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Which 12v temp sending unit for original guage?

Started by 52Cadillac, September 06, 2012, 05:28:20 PM

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52Cadillac

I also have a mechanical under dash unit I wanna throw out, but is it possible to hook both units up with same sending unit? If not how can I employ both at once? If so what would I need? If not possible let me know. also would I need a volt reducer for temp guage?
Thanks, Mike
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LeRoy DeVol

#1
Mike, You should have no problem finding a sending unit at Napa Auto Parts. The answer is "No" you can't run 2 gauges off one sending unit. If you want to run both gauges you will need to find another location for your second sending unit. I have needed a second location for a thermostat to work a electric fan, and the way i did it was to remove the original sender, install a brass nipple with a brass "T" and that gave me 2 places to install my sender and thermostat.

Lee DeVol

52Cadillac

Lee,
So as I understand it 2 senders are used at the end of each tee. I see the need now. Napa told me no go on the sending unit today on a 12v 52, when I called. Which unit should I have asked them for? I should've told em 53. I think first year for 12v.
Thanks, Mike
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LeRoy DeVol

#3
Mike, I believe your car is 6 volts unless it has been converted to 12 volts. I was told that 53 was the first 12 volt Cad. If your car is 12 volts both gauges will probably work with 12 volt sensors. I am not sure about what will work with your original gauge so you may need to buy 1 12 volt sensor and switch back and forth and see what result you get. If it were me i would try to make things work properly with your original gauge and forget the other one.

Lee DeVol

52Cadillac

Yes it was already 12v when I acquired the car. I would prefer to run with just original gauge, but have had some heat issues. They should be worked out over the next week or so. Then I go to the original gauge only.
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kkarrer

I converted my 50 with no problem and 52 is essentially the same.  Just as an aside, there are very cool alternators  available that are housed in an original style GM generator body (powerGen and genernator are two that come to mind). To me, a modern style alternator just didn't look right. I protected the gauge with a resistor, but I think I retained the original sending unit.  I'll have to check.  You should probably look under the dash and see if there's anything attached to the power input side of your temp gauge.  If so, I would guess that you could go with an original 6v sending unit.  If not, it may be that someone replaced the 52 gauge with a 53.  53 was the first year for Cadillac to go to 12v and I think, unlike Ford, they actually used 12v gauges instead of simply having a voltage reducer in-line.  Right now I'm trying to sort this out with my 41 temp gauge which was not only 6v but also positive ground and I still don't have it whipped. 
Ken Karrer 1941 6227D coupe

LeRoy DeVol

Mike, Someone on the forum mentioned that when Cadillac went to 12 volts in 1953 that for several years they used 6 volt gauges with a voltage reducer. It would be hard to find one that you could buy to do the job. I have a 47 Caddy that i converted to 12 volts and the temp. gauge and the fuel gauge both operate best on 6 volts. I Had a hard time finding a resister that would give me 6 volts for these gauges. The problem is that the gauges use very low amps and most resisters that are rated for 12 to 6 volts won't work. Before you spend money make sure that what you buy will do the job. On old cars with original wiring i would recommend using a fuse for the gauges for protection in case of a short .

Lee DeVol   

52Cadillac

Well then how should I handle this one. I have no operating gauges. Speedo, mileage, fuel, temp.
I have a speedo app on my IPhone I used on trip to Texas. We knew how fast we were going.
All should be restored. I've some extras that came with the car, fuel, and temp I believe.. I've no idea which are which. Fuel guage would go to just a hair past 1/4 tank and go to E when low or empty. It stopped working yesterday. A wire was disconnected to it plugged her in, and now stays on past F.
I suspect perhaps the fella before me replaced guages. Ive no way of knowing. Really the under dash wiring needs sorting. Most other stuff works, but it is a mess. I've had a couple shorts already. I have a six volt rebuilt clock to put in, but don't want to screw it up of course. It can be overwhelming. That's the hard part it seems when fixing our cars. No one in the area with the experience to repair or do exactly what you want done. So a lot of us attempt these repairs ourselves. I think I need to back up and think about how to handle the electrical. The voltage reducer for instance I've no idea about which would be suitable. We've all been there buying parts we don't need or can't use. I've not seen any reducers under dash yet.
Yeah Lee I think I read that on here somewhere.
Ken good luck with that positive ground. Tanks for the info on alternator. Mine does looks out of place.
Thanks, Mike
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LeRoy DeVol

Mike, Your problem seems to be more complicated then was first mentioned. Lets start with the basics . Your speedometer could be as simple as a broken cable. Disconnect the cable and check if any resistance to the trans. On my Cad. the cable was special and i had to order one from Calif. Next i would look at the wiring and make sure there is no shorts. The next thing i would do is get a wiring diagram for a 1953 cad. and see how the voltage reducer is used and try to find one. I would also get a diagram for your 1952 & compare the difference. The person that converted the car to 12 volts may have disconnected the power feed to the gauges on till he could figure out how to wire them. The oil pressure gauge along with the temp. & Gas gauge probably 
are fed by the same circuit. Before i would go to far i would check if the 3 gauges are wired to the ignition switch.

Lee DeVol 

P W Allen CLC# 20193

Guys, forget about the these "voltage reducers" that you speak of for the guages on a 53. There are none. The guages on a 53 are 12 volt and are marked as such on the back of the guages. If your running 12 volts on your 52, your best bet would be to get 53 gauges and senders for temp and fuel.
Paul
53 Coupe
Twin Turbine

LeRoy DeVol

Allen, The only information i had on a 53 was what someone had posted about GM using 6 volt gauges on 53 & later cars. It could be that cars other then Cadillac used them.

Mike, I would listen to Allen and try to use 53 gauges if you can find them. If you can't find them, it would be cheaper & easier to use a resister like i did to make things work. No body mentioned if the oil pressure gauge was electric or not. I had to spend $115.00 plus shipping just for a fuel tank sending unit. By the time you buy 2 gauges and a temp. sending unit you will be out $250.00. A resister will only cost about $30.00.

Lee DeVol 

kkarrer

Yes.   I mentioned in a post that 53 Cadillac gauges were 12 and that Ford used a voltage resistor/converter which is still available from NAPA or on-line.  The oil pressure gauge is mechanical.  The ammeter will work fine w/out protection, but you may have to reverse the wires to deal with polarity.  Your issues (besides the clock, radio, and heater fan) are the gas and temp gauges.  I protected mine in my 50 and everything worked fine.  A guy in Holland now owns that car and he still loves it and has no problems with it.  I used a Powergen alt/gen (GM body with alternator inside) to hide the conversion and switched to Pertronics ignition.  My plan was to AC the car, but I sold it before I got around to that.
Ken Karrer 1941 6227D coupe

52Cadillac

#12
Ok yesterday 8 hours electrical with lots of staring. Everything was pretty much hooked up. Newer wiring with some of the old stuff coiled up out of way, and a few loose. Removed all under dash guages. Wiring looked awful, and didn't trust guages. All this stuff was already hooked up just not working.
So I found a loose disconnected wire to fuel guage. Repaired, hooked up and on a full tank it reads a little over a 1/4 tank. Its working as it moves down with use and up when filled, but only to 1/4 tank. Keep in mind my tank was replaced prior with an alum replacement tank of 10 gallons.
The temp unit moves when turned on, but barely to first mark, and no further. I picked a sensor up for 53 from napa, and installed her. Any ideas? Right where the main harness enters thru firewall on engine side is a black box about 2 1/2" long, and about 1/2 wide with 3 wires from harness going to it. Would this be a resister? Or circuit breaker of some type. Will try to post up some pics soon. 
Checked speedo cable by disconnecting both ends and when I turn the transmission end it also turns at other end. I'm assuming cable is good.
Ok so everything was buttoned up, we fire her up and I take my kid to his Moms last night. On the way Home my lights flicker, and I stop to refuel, they flicker some more, back her into garage, and let her run about 2 min. She cut off by herself. So this am I try to find the problem. Shell turn over, but won't fire because the fuel pump(aftermarket on frame won't come on) I almost pulled it and decided to check other electrics no lights, dash lights, rear lights front windows, etc. she most likely would drive if I hooked up fuel pump direct. Question, because I couldn't find the problem, is how do I find the problem?
My Gal took me to Starbucks for a break. She could see the frustration in my mug. I'll be back at it soon.
Regards, Mike
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52Cadillac

shes back running again, the ground was removed apparently when i removed the aftermarket under dash gauges and the wire going to the battery.  reinstalled and she cranked right up. i ran it back to the speaker box.
However the temp gauge is inop as before, the back of gauges had no 12v stamp, however it did have this stamp on top. Can anyone make it out? looks like Sept 11, 097?  029.  No Chit. look at pic 1. does that stamp mean the cluster was redone in maybe 97?
if the temp/ fuel gauge were zapped with 12 when they were 6 will that render them useless? Yes Lee the gauges are wired to the ignition, and a hot wire also came off the ignition feeding the under dash gauges i removed. so the whole system has been fed 12v. I will try reducers as i do have 6v clock to install.

The 2nd pic is unknown to me or its purpose. could it be a volt reducer?

Where can one also purchase old style wiring for our cars? will Napa have it? Ive decided to also run my wiring for the rear windows (just completed), and  to the rear top cylinders not purchased yet.
Thanks, Mike
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kkarrer

Picture #2 looks like your horn relay.  It's not a voltage reducer.  Individual braided/colored wire is available on-line.  I've seen a number of ads on e-bay as recently as today, but a more conservative approach (and unfortunately more expensive) is to get a new harness from Narragansett or one of the other suppliers like YNZ.  Any of the good ones will offer full or partial harnesses and some good wiring diagrams and support from guys who know what they're talking about.  A few years ago Otto Skorzeny created a list of about 200 suppliers.  I think you can still reference it via CLC modified or get it from Hemmings.
Ken Karrer 1941 6227D coupe

LeRoy DeVol

Mike, I talked to someone a few months ago at a co. that rebuilds these clocks. They claim that the 6 volt clocks will work with 12 volts but you need to protect them with a 2 amp fuse as they are connected to the light circuit which is fused at a much higher amps. They say that because the coil in the clock is made for 6 volts, that the momentary application of 12 volts to make the clock work is no problem. If you have any doubts, check with the co. that rebuilt your clock.

Lee DeVol   

52Cadillac

Ok, thanks Ken. I believe the wiring harness was replaced at one point. A lot of it looks new. I was thinking of using period correct wiring for my rear all elec windows and top power to both sides.
I found Ottos vendor list. It's pretty extensive.
A buddy trying to be helpful thinks multiple grounds around vehicle should be done? Would this be helpful, or unnecessary? 
The temp guage sensor from the under dash unit was replaced with a 53 sensor, but its a no go. Should I try one from a say a 55 or whatever until temp guage works? It does go to first indicator mark when ignition is turned on, but that's it.
Allen, If guages are fried I may look for replacements. Well see what developes. Maybe send mine off somewhere to have redone.

I'll order a reducer for my clock, and one for the gauges. And a 2 amp in line fuse Thanks for the info Lee, will do.

Speedo cable seems to turn ok when doing it from tranny end ya can see it turn on cluster end. It must be in cluster as it used to have a rackety noise coming from there.

My alternator indicator light used to work until I removed radiator and reinstalled after a boil out. I have a loose condenser wire thats attached to the volt reg, Volt reg is attached on pass side by rad bolts, but where does this wire go? And also a loose wire coming from the fender headlight area. On volt regulator bottom, middle, or top screw? Or to ground? Someone have a pic of that area with the alternator/volt reg/ and inside pass fender with elec connections?
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LeRoy DeVol

#17
Mike, If your temp sending unit is 12 volts it will not work properly with your 6 volt gauge even with the voltage reducer. Replace the sending unit with a proper 6 volt one. If after all this is done , if the gauge doesn't work then you may need to replace it. I am having problems with your statement about the wiring to your alternator. Your car never had a alternator, so you need  to be very careful about how you wire it as it is completely different from a generator. 

Lee DeVol 

52Cadillac

Thanks, Lee. I'll hold off on Alt. for now. I'll Get the reducers and try a six volt sender. Thx, Mike
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52Cadillac

#19
Reducers picked out. Thx Lee.
6vSending unit is avail from KMLifestyle, but seems a bit long mailing in a money order, etc. Does anyone know of another supplier for the temp sending unit for a 52 that will accept plastic?

Also if I hook a drill to the tranny end of the speedo cable that should tell me if it's in the cluster or the tranny end. Yea/nay?
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