Hi All,
I've been rewiring a '53 Ford F100 (6 Volt, Generator), and am having trouble with the Oil and Fuel Gauges running high. I posted awhile back and got some suggestions - but haven't figured it out yet. I have a little more information now, so am hoping someone out there can shed some light on this for me... I have already replaced the sending units and wiring - ok there. I did not buy a harness, but used what I thought was proper gauge wire - and larger if in doubt.
I have found that the voltage coming from the back of the ignition switch with the truck off and switch to "on" is 6.5 volts, but with the truck running, it's 7.5 volts.
I am wondering what voltage the gauges were originally meant to work on. I found a reference in an old Chilton manual that mentions "5 volts" - but it's not mentioned in the '53 Ford Shop Manual. Also not mentioned in the shop manual - or in ANY of the parts catalogs I've seen, is a "Voltage Stabilizer" that is shown for later years ('57 and later I think).
The back of my instrument panel does NOT have any kind of resistor or voltage stabilizer. Does anyone know if the ORIGINAL 6 volt trucks had such a thing (?) or if the gauges were meant to run off of 6 volts?
Does anyone know what voltage the later model years "Voltage Stabilizer" drops the voltage to? Is it 6 volts or 5 volts or does it just "half" the expected 12 volts? I was wondering if I could use one of these ... if it would only allow the expected proper voltage through (5 or 6 volts?) or if it would just "half" whatever it got, etc...?
Another piece of information, a friend made a "resistor" to drop the voltage from 6.5 to around 5, and it seems to work until I get past 40 mph - at 45, the oil pressure starts going past the "normal" 50# and at 50 mph it's at nearly 80#. So am wondering if I also have an issue with the Voltage regulator. I have not checked the voltage off the back of the ignition switch at 45-50 mph yet to see if it's still 7.5...
Any thoughts or suggestions?

Thanks!

 

53redford, I did find a description of a gauge voltage regulator but was in a 1957 Ford car. I don't think any were used on the 6 volt systems. The voltage regulator would drop the voltage to 5 volts for the fuel and temp gauges. Oil pressure was just a light for the cars. The voltage regulator was a rather crude device by todays standards. It consisted of a bimetallic arm and a heating coil. The 12volts from the ignition switch would cause the bimetallic arm to make and break contacts causing a pulsating voltage the averaged 5 volts supplied to the guages. This info comes from the 1957 Ford Shop Manual for Ford Car and Thunderbird.

This confirms what Barry said about 6 volt gauges used in 12 volt vehicles by Ford.

 

Just a guess on my part, but are you charging to hard? The voltage from the generator is set by a regulator, some are adjustable. What happens if you turn on your lights and high speed fan? Does that drop your oil pressure?

If you are overcharging your battery you should need to add water often.

 

I dug a little further in the 1948-56 Truck Parts catalog. In the illustrations of the dash panels no gauge voltage regulator is shown. Not for 53 to 56. There is one illustration for 53-55 trucks and a different illustration for 56. I take it from that, the 56 trucks used 12v gauges. Another clue is in the description of the Temp gauge. For 53-55 it has 6 volt in the description and for 56 it has 12 volt.

I don't think the 6 volts is your problem. You might check to see if you are getting a ground on the oil sender wire, that would make it read high. The lower the resistance to ground the higher the gauge will read. You can test this per the shop manual. With the ignition switch on to provide voltage to the gauges and the engine not running, momentarily ground the wire to the oil sender until the max reading is obtained. Be careful to not leave the wire grounded after the max reading is reached or you will damage the the gauge.

You can test the output of the voltage regulator for the generator by running the engine in neutral and compare the voltage at idle to when the engine is reved up. That will tell you if the voltage is changing too much.

 

Thanks guys,
Yes, I had checked the gauge - as you mentioned and it does swing over full when grounded. I also have been looking in the shop manual and parts catalogs and have NEVER seen any kind of "constant voltage regulator" for the instrument panel on anything besides '57s and up. I had read somewhere that Ford had produced a lot (!) of 6 volt gauges and used them for several years after they had converted the vehicles to 12 volts - hence the need for the voltage regulator/stabilizer, but again, none is ever mentioned for the '53. I haven't seen one shown in any schematic either.
The voltage from regular is 7.5 when running, but I'll have to check it with the engine reved up.
It sure seems like to much voltage to me - but I am guessing, as I can't find the "proper voltage" listed anywhere - for certain. As I mentioned, I'd seen a mention of "Fords expecting 5 volts" in a 1960 Chilton book... but if this was true in 1960, was it also true in '53 (and earlier), and if so, there should be SOME kind of voltage reducer or limiter or ceramic disk or even in-line resister somewhere... but again, none is shown anywhere I've seen.
A friend told me he was sure it was the voltage regulator, and then later said that he has a friend with a '49-50(?) F1 and it has some kind of ceramic disk resister.
Well, thanks all for the advice and effort. I'll check the voltage with the engine reved up and let you know. I will also check it with the lights on as ***** B suggested.
It's strange that the gauges start out reading "ok" (about 50# oil, etc) until I get past 40 mph and they they go high - again a friend made a 'voltage reducer' (thinking this was the problem) to drop the 6.5v to just under 5... of course with the truck running, there are 7.5 volts coming into the thing, and maybe the voltage regulator is going nuts when I get over 45mph...
Well, again, thanks. I'll let you know when I have some more info. If anyone runs across a listing showing the correct voltage that the 6v gauges work on, let me know. As Roger mentioned also, I was assuming they worked on 6 volts as there was no "resister", etc shown...

 

Are you using the original style voltage regulator with mechanical contacts? In the 54/55 truck manual there is a chart that shows how the regulated voltage changes with ambient air temp. It lists 3 regulators, standard, heavy-duty and Bosch heavy-duty. The voltage values in the chart range from 8.2 @ 35 deg to 6.7 @ 145 deg for the standard reg. A solid state voltage regulator would be more stable.

 

Hi Roger,
I'm not sure how to answer your question - I don't know much about Voltage Regulators. I think it's the original style with mechanical (points) contacts in it.
Looking at it, there is no brand name or logo to identify it. There are 2 numbers on it, and doing a Google search, I haven't come up with anything yet.
There is a number in very small print on the label itself SL 139G1 and another number stamped on the unpainted part of the base of the unit 7141 6V. The cover is blue. That's about as much info as I can give you on it.
I just got in tonight, so haven't had a chance to work on the truck, but will tomorrow and let you know about the voltage we discussed in the earlier post. By the way, as far as the 'ambient temperature", I live in Florida, but the truck is kept in a garage and not usually driven in the rain (after setting outside for 2 years!). Anyway, it's warm and muggy here this time of year.
Thanks again, I'll try to catch up with you later this weekend...

 

I don't know if this helps, but my old 55 F100 had a 12 volt system with the original gages (6 volt) and never had a problem with any of the gages.

The horns were pretty loud, though.

 

On the 53-55 trucks with gauges, there were two or three circuit breakers attached to the driver side rear of the gauge panel. The original voltage regulator should have adjustable points inside it. The contacts in the regulator should open at apporx. 6 volts. Ambient air temperature also has factors for voltage settings and readings. (I am currently looking through the shop manual). At 75* F, the voltage setting in volts is 7.4-7.8 for a standard regulator, 7.2-7.6 for Ford built HD regulator, and 7.1-7.6 for Bosch built HD regulator. Some more specs... The cut in voltage for the regulator is 6.0-6.6 volts. The regulation voltage (or amount regulated) is 7.4-7.8 if your system is showing a voltage level of 7.4-7.8 volts anywhere through the charge system, then there shouldn't be any problems. If it's higher than this, then you need to replace or adjust the voltage regulator, and adjust it to the specifed parameters. If you're lower than this, then you have a bad charging system, and need to test and rapair as necessary.

 

Hi Guys,
OK. First of all, thanks for all the response, and ideas! I rigged up a meter and test cable and took the truck out and ran through the tests and suggestions today and this afternoon hope the results will shed some light on things.
One thing that I think I failed to mention, is that the truck is Negative ground (not Positive ground, as was original) - it was that way when I got it, and I have kept it that way. I was told that the gauges should work either way, and they seemed to in the past. I thought I should mention it in case you thought it could be a possible problem with the voltage regulator/electrical system. It has never seemed to be a problem in the past, and the voltage regulator was replaced (and polarized). I didn't do it, a friend was helping me, and I don't know if he used a jumpter wire or used the field cable itself to touch the battery terminal... It's been 3 years or so. I just assumed he did it correctly. Anyway, just thought I should mention it, just in case!
As far as the road tests today - The voltage with the key on only (truck not started, is 6.5v), running at idle is 7.5 and reved up about the same (7.5-7.7), but at 50 mph, the voltage climbs to 8.2. As WillyB suggested, I turned on the lights, and the voltage (coming out the ignition switch) dropped to 6.6, and the oil pressure gauge WENT TO NORMAL(!) - not immediately of course, it took about a minute to fall back down, due to the way it works, but while the lights were on, it was about normal (using the resister my friend made to drop the voltage to 5v).
So I am wondering if there is a problem with the voltage regulator, as it is within the specs that you mentioned Roger (up to 8.2v), but WMJoe, you stated 7.8 on the high side. I am in right 6.5-7.5 range until 45 mph, when it starts climbing, and gets over 8v at 50mph. Apparently the "gadget" my friend made can't take the 8v or something - but that's besides the point - the regulator voltage is much higher.
WMJoe, you mentioned adjusting (or replacing) the voltage regulator if it wasn't within the listed values (in your earlier post) and Roger, you mentioned using a solid state regulator. What's do you both suggest for my situation? Do you think the Voltage Regulator is outputting too much (8.2) - and if so, what do you recommend (it's about 3 years old). Assuming that's the problem, do you think I should try to adjust the points, or replace it with a new regulator, or, replace it with a solid state regulator.
I have looked through Macs, and don't see a Voltage Regulator for a '53, and looked in National Parts Depot, and they have a replacement listed for the 48-55 6v, but it's the same as what I've got - no "solid state". Do you know if they make one for the 6v (or who makes one)?
One more question - the "gadget" my friend made seems to "kind of work" (to drop the volts to 5), but I am thinking I'd be better off with a "contant voltage regulator" for the instrument panel - but there was no such thing for a '53 - the nearest one is for a '57, and I'm assuming it's for a 12v system. Does anyone know if that (or any other resistor/regulator) will work with the 6 volt system? I think they work just like the bimetal gauges in the dash now, heating up and breaking contact over and over, but I'm wondering if they would "heat up" enough with only 6 volts coming in. A 12v flasher (turn signal) doesn't do anything connected yo 6volts, for example, it never gets hot enough.
Well, I appreciate the time and advice. Let me know what you think about the voltage regulator - if you think its "ok" (at 8.2v) or is spiking and should be adjusted or just replaced, when you have time... Thanks again all.

 

The specs I listed are from the ford truck shop manual. I would be apt to use them rather than anything else, just because they are from the shop manual, and do match the original specs. The gadget sounds like the typical voltage reducer, but they are not recommended for use on gauges. Why it spikes over a certain RPM, i do not know, but I can check the books again. If it is converted from positive ground, then all the gauges would read backwards, unlee the entire system was changed to meet the current flow of the negative ground. The manual does state that you should NEVER polarize using any method other than touching the field and battery wires to eachother very momentarilly. Other methods will cause excessive voltage flow through the system, and will lead to a grounding of the contacts inside the generator, and or regulator, which will lead to premature part failure.

 

OK,
So you think the regulator is bad, and should be replaced? or adjusted? It seems strange it works ok until 50 mph and then surges. I was trying to figure out how the regulator works, and am not sure if it sounds like the center winding (current regulator) is at fault, or the Voltage regulator coil is the problem (or both).
Not sure now he polarized the unit - but it seemed that he used a jumper wire, which, as you stated is NOT recommended. So maybe it's best to start over with a new unit. Perhaps the unit was damaged (or weakened) and this is related to it not operating properly at higher rpms (just guessing).
What do you recommend on the Voltage Regulator (adjust or replace, and with original or solid state, as mentioned by Roger - although I haven't found one yet). I mentioned without the voltage reducer (gadget), the gauges read full (oil past 80#) - not grounded, just reading high(!), so if I replace the Voltage regulator, I will still need the gadget, or a replacement for it. I am really frustrated with this "issue" as I have NEVER seen any mention of any kind of instrument panel "constant voltage regulator" or reducer, etc for the '53 (or 6 volt trucks) - and I assumed the gauges worked off 6v... but obviously, this is not correct, as they register too high. Do you know if a later model voltage regulator (for the instrument cluster), from a '57, for example, would drop the voltage to the correct amount? Looks like you have a '53 - still 6V? do YOU have any kind of reducer/regulator in your truck for the gauges (that you know of)? Let me know what you recommend on the Voltage Regulator also, when you have time. Thanks for the information and time. By the way - awesome Fire Truck!!!

 

OK, the reason the voltage climbs with the speed of the truck is because you are spinning the generator faster, and it is making more voltage. That is just the way generators work.

The regulator is supposed to limit that by decreasing the field current as the voltage increases. When the voltage is low it gives you more field current, when voltage is high it gives you less.

You have a 6 volt lead acid battery, which is 3 cells. When fully charged each cell should be 2.3 volts - 3 of them should read 6.9 volts. Therefore I expect a 7.2 volt charge should be all you want - any more than that will overcharge your battery.

It does not seem reasonable to me that someone would make a solid state regulator - when they became available we had been running alternators for several years, and 12 systems even longer. I don't think you will ever find a 6 volt solid state regulator.

That being said, I do think you need to adjust or replace your regulator. It is possible that your regulator is not working at all and 8+ volts is all your generator will put out, or maybe just cleaning the contacts and adjusting will repair it.

Anybody who knows electronics could build you a circuit to provide a constant voltage to your dash, but that would not fix the root problem.

It has been years since I worked on DC circuits, and even longer since I worked with generators. It is possible I have mis-named some components, and my voltage may be off a bit, but, in general, I am sure I am correct in thinking your problem starts with the regulator. I wish I could be more help -

My suggestion is that you PM our Moderator, Earl, who has rebuilt the electrical system in his truck and seems very knowledgeable on this subject

 

The 53 is all 6 volts. I would just replace the regulator to start with. It may or may not be the problem. 57 is 12 volts, and things won't work right, if at all. As to a reducer for my trucks, no mine are all converted to 12 volts, it's less costly when something fails. My dads 55 has it's original 6 volt parts, but has been converted to 12 volts using a voltage reducer. You won't need one for yours because it's still a 6 volt system. The problem is a voltage spike, that would make me suspect the regulator. Why it affects the fuel and oil gauges, instead of the volt gauge, is strange. It should mess with the volt meter only, unless they have been intertwined some where, which they shouldn't be. There should only be one wire coming from the charging system into the rest of the trucks wiring. It should be the 10 ga yellow batt wire off the regulator. It should go through the harness straight through the loop on the back of the gauge, and attach at the headlight switch. It joins another 10 ga yellow wire that runs to the battery cable side of the starter solenoid. This is the only path the charging system takes, and it should not be intercepted or redirected anywhere else in the harness. The other gauges are only connected to the battery gauge through there ground, whichis physically through the attachment at the dash of the speedo cluster, and electrically through the wire that goes to their sending units. They should never come in contact with any other part of the system. They are powered by a single 14 ga yellow wire from the ignition switch, it runs from the GA terminal on the back of the switch, and goes to the top right gauge, then to the top left gauge. The bottom right gauge should be connected by a short 14 ga yellow wire, or jumper wire at the top right gauge. Make sure this is how it's set up. Verify where the wires are coming from and going to, to rule out any cross wiring. Then, check your output at the batt side of the regulator. You should be at roughly 6 volts with the truck off, this is the battery's power you're reading. Witht he truck running, and at around 1500 RPM, you should be reading in the 7.2-7.6 range. If you go much higher, then you're spiking. If you're spiking, it could be a problem in the regulator itself.

 

OK, thanks WillyB - I think you're right on the mark... very helpful - thanks for the info. I think I need to replace the Voltage Regulator and properly polarize it (for sure) and see where I am from there. Thanks for the info on the battery and regulator (explanation) - you might be right - that the regulator is not working at all...
I'll see if I can get ahold of Earl as you suggested...