New member with old gauge problem

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Three Forty Swinger

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Hello,
I'm in the process of repairing my gauges in my 70 dart rallye cluster with a failed/burnt voltage limiter and fuel gauge. I've tested the temp and oil gauges and they both test fine. When this problem occurred the fuel gauge went to empty and the temp and oil went to the max. I was in the process of starting the car after winter storage and don't know how long the gauges were receiving a full 12V but it could have been several minutes before I got back in the car and noticed the problem.
My questions are, how easy is it to track down a NOS Fuel gauge/limiter assemble and would the other 2 gauges assuming they received 12V for several minutes be compromised to the point that they may fail shortly too? Does anyone have experience with the gauge pack and solid state voltage limiter offered through "Charger Specialties"? I have a few local sources to check but I'm probably looking at a used gauge at best. Any info or suggestions would be great, I'm looking at fixing this problem long term with the best possible solution.
My apologies for being long winded. Thanks, Heath
 
Thanks, not a lot of info on the A body rallye cluster, even my original 1970 Dodge Dart manual has no mention or wiring diagram for this dash?
 
The only real difference in the ralleye setup is that the VR is inside the fuel gauge. Other testing methods apply. You don't HAVE to buy a complete gauge just for the VR, unless of course the gauge is fried

This is as good as any:

RTE Limiter Faq - rte

mopar instrument limiter repair - Google Search

However I don't know why one would go clear one way and another gauge the other way, unless you have multiple problems. There's been a LOT of discussion about testing with resistors.........subbing for the sender:

Hey Del, Look what I found!!! An original Miller Gauge tester!!!

Once you get an IVR rigged up, you can easily test all gauges on the bench with substitute resistors, and a 12V power supply or battery
 
Thanks for your reply, yes the fuel gauge is defective also.
I was referring to the fact that removing the cluster is a lot more involved than the non rallye stile with zero mention in the factory manual?
I've tested the other gauges and that is not the issue, they still work fine but have likely seen 12V for several minutes. I was hoping to get info on how resilient these gauges are when subjected to 12V and whether anyone has experience with the reproduction gauges and limiter from Charger specialties or any others? Thanks
 
There are so many conditions/factors that play into what damage occurred. First off, the instrument with the least resistance suffered the most. That is typically the fuel gauge. Since you stated the tank was empty, the oil pressure gauge is second in line ( higher oil pressure = less resistance than low water temp ). In any and every case, inside every thermal instrument, their is a tiny resistor winding on a bi-metal strip. The winding is so small that it creates little to no restriction in movement of the bi-metal strip. The bi-metal strip started out its life arrow straight.
You cant know what condition these components are in until you open each instrument. If the bi-metal strip is found bowed at room temperature, its spent. If the winding insulation is more than slightly discolored ( should be a pale goldish color ) its questionable. Worst case scenario, that winding appears many times its original size with crunchy black coating. Touch it, it breaks away and falls. I've had so many of these come to my hands over the years past. In first look I notice what looks like ground black pepper in the needle movement area. I pretty much know what I'll find inside.
Where so much miss conception exists. General population seems to believe that, "grounded the wire and needle went to full" is adequate test. Zero resistance can move a needle a heck of a lot more than those various "within range" resistances can.
 
Thanks for the insight, yes I agree. The limiter and fuel gauge windings were both burnt and crispy. The gauge smelled burnt before I opened it up. The other two do not smell burnt and I was reluctant to open them up since they are currently working. To make sure I have no choice but to open them up. It looks like I may have a gauge/limiter assemble available to me here locally. Regardless of the condition it sounds like popular opinion is to disable the mechanical limiter and convert to an external solid state unit. I will check my other gauges, replace as needed and convert the limiter and hopefully solve this problem. Any other suggestions feel free. Thanks RedFish!
 
You don't disable the original limiter ! You amputate it entirely.
 
I was able to obtain a NOS fuel gauge locally and feeling very fortunate, I want it to have a long and healthy existence. When you say "amputate" the limiter entirely, I take that to mean that your method differs from what I'm reading from RTE suggesting to just bend the points apart so they no longer make contact. I was looking at ordering their limiter but want to make sure I'm doing the right thing with the internal one? Thanks RedFish!
 
If you do have a NOS gauge, by all means go ahead and install it as is. You don't need any ones aftermarket limiter. The NOS mechinal limiter will work better and can work flawlessly for many years. Neither of us need to argue that "bend the little thingy" bullchit.
THE ONE THING that could help is insight. I can provide that... NEVER TAP ON THE GLASS. Four instruments are placed behind this one lens. A conductive metal matting frame and the lens are held to the bezel with a few plastic "melt stakes". Owners who have 1 or more questionable instrument responses tap on the lens, melt stakes break, major instrument damage occurs. Why ? The ALT' gauge is full unfused 12 volts all the way to its needle. this fuel gauge with limiter inside is supplying a path to ground. A minimal, the needles get bent, loose small bits of paint and likely wrecked in their pivot points. worst is sparks fly. The needle in the fuel gauge turns red and disappears. That tiny aluminum needle doesn't stand a chance with this much current passing through it.
Next is the connector on the oil pressure sender. Most likely that there is no insulator on that wire terminal. If it should get shorted to ground ( happens far too often, especially where distributor wrench comes to visit ) the mechanical limiter would send excess voltage through all the gauges.
As for the TEMP' sender wire getting pinched under a rocker cover or otherwise shorted to alternator wiring,,, this sort of chit happened, just much less often than the for mentioned errors.
Bottom line, you have a new limiter. Do what you can to ensure its happy life in your otherwise old vehicle.
 
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Thanks for your insight! I won't be tapping on the glass! I didn't realize that much damage can occur but never saw the point? I'll hopefully be able to start putting it back together later this week.
 
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