrg old faucet was completely broken	Smll Med Lrg	Smll Med Lrg compression polybutylene fittings, this is a problem	Smll Med Lrg can't get PB adapters locally. I just cut off the old faucet supply to keep the old pb adapters
Smll Med Lrg	Smll Med Lrg 3/8" polybutylene lines, ugh	Smll Med Lrg	Smll Med Lrg
Smll Med Lrg mounting hole is too small	Smll Med Lrg now mounting hole has been enlarged	Smll Med Lrg the drains are gross too. I will replace them with a bathroom sink drain for now	Smll Med Lrg new faucet looks great
Smll Med Lrg Not much room under sink for extension, but a few inches is still nice to have	Smll Med Lrg	Smll Med Lrg my ghetto adapters to merge polybutylene to 3/8 compression fitting	Smll Med Lrg don't judge me. This was not used for drinking water, temporary fix for next day's camping trip
Smll Med Lrg	Smll Med Lrg looking much better,	Smll Med Lrg sunlight visible where bulkhead drain fitting should be	Smll Med Lrg tube in foreground was draining onto top of fiberglass wheel arch
Smll Med Lrg	Smll Med Lrg	Smll Med Lrg	Smll Med Lrg
Smll Med Lrg	Smll Med Lrg	Smll Med Lrg	Smll Med Lrg
Smll Med Lrg	Smll Med Lrg both of those bulkhead drain fittings are junk	Smll Med Lrg	Smll Med Lrg
Smll Med Lrg	Smll Med Lrg	Smll Med Lrg	Smll Med Lrg temporary fix to get safey valve slow leak water draining out of the RV
Smll Med Lrg ok, at least water is no longer collecting under the carpet inside the RV	Smll Med Lrg the source of the leak was the safety valve	Smll Med Lrg	Smll Med Lrg
Smll Med Lrg not shown; reinstalled rubber drain lines	Smll Med Lrg topped off coolant tank only to have coolant immediately drain out	Smll Med Lrg HUGE crack in old tank	Smll Med Lrg had to loosen AC thingy-ma-bob to get coolant tank out
Smll Med Lrg	Smll Med Lrg they still make tanks for this RV. Thats cool