C1 Reproduction Temperature Senders

[Richard M.]

Re: C1 Reproduction Temperature Senders

Update:

I received 2 K&B Senders from Zip last night. See tests below.

I verified the dash gauge using a potentiometer set to apx 105 ohms. Ken eluded in a previous post that 180*F is 105 ohms. The gauge meter on this car is off a bit but I will consider it good. By no means is it high by 20 to 30 degrees F as seen with the previous senders.


My bench test to test the senders is a bit crude and I also got a variance between my IR gun and KD-409 thermometer, so accuracy may not be exact. It is hard to get a confident reading in clear water using the IR gun, so I opted to use the thermometer placed next as close as possible to the sensor base. Again, I probably have a variance with this setup, but I wanted to do some basic measurements before draining this radiator for the 6th time now. Maybe more than that due to the water pump from he!! issue discussed elsewhere.

Here is my test setup. I will use my propane torch at low setting to heat up the stainless cup and record the resistance data as the temperature rises. I marked each sender KB1 and KB2.

I tested both senders at ambient air, apx 77*. I expected a variance between the two of them, albeit a little more than I expected. Maybe this is normal.


More to come after testing at heated temperatures from 120* to 200*.

Rich

[Richard M.]

Re: C1 Reproduction Temperature Senders

Update:

It only took 10 sending units to get one that worked in this 1961 Corvette.


For the record this was a very frustrating experience that I spent a enormous amount of time on, with continued disappointing results using sending units from at least 5 different suppliers.

It appears that many of the manufacturers of this part do not have a valid test of the assembled units, because if they did, we all would not have such difficulties with such a simplistic automotive electrical assembly. In my opinion, each and every sending unit should be tested in such a way that it is heated in a similar final usage environment using basic test equipment to verify range of operation over at least 3 temperature data points. Ambient, normalized, and Over-temperature. Since most C1 and C2 Corvettes were supplied with 180 degree thermostats, the test specifications should have most accuracy at or near this temperature.

This is not a complex auto part, yet it appears that the manufacturers have no idea how to test it. It has been discovered that typically, just the internal thermistor is tested, to what spec and resistor range and at what temperature I have no knowledge, and that the assembled unit is NOT tested. This to me is the major hole in the manufacturing process and quite simply why the entire community has this problem. It's a guessing game for the suppliers, well most of them it seems. Allegedly there are some that work, and in my opinion, it's just plain luck. They are relying on a test of the internal part and not the entire assembly.

For now, all I will say is that NAPA is my hero. They are the only supplier that I have seen that actually documents their specification. I did a thorough bench test, using the exact same methods as ALL of my other tests, in heated water using multiple measuring tools for accuracy. This is the part and the documented data. For your information, the part is made in Mexico/ It has no markings and will fail in a judged environment. However, it is functional.

ECHTS6469 Attributes
	# Switch Terminals: 1 Temp Sender Switch Temp Rating: 72-88 Ohms Resistance At 220 Deg F Temp Sender Switch Thread Size: 1/2" x 14 Dryseal Temperature Switch Thread Size: 1/2" x 14 NPT UNSPSC: 26101700

After spending many man hours, multiple coolant drains and refills, multiple pre-tests on the bench, discussions with vendors and suppliers, nervousness swapping the parts into and out of a extremely valuable FI inlet manifold, I can finally state that I have a part that finally works. It's in the car and works as expected.

Rich

[Joe L.]

Re: C1 Reproduction Temperature Senders

Rich------


The thing that surprises me is that NAPA has a manufacturing source for this part which is different than the manufacturing source for most of the other aftermarket brands.

[Mark E.]

Re: C1 Reproduction Temperature Senders

Rich,

Thanks for documenting this. I'm glad you have it sorted out.

Teflon tape is shown on the treads of one of the senders. For proper ground, remember to not use tape or thread sealer on these.

[Richard M.]

Re: C1 Reproduction Temperature Senders

Rich,

Thank you for this thread. I learned a lot.

In 2014 I naively replaced the sending unit in my '70 LS-5 with a new one from NAPA. PN TS6469SB; $8.05.

It's a button style unit similar in appearance to your photos. This thread suggests it may be the same application as your car.

Dumb luck maybe, but it SEEMS to work ok. I haven't checked it with an IR gun or other means, but it seems accurate- from cold start, the gauge slowly moves up until it reaches about 160* (thermostat setting), then stays there until/unless it's idling or running hard in hot weather. In those cases, it may creep up and stabilize a bit below or above the 210* mark.

So in this case, the sender seems to perform the same below or above 180*, i.e., no apparent nonlinear readings.

Just another data point suggesting some aftermarket senders may be ok.

Mark, That was a great lead. Napa nailed it !

Rich,

Thanks for documenting this. I'm glad you have it sorted out.

Teflon tape is shown on the treads of one of the senders. For proper ground, remember to not use tape or thread sealer on these.

The first thing I did before installing was to remove the Teflon tape. I left it on in case the bench test failed so I could return it in the same condition.

BTW, there is a number "45" stamped on the bottom of the unit if that becomes a telltale in the future.

Rich------


The thing that surprises me is that NAPA has a manufacturing source for this part which is different than the manufacturing source for most of the other aftermarket brands.

Joe, I agree.

[Dan B.]

Re: C1 Reproduction Temperature Senders

Rich,

Very interesting that your researched revealed no valid method to test for the "assembled part" exists at the manufacturing end. I think you finally hit on the area that has plagued this part for quite sometime. It would not surprise me if it turned out that there is some subtle variation in the current manufactuing process that is different from GM original and older US made that is screwing up the current finished product. For most of us that have carbureted cars, it's a PITA to have to mess with multiple senders as the water outlet also has to be removed (for clearance) and resealed each time. Additionally, I did some comparisons and the height of the connector button in relation to the base was too high on the newer reproduction and in relatiion to some older senders I compared it to. Nice thorough job! Dan

[Richard M.]

Re: C1 Reproduction Temperature Senders

Rich,

Very interesting that your researched revealed no valid method to test for the "assembled part" exists at the manufacturing end. I think you finally hit on the area that has plagued this part for quite sometime. It would not surprise me if it turned out that there is some subtle variation in the current manufactuing process that is different from GM original and older US made that is screwing up the current finished product. For most of us that have carbureted cars, it's a PITA to have to mess with multiple senders as the water outlet also has to be removed (for clearance) and resealed each time. Additionally, I did some comparisons and the height of the connector button in relation to the base was too high on the newer reproduction and in relatiion to some older senders I compared it to. Nice thorough job! Dan

Dan,

I feel that the NAPA part may have a more valid post-assembly test since they are the ONLY manufacturer which I have seen that actually publishes it's specification. No others publish their spec, at least the ones that I've encountered. Why the big secret is beyond my comprehension.

Unfortunately, some are more concerned with appearance and configuration and have neglected the main objective of functional accuracy.

[Richard M.]

Re: C1 Reproduction Temperature Senders

Final Test Data below. I bought 2 more Napa parts and tested those, one of which is the Pro Former TS6469SB part with no spec shown. It has a 1 year warranty and no Teflon tape. The TS6469 Echlin part has a 3 year warranty and Teflon tape. These factors must determine it is 2x cost over the 'SB' version.

I retested the others. All tests under identical conditions and identical test methods and equipment.

The data speaks for itself. I'm done with these for a while. It was suggested to me that I send the defective K&B units back to my vendor for refund. I will do that. Advanced Auto will get their TU-5 back as well. I'm stuck with the $45 GM NOS part as well as the others that failed.

Rich

[Jim D.]

Re: C1 Reproduction Temperature Senders

Such a simplistic part. You wouldn't think it would be that difficult to reproduce correctly. Great detail, as always, Rich. Will be interesting to see your end result.

It's not, we sell 1000's.

It was suggested to me that I send the defective K&B units back to my vendor for refund. I will do that.
Rich

Thanks for all the research and hard work Rich. I gave up trying to get something more accurate than mine that reads a little low.

Obviously sales volume isn't an indication of a quality product.

[Larry M.]

Re: C1 Reproduction Temperature Senders

Rich:

Has K&B offered any explanation for their two senders not performing according to GM spec?? I just bought one (K&B) based upon what was claimed earlier in this thread. I guess now I need to go and check it's calibration just like you did.

Larry

[Richard M.]

Re: C1 Reproduction Temperature Senders

Rich:

Has K&B offered any explanation for their two senders not performing according to GM spec?? I just bought one (K&B) based upon what was claimed earlier in this thread. I guess now I need to go and check it's calibration just like you did.

Larry

Larry, Yes you could test it, like any other unit to be sure before installation. I got 2 that failed my tests. I put one in the car and it failed there too. I guess I'm just unlucky as others have had no problems.

Rich

[Richard M.]

Re: C1 Reproduction Temperature Senders

Thanks for all the research and hard work Rich. I gave up trying to get something more accurate than mine that reads a little low.

Obviously sales volume isn't an indication of a quality product.

Jim, Ken makes good products and I will continue to make purchases from his company as I always have. He and I spoke last week. I explained my bench test results and how I tested them. We talked about my test setup, and although not a perfect test and measurement procedure, I stated that I needed to do something with the tools and resources at hand. I was getting really tired of swapping senders in that FI manifold for fear of damage.

Now why I have 2 K&B senders here that failed is in my mind simply explained. Bad luck. Don't laugh. I have had a rash of unexplained failures lately.

If you followed my Voltage Regulator thread, I had not one, but two bad brand new Napa VR's. I tore my rebuilt generator apart to verify the armature and field coils. I tested the armature on my growler..... PASS. I tested the Field Coils again.... PASS. I brought NAPA VR#1 back to the store with my VOM and showed them the failure mode. Quite simple, 2 of 3 solenoid relay contacts were corroded and open circuit in the Normally Closed positions. Then they took another off the shelf. Same exact failure. Both VR's were in open, unsealed boxes. Both failed. They both came from the Miami Distribution center. I suspect they both sneaked out of their warehouse and spent the night on South Beach and crawled back before the warehouse reopened. That day that I had the 2 bad new VR's, my Napa store then sent a driver to their sister store a hour away to get another VR. It was delivered to me that afternoon. I bench tested it....PASS. I put my generator back together, put it and that 3rd VR in the car.......PERFECT.

So these 2 K&B senders were made just for me. Maybe the only 2 out of many that are out of spec. My luck had run out. I've realized it's just a fluke. However, a more conclusive assembled test may be needed to screen out marginal parts. I suggested that to Ken. After spending 30 years in the electronics test and design industry, what we didn't include in a test procedure usually failed at some point in time. We simply added new tests and moved on.

I got the one sender from NAPA as a last resort based on good posted results, and using the identical test procedure....PASS. Same with the 2nd one I got the other day to also get a reading at 210* to see if within their published spec and posted test results above......PASS.

Rich

[Patrick S.]

Re: C1 Reproduction Temperature Senders

How do you test the temp GAUGE? Thanks, Pat

[Richard M.]

Re: C1 Reproduction Temperature Senders

How do you test the temp GAUGE? Thanks, Pat

Pat, Reference Post46 ....

If you ground the sender wire(0 ohms), it should peg the meter.

105 ohms between ground and the sender wire should yield apx 180* on the gauge. I use a potentiometer, set it to 105 ohms using the meter, then connect the pot to ground and sender wire. Ign on, then check reading on gauge.

Rich

[Bob W.]

Re: C1 Reproduction Temperature Senders

Rich With it all said and done for cars not being judged what sender would you buy? Also do all small blocks use the same sender?


Thanks Bob