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Ryan7361 · 08-22-2015, 05:15 PM

I have a typical ASME propane tank under my rig, and the gauge suddenly stopped working. It was 3/4 full at last check. It is an old needle gauge in the dash(1987). I push a button when the key is in the ignition and the needle jumps to current propane level. Starting today nothing happens!
What is the most common cause of this? Switch, gauge, or sending device?
Also, I replaced the regulator this March.

BFlinn181 · 08-22-2015, 05:34 PM

I'd start by checking the wiring back near the tank. Perhaps in changing out the regulator you dislodged or broke a connection. Often with the electric gauge there's also a mechanical gauge attached to a float in the tank.

mgscott4 · 08-22-2015, 08:26 PM

fuse?

cimplexsound · 08-22-2015, 09:03 PM

I have the same problem. Propane sensor does not work. Over time the sensor freezes up and they stop working. If its not the wiring as other have mentioned. Test the gauge itself. If that's not it then probably have frozen sensor.

1979 Dodge Tioga Class C 24 foot. 1987 Fleetwood Bounder 34 Foot.

KIX · 08-22-2015, 09:19 PM

Quote:

Originally Posted by Ryan7361

I have a typical ASME propane tank under my rig, and the gauge suddenly stopped working. It was 3/4 full at last check. It is an old needle gauge in the dash(1987). I push a button when the key is in the ignition and the needle jumps to current propane level. Starting today nothing happens!
What is the most common cause of this? Switch, gauge, or sending device?
Also, I replaced the regulator this March.

The gauge (dial) at the tank will have an electrical connection. You may need to just clean that connection. The dial is held in place with two small screws. The dial is moved by a magnet and the dial itself does not actually touch the propane in the tank. You can remove those two small screws even if the tank is full of propane. A propane dealer should be able to sell you a new dial. Be aware that the dial is matched to the electrical gauge and is of a specific ohm value. Make sure the new dial is the same ohm rating zs the old one.

cimplexsound · 08-23-2015, 03:40 PM

Like Kix said. Make sure the propane tank is empty. Use WD-40 to loosen the screws holding the sensor to the tank. Turn all power to the sensor off. You might need a breaker bar if the sensor has never been removed. They put a lot of torque on the screws when they do the installation in the factory. It is either a pressure sensor or a floating mechanism. Clean with WD 40 being careful not to short circuit electrical parts or wires. White lithium spray is the perfect lubricant to use before reinstalling. Use it sparingly and only on the mechanical part of the sensor. Replace the rubber gasket. If it is cracked replace it to avoid propane leaks. Then reinstall with the screws being nice and tight. Now hopefully the white lithium will keep it working trouble free for many years.

1979 Dodge Tioga Class C 24 foot. 1987 Fleetwood Bounder 34 Foot.

ga traveler · 08-23-2015, 04:07 PM

Quote:

Originally Posted by cimplexsound

Like Kix said. Make sure the propane tank is empty. Use WD-40 to loosen the screws holding the sensor to the tank. Turn all power to the sensor off. You might need a breaker bar if the sensor has never been removed. They put a lot of torque on the screws when they do the installation in the factory. It is either a pressure sensor or a floating mechanism. Clean with WD 40 being careful not to short circuit electrical parts or wires. White lithium spray is the perfect lubricant to use before reinstalling. Use it sparingly and only on the mechanical part of the sensor. Replace the rubber gasket. If it is cracked replace it to avoid propane leaks. Then reinstall with the screws being nice and tight. Now hopefully the white lithium will keep it working trouble free for many years.

1979 Dodge Tioga Class C 24 foot. 1987 Fleetwood Bounder 34 Foot.

I believe you are misunderstanding Kix. He is talking about the gauge on the tank. It is only external and does not go into the tank. The tank can be full of LP and it does not matter. The gauge is a magnet and steel setup. there is no tank intrusion. (As Kit said.) Most of the time we lost contact it was the gauge or the ground. There is only one wire going to the gauge and then the gauge goes to ground.

BFlinn181 · 08-23-2015, 04:57 PM

Quote:

Originally Posted by ga traveler

I believe you are misunderstanding Kix. He is talking about the gauge on the tank. It is only external and does not go into the tank. The tank can be full of LP and it does not matter. The gauge is a magnet and steel setup. there is no tank intrusion. (As Kit said.) Most of the time we lost contact it was the gauge or the ground. There is only one wire going to the gauge and then the gauge goes to ground.

I agree, Kix said the tank DIDN'T have to empty, he said, "even if the tank is full of propane." Kix was talking about the electric sensor that measures from the magnetic needle of the mechanical gauge attached to the pinion gear and float arm. The electric part of the gauge will not release LP gas by unscrewing the two screws holding it in place. If the mechanical gauge is frozen, the tank must be emptied to remove and replace or free up the float arm, pinion gears, etc.

cimplexsound · 08-25-2015, 09:55 PM

Ok I see. Yes the magnetic type of setup. In this case it might be a good idea to test the magnet. This makes sense. The magnetic sensor is mounted ti a metal mounting plate on the outside of the tank. But again with the RV this old it is highly common for the float arm to freeze and corrode with age. Because of chemical compounds in LP gas that cause it to sometimes freeze when it comes in contact with air. However the pinion and gears can lubricatad with gas treated lubricant and your LP gauge should work again just fine. No problem.

Ryan7361 · 08-27-2015, 08:30 AM

Thank goodness for simple solutions-I cleaned the electric sensor contacts and magnet with contact cleaner and a soft steel brush.
The gauge in the dash now reads perfectly!
Thanks to all for good information!

dduerden · 08-27-2015, 11:12 AM

Ryan-

Glad to hear your problem had the simplest solution, which usually turns out to be the case. That would also have been my first suggestion.

I just want to make a few comments as some of the earlier posts were a little confusing, at least to me. I worked for a propane company for many years so I have a lot of experience with these gauges. The mechanical float assembly inside the tank is pretty durable and generally do not fail except in rare cases. The inside of a propane tank is sealed and an entirely non-corrosive environment, but once in a great while a tooth on the little gear could potentially break, or the entire assembly could break off the inside and fall into the tank. But I don't think we ever saw that in RV service which is generally pretty gentle as compared to something like forklift or industrial service where we normally saw that kind of mechanical failure. There is no "standard" gauge for tanks like that, if it needs replaced it needs to be removed and measured for length of the arm, float and angle and custom ordered, although a propane dealer may be able to determine that from the diameter of the tank and angle/location of the gauge in the tank. Or on a newer unit the rv manufacturer probably knows the part number of the tank they use and the corresponding gauge assembly, but on older units highly unlikely, there are hundreds of different sizes and shapes of tanks and they all need a different gauge.

The "remote sender" is the little dial that comes off with two screws, and that can be safely removed with propane in the tank. As mentioned by other posters the ohm rate varies depending on the gauge, but all aftermarket gauges (as opposed to an oem in dash fuel gauge in auto/truck applications) use the 0-90 ohm sender. You can test it with an ohm meter, take it off the tank and use a small magnet on the back of the sender to move the needle through it's range and read the output on your meter. Again, those rarely fail except for physical damage or corrosion. Any decent propane dealer should have one on the shelf and be cheaper than an rv dealer. You can also replace it with a standard dial with no sender and read it directly on the propane tank if you want.

The most important thing is to only remove the two small screws for the dial, the four larger screws remove the entire assembly and would release all the propane unless the tank is drained first which is of course very dangerous. My suggestion would be to have that handled by a propane professional if needed, being certain 100% of the gas is out of the tank is not as simple as just opening the valve. Also from my experience, on an older tank normally one or more of the screws will be frozen and/or break off when you try to remove them. It is absolutely unsafe to reinstall the gauge without all four screws in place, so the only option is drill out the old screw and use a helicoil or larger screw. Again, your propane dealer has a drill guide fixture designed for this, and since the only way to be safe using power tools right by a tank opening like that would be to nitrogen purge the tank, I would again suggest taking it to a propane dealer if you need the gauge assembly replaced.