How Best To Test
Dear RV Doctor:
In the past, you have said that a good RV technician would test a propane system at the main regulator using a propane testing device and manometer. The tests include measuring and setting the operating line pressure, verifying the lock-up pressure, and checking the coach for leaks. I have been told that RVIA technicians are taught to do these tests at the stove. Is that true?
Ann Martin
Orlando, Florida
Great question! We teach professional service technicians that it is permissible to perform the three propane regulator tests you mentioned anywhere in the system after the regulator. I specifically teach my students to perform them directly at the output of the regulator, for a few reasons.
First, some cooktops or ranges may be equipped with a third-stage regulator that, unless bypassed, will not allow for proper regulator adjustment. (The third-stage regulators are nonadjustable and preset to below 10 inches of water column pressure.)
Second, with the manometer at the stove or cooktop, the tech has to bounce back and forth, inside and outside the RV, between the regulator and the manometer to make the necessary microadjustments. It simply saves time and eliminates the hassle of bypassing a third regulator by having the manometer and test device attached directly to the output of the regulator. And, third, since the procedure allows propane gas to discharge from the test device, I believe it’s best to do that outside the RV.
So, succinctly put, my reasons for testing at the output of the regulator are that it’s easier, faster, and safer, with the added benefit of running all the tests at the same time. Otherwise, the process is the same.
Drive Belt Replacement
Dear RV Doctor:
I have a 2002 Fleetwood Discovery on a Freightliner chassis with a 3126 Caterpillar 330-horsepower engine. The radiator is rear-facing. Can the drive belt and the water pump belt be changed from underneath the coach, or must the master bed support be removed?
Ken Sherwin
Houston, Texas
I’m going to defer to Brett Wolfe, resident moderator on the FMCA’s online Forums (community.fmca.com). Here’s what he has to say:
“With a rear radiator, you will want access to both the top and bottom of the engine. Unless you have really long arms, it is difficult to get the serpentine belt over the alternator and fan hub from below. Be sure to replace both belts. The water pump belt is a standard V-belt on an old-style, manual-adjustment idler pulley. It is a Caterpillar part. The serpentine belt was specced by the chassis maker as they fit the alternator and air-conditioning compressor, so check with them for the proper one.
“If your engine (not coach or chassis) was built before January 2003, which sounds like it applies to your engine, be sure to grease the fan hub bearing (from above) while you are in there. It is just a standard grease fitting. It is a small bearing (actually, two small ones sandwiched), so do not overgrease. As with any belt change, it’s a good idea to spin each pulley by hand to make sure the bearings are good, which is really easy to do with the belt removed.”
So, there you have it, directly from the chassis guru! By the way, I encourage all motorhome owners to visit FMCA’s online Forums. You’ll find tons of good information there regarding just about everything motorhome-related.
Drilling Miscue
Dear RV Doctor:
I’ve had a 1984 Type A Winnebago Suncruiser motorhome for two and a half years and experienced no problems with the electrical system until recently. When I plugged the shoreline cord into the 120-volt outlet, the black wire on my DC panel overheated and started to melt. It doesn’t overheat if I unplug the converter/charger. I didn’t have this problem until my husband drilled a hole into a square tubing that goes up the wall and across the ceiling; he was connecting a bracket to secure a refrigerator while we are on the road. Are there DC wires going through the tubing? Is it possible that he put the screw into the wiring, and now it is grounded?
Brenda Mayberry
Via email
It is possible the drill hit some electrical wiring. But I’m surprised no breakers were tripped or fuses blown. I’m not 100 percent sure that the Suncruiser has hidden conductors, but it’s very likely, since that is one of the easy ways to route the wiring harness and cables.
In the shop, rather than try to locate the actual spot of the fault, it’s easier to simply run a new section of wiring, bypassing the problem area altogether. Since the problem is manifested on the DC power side, I’m guessing the faulty section lies somewhere between the converter and the DC panel on the battery charge line. There is a chance the charging module in the converter/charger has been damaged by the possible short, causing a high degree of overcharge. It is important to totally de-energize the converter/charger during the troubleshooting phase. Any certified RV service technician can make the repair.
Though unfortunate, it’s not the end of the world. This happens often and is repaired easily enough by cutting that wire at both ends, safely taping them off, and then routing a new, like-sized conductor the easiest way possible.
Exterior Lamp Lacking
Dear RV Doctor:
Do you know where I can find an instrument panel wiring diagram for a 1996 Damon Challenger Type A motorhome built on a 1995 Chevrolet P-30 chassis? I can’t find one anywhere. I have one loose wire that affects the exterior lights, which means I can’t drive at night.
Thomas Peters
Via email
All wiring for the exterior lamps — headlamps, turn signals, running lamps, etc. — comes off dash switches. The turn signals are pretty straightforward, but RV makers often modify the wiring to suit their construction techniques. The headlamp switch (which also powers the trim marker lamps) is often spliced into the circuit somewhere near one of the forward corners. A harness usually runs up in the front and another along the frame rails to the rear, then up the back cap to all the clearance markers.
Damon could have spliced the clearance circuit just about anywhere. If you can, trace the wiring harness from the switch or, better yet, find the conductor coming down from the clearance lamps and simply splice it into the headlamp switch circuit. It’s probably a deteriorated crimp/spade connector or butt splice somewhere between point A and point B.
In the shop, I’d spend about 45 minutes trying to find the broken connection, then about 15 minutes running a new wire. So, the find and fix would take about an hour. But it does require some troubleshooting. If any of the clearance lamps are working, the problem lies somewhere between them, usually up inside the cap.