Temperature Sender

[Steve Shauger]

Steve try the Wells sender I mentioned. They always read at the quarter graduation. To compare original versus new/repop you would need to verify the resistance levels at specific temps. I have both maybe I'll make a stew and check the resistance levels. If I recall correctly they call out the same sending units regardless of placementfor several years 68-72ish. Possibly the difference was in the gauge ( they may have a different voltage divider in the gauage based on placement and application. I only use the factory gauge as a ball park anyway.

[njsteve]

The Lectric Limited sender reads 63.7 ohms when the car's dash gauge says 220 degrees. (Pos lead on terminal end of sender and neg lead to threaded side of terminal, as well as to actual engine ground)

The thermometer, as well as a capillary bulb mechanical gauge immersed in the radiator at that time, both read 190 degrees.

I'll have to wait til she cools down to get additional readings.

[Mr70]

Steve
Are your thermometer & capillary bulb gauge,reading coolant temperature after it's passed through the cooling fins & cooled down some on the passenger side of the radiator?

[njsteve]

The coolant is flowing (thermostat is open) and the car is idling with no airflow over the fins so I don't believe that the cooling effect of the radiator would account for the 30 degree temperature discrepency. I will try mounting the actual mechanical gauge in the same cyl head spot next.

If you all recall, I had this same problem with the SW electric temp sender and gauge in my hemi Charger until I replaced it with a mechanical gauge and finally got an accurate reading.

[njsteve]

Went to Autozone and bought a TU5, which is the replacement sender for 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 someone sending me an original GM 1513321 next week so I can get the readings off of that one and compare.

[mockingbird812]

Nice work &quot;Mac&quot;. Now, can you make your own sender with some string, a paper clip, and a wad of chewing gum? [img]<<GRAEMLIN_URL>>/dunno.gif[/img] [img]<<GRAEMLIN_URL>>/beers.gif[/img]

[L78racer]

found this info online.
http://www.lbfun.com/warehouse/tech_info...geCF-Thread.pdf

[njsteve]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Ls6racer</div><div class="ubbcode-body">found this info online.
http://www.lbfun.com/warehouse/tech_info...geCF-Thread.pdf </div></div>

Wow! Those guys make me look like like an amatuer. (Hey wait aminute, I am) [img]<<GRAEMLIN_URL>>/grin.gif[/img]

One thing I notice is that their chart readings go the opposite way mine do ohm-wise - their resistance drops as temp rises. I'll recheck and see if I'm reading my gauge wrong - or just putting decimal points in wrong places.

[njsteve]

OK, I kicked the wife out of the kitchen and did a little experimentation on the stove with a pot of water, a candy thermometer and a digital ohmmeter. Here are the results:

80 degrees: Wells at 650 ohms, LL at 573 ohms
90 degrees: Wells at 526 ohms, LL at 445 ohms
100 degrees: Wells at 429 ohms, LL at 365 ohms
110 degrees: Wells at 328 ohms, LL at 266 ohms
120 degrees: Wells at 283 ohms, LL at 227 ohms
130 degrees: Wells at 250 ohms, LL at 200 ohms
140 degrees: Wells at 216 ohms, LL at 170 ohms
150 degrees: Wells at 198 ohms, LL at 155 ohms
160 degrees: Wells at 173 ohms, LL at 133 ohms
170 degrees: Wells at 157 ohms, LL at 119 ohms
180 degrees: Wells at 135 ohms, LL at 101 ohms
190 degrees: Wells at 120 ohms, LL at 89 ohms
200 degrees: Wells at 109 ohms, LL at 79 ohms
212 degrees: Wells at 104 ohms, LL at 75 ohms

And as a result of my weekend TempSender-Palooza, I am going with the Wells sender as the one that makes my temp gauge far more accurate when it comes to reading what the coolant temperature actually is, as corroborated by an actual thermometer as well as a mechanical temp gauge. (That is, until the original GM unit arrives)

I will update with the original GM sender when I get that. The original ones have the part number stamped above the threads. The later GM ones have no part numbers whatsoever and seem to be a generic replacement.

[njsteve]

Just took the car out for a test drive. I hooked up the mechanical gauge in the sender location. It's about 97 degrees outside at the moment and the car ran around 190 degrees most of the trip with the A/C on full blast.

Once you sit and idle for an extended period or shut the car down, the temp really spikes (230) but I think that is due more to the sender location on Pontiacs that is right between the two exhaust port tunnels on the HO cylinder heads. So actually, the heat soak from the exhaust manifolds may play a major part in some of the high readings when there is no airflow. The heat soak may be heating the outside of the temp sender more than the coolant is heating the sender bulb inside the cyl head.