[317th FMS]

Just thought I would pass on some info that might prevent a headache for someone else. The replacement water temp senders are not correct for the early Birds (GM Borg Warner etc.) they have the wrong resistance values. They give a 20 degree higher reading making you think you have a overheating problem. I temporarily installed a mechanical gauge and got 190 which is OK. Then replaced sender 3 times. Then the gauge. Then the printed circuit on back of cluster. Giving up I sent gauge and sender to get calibrated and they told me what was going on with the sender. I have seen a few correct ones on Ebay. They have the AC Delco script on them. Maybe someone else can chime in with there experiece on this.

[2manyT/A'S]

Good INFO!

Thanks for sharing.

[RicksGTO]

Good post as this is not something you want a false reading on for sure. Lectric Limited has correctly calibrated sending units as well. I have been told by several people about them and have one but the car is not running yet so I can't give feedback on their accuracy first hand yet:
http://www.lectriclimited.com/mainpage.htm

.

[317th FMS]

25.00 for lectriclimited sender sounds like a bargain compared to what I paid. Wonder how many radiators and water pumps were replaced because of this sender problem.

[CaptCrunch]

THANKS!.........good to know..........

[giles]

I ran into this issue as well. High gauge indicated temp shortly after a fresh rebuild, recore rad, etc. Checked it with an infrared temp reader - 195F! right where it should be. Borrow or buy an infrared temperature checker before you start replacing alot of expensive stuff. Point it right at the thermostat housing to check the real temperature.

[70RAlll]

I had this same problem years ago. Bought one from Electric Limited or H&H..can't recallw ho it was, and it was still wrong.. The difference is "with guage package" cars(TA"s and Formy's) have a different sender. Most repo senders just use the more common dumb light sender which reads wrong. Maybe the repo's are correct now.. But there is no "calibration" with these, they are not adjustable. Either they aremade correctly or not. Look at one, you will see...there is no way to open it up and change things out.. I suggest finding a used one on Ebay or finding a NOS one.. I bought numerous NOS ones for $75 or so.. I think I have 3-4 now, just to make sure I will never go through that again.. Maybe the repo's have changed the resistence, but yea ago they had it wrong.. Just my opinion and experience..Not trying to bash one company over another..

[RicksGTO]

Hey Steve, sorry it wasn't accurate, Lectric has a good reputation and they go out of their way to talk about how they've solved the problem but it sounds Bill was right. I've got one too but as I said I haven't been able to test it yet.

[eaglesan13]

I bought the Lecric one also but have not fired up my engine yet. However, I put the sensor in the intake manifold (72 cast iron intake) rather than in the cylinder head (6X-8). I guess we'll see if this makes a difference.

[Old Goat Racer]

Could this be the right one?

[njsteve]

No, that's the emissions/TCS sending unit that mounts on the passenger side cylinder head. It operates the solenoid that restricts vacuum to the distributor vacuum advance unit at certain temperatures.

[Old Goat Racer]

OK, but it's mounted in the intake manifold on a 70' GTO

[Old Goat Racer]

How 'bout this NOS one

[njsteve]

Yup. Thats the correct one but depending upon the year of manufacture it could be the later "one sender fits all" model.

[njsteve]

On a whim I went to Autozone and bought a Wells brand #TU5, which is the replacement sender with the slide-on terminal. I tested it against the mechanical gauge and the dash gauge. Here are the results when the car was warmed up and driven four miles. (ohm readings made by touching pos lead to terminal end and neg lead to outer casing of sender unit):

TU5: when the engine was cold and the ambient temp was 80 degrees, the factory dash gauge read 0. At this time the ohm reading was 000.548. Once the car was warmed up and driven 4 miles, and a mechanical gauge capillary unit was immersed in the radiator coolant, the mechanical gauge read 160 degrees. At the same time the dash gauge also read 160 degrees. The ohm reading at that time was 135.500.

When the Lectric Limited model 01513321 was at 80 degrees ambient temp and the engine was cold, the dash gauge also read 0 and the ohm reading was 000.549. When the car was warmed up, driven 4 miles, and the mechanical gauge read 160 degrees, the dash gauge read 215 degrees and the ohm reading was 348.000.

As you can see, the $25 Lectric Limited sender that is sold as "correctly calibrated" was nowhere near as accurate at the $6 Autozone TU5 made by Wells.

I have 70RAIII sending me an original used, GM 1513321 next week so I can get the readings off of that one and compare. (I'll most likely end up using that one in the car, just to be truly correct)

[Old Goat Racer]

Originally Posted by njsteve

Yup. Thats the correct one but depending upon the year of manufacture it could be the later "one sender fits all" model.

I've had a few of these for 20+ years. How can one tell when they were made?

[njsteve]

Originally Posted by old goat racer

I've had a few of these for 20+ years. How can one tell when they were made?

I think the good early ones have the part number stamped above the threads versus the newer GM ones that don't have anything there.

[317th FMS]

If you google "1513321 GM" and click on that first PDF file there is alot of good info on this. I tried to add to the thread but it was too big a file.

[70RAlll]

Originally Posted by old goat racer

How 'bout this NOS one

Steve-
this is two of the 3 NOS units I mentioned to you I had. SOPme guy was selling these on Ebay a year of so ago, must have found a bunch of them in an old dealership. I have one additional in an original box.. ANyway, my friend is sending the original nail head model and I will have you the unit by mid this comming week. FWIW>.. this friend of mine found 6 of these temp senders used. He was about to throw them away!! He thought with repo's available no one would want them !!. Iff anyone needs one, PM me and I will help you get one..

[Norwood]

So Steve with all that , you are saying the AutoZone unit read correct?