Temperature gauge sending unit and OHM's

gangstakr · #1 (**permalink**) 06-09-2012, 10:29 AM

I searched all through the electrical forum no clear answer. So now I will ask all of you and see if I can get a good answer.
My cooling system has irritaded the hell out of me for some time. Here's what I have done so far.
Replaced water pump about four years ago, it was leaking.
Replaced radiator with a bigger one.
replace temperature gauge with an NOS one that NumberDummy located for me.
Replaced sending unit.
All new hoses and coolant.
Here's the situation, When my temperature gauge starts reading 220 then gets close to 230 (after 230 I think it self destructs) I would pull over and let it cool down before prceeding on my journey. This only happens in So.Cal. rush hour traffic in the summer months.
I met up with the owners of "The Fan-Man" regarding electrical fans being installed. Their fans, when installed properly automatically come on at 195 degrees and cut off at 182 degrees.
My truck was checked and rechecked regarding temperature.
Scary situation watching my gauge climb to 220 then approaching 230. When the needle was on the "2" of 230 my actual temperature was 195 and the fans kicked on at the "0" of 220 the fans shut off.
Ater checking everything out thoroughly, it was determined I'm getting a bad reading on the gauge. (obviously)
So here's the question. How do you know if the sending unit and gauge are compatible? What OHMS should the be reading? If my gauge is reading high how do I get it to read correctly?

NumberDummy · #2 (**permalink**) 06-09-2012, 12:55 PM

Install a Stewart Warner (or similar) direct reading temp gauge and be done with it. FoMoCo gauges were never very accurate, could vary wildly from one like vehicle to another.

The temp needle on my '65 never went past the half way point throughout all the years I owned it (1965/2009)

Besides driving on the worlds longest parking lot on a regular basis, the hated 405 fwy, I drove up to Jawbone Canyon in the Mohave Desert at least once a month to go target shooting. Today, it's reserve for the desert tortoise, no shooting allowed.

gangstakr · #3 (**permalink**) 06-09-2012, 01:17 PM

Quote:

Originally Posted by NumberDummy

Install a Stewart Warner (or similar) direct reading temp gauge and be done with it. FoMoCo gauges were never very accurate, could vary wildly from one like vehicle to another.

The temp needle on my '65 never went past the half way point throughout all the years I owned it (1965/2009)

Besides driving on the worlds longest parking lot on a regular basis, the hated 405 fwy, I drove up to Jawbone Canyon in the Mohave Desert at least once a month to go target shooting. Today, it's reserve for the desert tortoise, no shooting allowed.

Can you find me the correct temp sending unit? I will not put in a stewart warner gauge

NumberDummy · #4 (**permalink**) 06-09-2012, 01:44 PM

Quote:

Originally Posted by gangstakr

Can you find me the correct temp sending unit? I will not put in a stewart warner gauge

We've had this conversation before, a couple of times. Once on the 'Ameche' .. once here on FTE.

I told you that there's an insert that threads into the head, then the sending unit threads into it. Did you replace the insert, or is it still in place? I don't recall what you said.

Why not install a direct reading gauge? You installed the bucket seats you got from that 1968 Ranger, the steering wheel it has, would come in handy in a gang fight.

You cannot drive no more than 2 MPH over speed bumps. The parking lamps are hidden from view...even if you passed out maps to their location, I doubt some peeps could find them, so your truck is faaar from original.

gangstakr · #5 (**permalink**) 06-09-2012, 02:18 PM

It does not matter what my truck is far from, IT'S WHAT I WANT!!!
If your not going to be of any help, step back!! I know what our conversations were about, as you can tell, nothing was resolved. Through trial and error I'll make it work like, I WANT IT TO!
For anyone else out there reading this post,
What is the OHM reading for sending unit? What is the OHM reading for Original gauge?

NumberDummy · #6 (**permalink**) 06-09-2012, 03:37 PM

Quote:

Originally Posted by gangstakr

It does not matter what my truck is far from, IT'S WHAT I WANT!!!
If your not going to be of any help, step back!! I know what our conversations were about, as you can tell, nothing was resolved. Through trial and error I'll make it work like, I WANT IT TO!
For anyone else out there reading this post,
What is the OHM reading for sending unit? What is the OHM reading for Original gauge?

You ragged on me a coupla days ago, didn't bother me a bit, because I'm battle hardened. Now I rag on you and you have a temper tantrum.

I don't know what the ohms are, cuz the parts catalog doesn't say. Do you the truck shop manual? Prolly not, so where else will you get the info?

gangstakr · #7 (**permalink**) 06-09-2012, 04:19 PM

Battled hardened, my ****. You cry like a little girl

when you don't get your way. Your upset about the 68 mustang seats (that were never going to be yours in the first place) You've brought them up in each post I've started. so now you want to take your toys (books) out of the sand box and go home. Well go,

I'll still find my answer I just started here because of the knowledge here.

garbz2 · #8 (**permalink**) 06-09-2012, 05:45 PM

Robert.

Here are the trouble shooting guides form the shop manual.

Loose or Broken Wire from the CV to the Gauge.
Defective Gauge
Defective CV
defective radio Suppression Choke. (What the F this would have to do with it i dunno)

Test Procedure go for the gauge is run to operation and physically check the temperature of the coolant and compare to the gauge.
If the Gauge indicates within the normal section it is working correctly even if it is 20 degrees off.

There are no Ohms reading for the Temp Gauge. It should read 5 volts average while operating.

ohms for cold on the sender is 75.
ohms for full hot is 10.

Garbz

gangstakr · #9 (**permalink**) 06-09-2012, 06:24 PM

Quote:

Originally Posted by garbz2

Robert.

Here are the trouble shooting guides form the shop manual.

Loose or Broken Wire from the CV to the Gauge.
Defective Gauge
Defective CV
defective radio Suppression Choke. (What the F this would have to do with it i dunno)

Test Procedure go for the gauge is run to operation and physically check the temperature of the coolant and compare to the gauge.
If the Gauge indicates within the normal section it is working correctly even if it is 20 degrees off.

There are no Ohms reading for the Temp Gauge. It should read 5 volts average while operating.

ohms for cold on the sender is 75.
ohms for full hot is 10.

Garbz

Thank you Sir. My truck will stay cool now. I do want to get the gauge working as close as possible, but no chrisis.

gangstakr · #10 (**permalink**) 06-09-2012, 06:38 PM

I know it will stay cool now while in rush hour traffic thanks to these two 12" fans.

I just want to get the original gauge working properly. I do know what it's reading when the fans kick on I also know what it's suppose to be reading. Now I just want it all to match. But I'm COOL with it now.

KO1960 · #11 (**permalink**) 06-09-2012, 08:57 PM

What about getting the gauge rebuilt? I saw a recent article on a company called Classic Instruments that will rebuild existing gauges with modern movements. Not cheap, I'll bet. Good luck.

Kurt

gangstakr · #12 (**permalink**) 06-09-2012, 09:51 PM

Quote:

Originally Posted by KO1960

What about getting the gauge rebuilt? I saw a recent article on a company called Classic Instruments that will rebuild existing gauges with modern movements. Not cheap, I'll bet. Good luck.

Kurt

There's no doubt in my mind that the gauge is good. The gauge works and was NOS up until a couple of months ago when I installed it. The sending unit is new but can be the culprit. Depending on OHM's I know I can put a resistor between the sending unit and gauge to bring it down to the temperature when the fan kicks on or when the thermostat opens. But doing this only makes it accurate for the sending unit on the fans. I'm not sure if this will give me accurate readings at any other time. So a proper sending unit for the gauge is my goal.

NumberDummy · #13 (**permalink**) 06-10-2012, 12:08 AM

C1TF-10883-C .. Instrument Cluster Temperature Gauge-Use with Round Speedometer / Obsolete / 29 available NOS

Last MSRP: $69.40 / Dealer net cost: $41.64.

Applications: 1961/66 F100/1100 / 1963/69 N/NT/T500/1000 / 1967/69 F800/1000.
--------------------------------------------------------------------------------
C3TZ-10884-A .. Water Temperature Sending Unit (Motorcraft SW-391) / Obsolete / 384 available NOS

No prices listed on Ford Dealer Parts Locator System.

Applications: All gasoline 1961/64 I-6 & V8 Trucks except Econoline (no V8) & P Series Parcel Delivery / 1965/66 F500/750 w/FT engines / 1965/66 F100/750 240/300 I-6 / And etc.

Some of the above: The sending unit threads into an insert in the cylinder head, there are two different types. One type is pressed into the head, the other type threads into the head.