[berrygoat]

Originally Posted by Ben M.

I concur with this. I've got a sending unit from NAPA that reads 210. The mechanical gauge read 185 in the same spot. It's annoying, but not enough to change it just yet. Who do you recommend for a gauge sender these days? Obviously OEM GM is preferred but that's not an option here now unfortunately.

As to the problem at hand, have you taken any measurements at all on the sending unit? Put it in boiling water or back in the car and measure the resistance from the button to chassis ground. The values given previously in the thread are what you should be looking for.

I hope I did this right. I set my multi-meter on 2K OHMS, black lead went to negative on battery and red lead to tip of sending unit. I get 1.449. I also touched the black lead to the body of the sender and came same number so ground is good. Im going to start it up, let it get hot and take another measurment.

[Peter Serio]

Originally Posted by Ben M.

I concur with this. I've got a sending unit from NAPA that reads 210. The mechanical gauge read 185 in the same spot. It's annoying, but not enough to change it just yet. Who do you recommend for a gauge sender these days? Obviously OEM GM is preferred but that's not an option here now unfortunately.

As to the problem at hand, have you taken any measurements at all on the sending unit? Put it in boiling water or back in the car and measure the resistance from the button to chassis ground. The values given previously in the thread are what you should be looking for.

The problem with trying to measure ohms on a "live" sending unit is that the resistance value is affected by current flow. So measuring simply from the top button to ground using an ohmmeter with the green wire unplugged is not a valid test.

I am going to test a few temperature senders this afternoon for a customer of mine who bought a set of '66 GTO rally gauges from me. I will try and post a few photos tomorrow afternoon of my benchtop test-setup.

[Old Goat 67]

No, put your meter on the X1 scale and look for a short on the two leads touching which should give you 0 ohms or there abouts. This proves your meter good so you can make measurements.
Then black lead on engine ground and and red lead on sender top (with no wire connected) should give you about 200+ ohms cold, about 95 ohms warmed up and 45 ohms really hot.

That would indicate a sender that is ball park for being correct.

Substituting a fixed resister of 95 and 45 ohms in place of the sender, like Peter & I told you, should give you a mid scale and full scale reading on the gauge, but you'll have to procure those first to do a test like that.

Charles

[Old Goat 67]

Originally Posted by Ben M.

Who do you recommend for a gauge sender these days?

Lectric Limited is the one that Peter recommends and I can vouch that it does give you the correct readings, which you can verify with an IR gun.

Call them to get the right one chosen, start here and go to the sender page.
http://www.lectriclimited.com/mainpage.htm

[berrygoat]

Im going to throw in one of those 9 dollar NAPA senders tomorrow and see if the guage moves off 100. Wish me luck !!!!

[Old Goat 67]

I'm gonna put 50 Cents on the only thing you'll prove is that you wasted $9.

What's your Paypal address? At least that will bring in down to $8.50.

Whay not a 50 cents 100 ohm resistor from Radio Shack?

[berrygoat]

Originally Posted by Old Goat 67

I'm gonna put 50 Cents on the only thing you'll prove is that you wasted $9.

What's your Paypal address? At least that will bring in down to $8.50.

Whay not a 50 cents 100 ohm resistor from Radio Shack?

Is this what I need ?

http://www.radioshack.com/product/in...ductId=2062315

[Old Goat 67]

Yeah, see if they have it in a 1 watt size. Maybe even 2 watt.

[berrygoat]

Originally Posted by Old Goat 67

Yeah, see if they have it in a 1 watt size. Maybe even 2 watt.

Didn't see 2Watt, how's this ?

http://www.radioshack.com/product/in...ductId=2062295

What exactly do I do with it when I get it ?

[berrygoat]

Originally Posted by Old Goat 67

No, put your meter on the X1 scale and look for a short on the two leads touching which should give you 0 ohms or there abouts. This proves your meter good so you can make measurements.
Then black lead on engine ground and and red lead on sender top (with no wire connected) should give you about 200+ ohms cold, about 95 ohms warmed up and 45 ohms really hot.

That would indicate a sender that is ball park for being correct.

Substituting a fixed resister of 95 and 45 ohms in place of the sender, like Peter & I told you, should give you a mid scale and full scale reading on the gauge, but you'll have to procure those first to do a test like that.

Charles

Here is my meter. I don't know what setting to use

[Old Goat 67]

You put the resistor between the green lead on the sender to ground. Sender disconnected. Your gauge should read half way mark.

[berrygoat]

I did it. Went to Radioshack, put the 1W 100 ohm resistor in, turned the key and the needle went to the first mark between 100 and 220. Now what ?

Thank You guys for all the help with this issue.

[Old Goat 67]

Picture?

Is that not half scale?

How about getting a 50 ohm resistor to see if it goes to full scale?

[berrygoat]

Originally Posted by Old Goat 67

Picture?

Is that not half scale?

How about getting a 50 ohm resistor to see if it goes to full scale?

I found this pic on the net. Like I said, lined up almost exactly with the mark between 100 and 220. I'll go back to Radioshack today for another resistor. In my service manual I founf the following:
100 deg 350 OHMS
220 68
260 46.
Im guessing the 100 ohm resistor puts me at bout 165 since its between 100 and 220 ???

[Peter Serio]

Your temperate gauge is most likely lost all of it's silicone buffering fluid. Because the gauges are powered by 12 volts. No buffering left inside of the coil causes the pointer to violently overreact whenever you go to start your car. Turning the key applies 12 volts "+" power to return the pointer back to 100 or cold, from it's last run "normal" temperature. I have seen this problem with both oil pressure and coolant temperature gauges many times. Ultimately no buffering fluid inside of the gauge coil results in one of 2 failure modes: 1 the pointer loosens on the shaft and begins to rotate, throwing the gauge off calibration. Finally, the pointer will simply fall off. Or 2: the shaft begins to loosen in the center of the magnet disc which gives you the same bad result. Your gauge is conjoined with the oil pressure gauge so you'll have to replace the pair.

At the same time I would recommend getting the correct, original AD Delco sender. Find part #AC 213-79., GM # 25037345. When you are dealing with sensitive electrical parts it is ALWAYS best to try and get an original factory sender. The aftermarket manufacturers produce and sell 10s of 1,000s of different parts for a span of perhaps 45 to 50 years+ of cars. They can't possibly be expected to have all of the original data from GM or Ford or AMC
on every single part they make and sell.

As example; that crappy NAPA TS6 sender, for less than $10; what can you expect?

[berrygoat]

Pete, does this look like what I need ?
http://www.ebay.com/itm/GM-AC-DELCO-...item5aea7146f5

[Peter Serio]

Originally Posted by berrygoat

Pete, does this look like what I need ?
http://www.ebay.com/itm/GM-AC-DELCO-...item5aea7146f5

Yes, I would go for that sender.

[GPMESQ]

Originally Posted by berrygoat

Pete, does this look like what I need ?
http://www.ebay.com/itm/GM-AC-DELCO-...item5aea7146f5

If you want the correct single spade connector end on your rally gauge sending unit Lectric Limited has it. The unit above requires replacing the OEM style rubber boot on your new harness.

How did you make out?

[berrygoat]

I'm back !!!! Got a used cluster from a fellow member, installed it and same result...When I ground the lead to the sender it sweeps all the way to the right. I'm on my third sender, this one a GM piece from an earlier post. Thoughts ? It is driving me crazy !!!!!!

[GPMESQ]

Originally Posted by berrygoat

I'm back !!!! Got a used cluster from a fellow member, installed it and same result...When I ground the lead to the sender it sweeps all the way to the right. I'm on my third sender, this one a GM piece from an earlier post. Thoughts ? It is driving me crazy !!!!!!

I am facing the same problem and not feeling any better about solving it after reading this!

You replaced the gauge and are on your 3rd sending unit and same result?!?