'67 Temperature gauge problem...

[Patrick T.]

I just bought an AC Delco '66-'67 temp gauge. It's a GM Restoration part #6402594. Inside there is a note saying that "this gauge is precision wound to original Delco specs and is extremely accurate. If your new gauge does not read correctly, then you may have to replace the engine sender unit with the correct delco part. Your Dealer who sells these gauge has the correct part in stock".

So I had one of those repro sending units that was correctly calibrated for my original gauge and it worked like a charm. However I installed the new gauge and it reads too low, barely over 100 degrees where it should read 180. So I go to Napa Auto parts store and buy the plain jane sender for a '67 SB. Same thing, it reads to low.

So I go back to the Vendor who sold me the gauge and bought the AC Delco sender without the external resistor part #AC1513321 and it reads too low. So three sender's tried and the gauge still won't read correctly. If the gauge is calibrated to original GM specs, ONE of the sender's should have worked. Does anyone know of a sender and part # that will make this read 180*? Thanks PT

[Wayne W.]

Re: '67 Temperature gauge problem...

They have probably tried to calibrate the repro gauge to read correctly with the modern, fits all, sender. Typically originals will read high with the new sender. What does it do when you ground the wire?

[Patrick T.]

Re: '67 Temperature gauge problem...

They have probably tried to calibrate the repro gauge to read correctly with the modern, fits all, sender. Typically originals will read high with the new sender. What does it do when you ground the wire?

Wayne, which wire are you talking about? The gauge does work, but is reads way too low. This is such a PITA, I don't see why GM Restoration Parts doesn't sell the new gauge and include the correct sender which has been pretested. I guess that would be too easy! PT

[Joe R.]

Re: '67 Temperature gauge problem...

Patrick,

Wayne is asking: When you ground the green wire going to the sending unit in the manifold to the engine or other suitable ground does the gauge in the car go all the way to the right?????

JR

[Patrick T.]

Re: '67 Temperature gauge problem...

Patrick,

Wayne is asking: When you ground the green wire going to the sending unit in the manifold to the engine or other suitable ground does the gauge in the car go all the way to the right?????

JR

Thanks JR, I'll do that. BTW, your sending unit worked right on the money WITH the old sending unit. PT

[Patrick T.]

Re: '67 Temperature gauge problem...

Patrick,

Wayne is asking: When you ground the green wire going to the sending unit in the manifold to the engine or other suitable ground does the gauge in the car go all the way to the right?????

JR

OK, JR, I ran a jumper line from the sending wire on the manifold and grounded it. Then I turned the key to "start" and the gauge pointer peggs out all the way to the right. I disconnected the jumper and the pointer went back to 0. So, what is this telling me? Thanks, PT

[Wayne W.]

Re: '67 Temperature gauge problem...

OK, JR, I ran a jumper line from the sending wire on the manifold and grounded it. Then I turned the key to "start" and the gauge pointer peggs out all the way to the right. I disconnected the jumper and the pointer went back to 0. So, what is this telling me? Thanks, PT

Well, It tells us that the gauge is capable of getting up into those high ranges with zero resistance. The sender obviously doesnt go low enough to get there. I would drop the sender in boiling water and check the resistance. Then compare that reading with the resistance chart, just to see how it compares. My opinion is, you have a defective gauge.

[Patrick T.]

Re: '67 Temperature gauge problem...

Well, It tells us that the gauge is capable of getting up into those high ranges with zero resistance. The sender obviously doesnt go low enough to get there. I would drop the sender in boiling water and check the resistance. Then compare that reading with the resistance chart, just to see how it compares. My opinion is, you have a defective gauge.

Well I guess in that case I'm screwed because the gauge is non-returnable. Another fine GM product.

[Joe R.]

Re: '67 Temperature gauge problem...

Patrick,

By chance have you used teflon tape to screw the sending unit into the intake manifold?

JR

[Patrick T.]

Re: '67 Temperature gauge problem...

Patrick,

By chance have you used teflon tape to screw the sending unit into the intake manifold?

JR

Jr, no teflon tape ever. Why is it that on my old gauge, your sending unit worked perfect and now on this new guage it reads low, can't figure that one out. PT

[Gerard F.]

Re: '67 Temperature gauge problem...

PT,

Went through the same thing with a new temp gauge on my 67 a couple of years ago. Same warning on a repro from CC. Went through 4 sender units, with a meat thermometer taped to my radiator inlet hose for about a year to check.

Final one worked and I think it was the one from Lectric Limited, but after I did a good cleaning (and a little bending) of the connector to the sender.

[Chuck G.]

Re: '67 Temperature gauge problem...

Patrick:

Perhaps Rick Stotler of Rick's Restorations could help you out. Rick's up my way now, about 8 miles from me in Joppa, MD.

Maybe Rick could re-calibrate the gauge itself. I'm sure he's run into this problem before. IF it's a GM Restoration Parts gauge, one would assume that the gauge was made correctly.

I'm aware that many have problems with finding a proper sender. Another thought, maybe Rick could re-build your original gauge, and you could use JR's sender. You know that that combo works.

Give me a call.

Chuck

[Joe R.]

Re: '67 Temperature gauge problem...

Patrick,

It seems strange to me that your original gauge worked with the sending unit and you would go and buy a new GM reproduction gauge. OK, if the old one isn't pretty, at least it works.

There are two companies making GM reproduction gauges. One, and I won't mention the name (FARGO) that doesn't work as well or as often as the other (KB).

Either take your old gauge and have it silkscreened to new cause it works and throw the GM repo away. Ask CC to replace the gauge or purchase another one that works.

Taking a flakey gauge and calibrating it to a sending unit will only take you down this road again when it fails the second time.

My two cents,

JR

[Ken A.]

Re: '67 Temperature gauge problem...

I just bought an AC Delco '66-'67 temp gauge. It's a GM Restoration part #6402594. Inside there is a note saying that "this gauge is precision wound to original Delco specs and is extremely accurate. If your new gauge does not read correctly, then you may have to replace the engine sender unit with the correct delco part. Your Dealer who sells these gauge has the correct part in stock".

So I had one of those repro sending units that was correctly calibrated for my original gauge and it worked like a charm. However I installed the new gauge and it reads too low, barely over 100 degrees where it should read 180. So I go to Napa Auto parts store and buy the plain jane sender for a '67 SB. Same thing, it reads to low.

So I go back to the Vendor who sold me the gauge and bought the AC Delco sender without the external resistor part #AC1513321 and it reads too low. So three sender's tried and the gauge still won't read correctly. If the gauge is calibrated to original GM specs, ONE of the sender's should have worked. Does anyone know of a sender and part # that will make this read 180*? Thanks PT

Two things to ask/check:
Did you reuse your old ceramic resistor on your new gauge? If so, it will read low. Second, could someone have wired a resistor in your green wire to get an old sending unit to work? Check with an ohmeter-there should be no resistance between the terminal clip & the gauge.

[Joe R.]

Re: '67 Temperature gauge problem...

Patrick,

After you removed the ceramic resistor on the back of the new gauge as per Ken Anderson's instructions, did the new GM reproduction gauge work correctly?

I think you will find a white paper in the original box that instructs the installer NOT to use the resistor from the original on the NEW gauge.
Maybe the seller of the gauge removed the instructions.

Regards,

JR