Tom and Royce you are both correct. My point is that the measurement in the circuit the resistance will be a bit lower. Tom is correct that the current through the meter is too low to have an effect, but in the circuit where there is more power flowing through it it may make a difference. I suspect that 22 ohms might drop to 20 in circuit
I found this Autolite temp sender in a box of stray leftover parts - can’t say I know for certain where I got it. The insulator is more purple than red. It is stamped “Autolite 2309G.” Anyone know what I have here?
Bill - I’d be willing to send this to you for testing. If it is correct for '69 CJ, though, I’d want it back when you’re done. PM me if interested.
I am building a new test bed to do these. Please sent it and I will test it. I found a little hot plate that I will use to heat water to test these. I will run them in the circuit and then use the current and voltage across the device to calculate the resistance. I also want to do meter readings to see if they are significantly different. I will be a little slow as it is in the mid teens in my shed… like 115 117…
Royce, (and everyone else!)
You saved me again. I bought a new sensor from WCCC. Right out of the box I checked it with my ohm meter at room temperature. It read 163 ohms. I tried it in my 390 Cougar XR7. The exit point from my house to the ‘hard road’ is exactly one half mile. In that half mile traveled, the needle in my temperature gauge was already two thirds of the way over. Another mile down the road, the needle was over very near to the red hot line. No Fix.
So I was going through some old stuff in my garage and found an old Autolite sensor. It was marked ‘Autolite 260 8E’ The top of it was a light orange color. When I checked it with my ohm meter at room temperature it read 268 ohms. I immediately installed it on the old 390. Yesterday here in central Florida with a temperature of 94 degrees, with the A/C running, and driving the car for almost an hour, the temperature gauge needle ran vertically for the entire time. When I shut the car off, the needle moved about two thirds over but never got close to the red line hot part of the gauge. Starting the car again, the car cooled down again and the needle went back to running vertically again. I call this a fix.
Thanks everyone!
I recently found a Motorcraft C6DZ 10884-B on eBay. It has a purplish insulator material. It checks out when tested like the others. Stamped Motorcraft 260 on the side.
So I went to O’reillys. Bought the Standard (that’s the name of it) temp sensor with life time warranty.
Installed it this morning. Warmed up the engine. Took it on a short highway run. Gauge held steady between the T and E
Outside temp about 30 degrees
Going on longer trip this afternoon. Will wait and see what happens.
I did the same resistance comparison as Royce with very similar results. Never did find a parts store sensor that was correct for my 351c, so got an NOS temp sensor that works great. My NOS unit also measures 300 ohms at room temp and 30 ohms at 200 deg F which reads at 1/2 on the original dash temp gauge. I lost the box, so don’t have the Autolite P/N.
Coming back from Auburn to Truckee there was one stretch of uphill climb where my gauge went just a little ways over the P.
Turned the heater on and it dropped to just below the P. It was pretty cool outside as well.
It may not be accurate but I believe this will give me a good idea of what’s going on temp wise.
I know I need a new radiator and also overflow container as well.
Hope this is helpful
Just another follow up
I took a 30 minute ride yesterday.
90 degrees outside.
Some moderate hills. Cruising about 60.
Went just a little over the P.
I think it’s giving me a accurate idea of what’s going on.
I’ll try and get some more definitive numbers in the next few weeks.
I’ll add my experience with aftermarket temp senders reading high. Recently tried 2 different senders (Rock Auto and NAPA). Both read high.
Found the correct sender on Ebay (NOS Ford part DOWY 10884A for my 351C). It wasn’t cheap at $119 but it works correctly as confirmed by infrared temp reader. Ebay seller is LunchPailParts.
Standard Motor Products has been around since 1919 they had a 6 story building about a block long in Long Island City NY. They are now in Greenvale SC
some of there parts are still supposed to be made here. They made all kinds of ignition parts, sensors, carb kits and more. They may have been a OE supplier at one time.
With all that experience it’s too bad they don’t know how to make a temp sensor that works.
Looking to replace the temperature sensing unit for the gauge on my 1970 351C. My prior searched a few years ago found MotorCraft SW925, SMP TS58 and NAPA TS6628. Now I’m seeing a lot of MotorCraft SW2328 and SMP TS25 references. I question whether these are correct, has anyone had any experience with these. The older ones a seem to match the readings on my Holley Sniper so I’ll stick with them unless someone has better information.
BTW I finally found the source of my highway overheating, the block was bored 0.060 over. Working on that now and considering changing the temp sensor in the rebuild.
I tried 5 or 6 aftermarket ones for my 351C but had to go with an NOS unit I found on eBay to get correct readings.
Silly question - why does oversized bore cause overheating? Is it the loss of iron needed to transfer the heat, or just due to that much larger surface area to cool?
My understanding is that the inter-bore material becomes extremely thin, allowing more heat conduction into the water jackets vice having the block retain the heat.
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Thanks - that makes sense. And the Cleveland was thin around the cylinders already.
Here is temp curve data on a NOS Motorcraft SW924 D0WY-10884-A (which I believe is correct for a 70 351C) that I just picked up on eBay:
Temp Resistance
70 deg 320 ohms
80 deg 260 ohms
90 deg 220 ohms
100 deg 190 ohms
110 deg 150 ohms
120 deg 130 ohms
130 deg 107 ohms
140 deg 91 ohms
150 deg 77 ohms
160 deg 65 ohms
170 deg 54 ohms
180 deg 46 ohms
190 deg 39 ohms
200 deg 33 ohms
205 deg 30 ohms (normal operating temp for my car)
210 deg 28 ohms
212 deg 27 ohms (boiling)
258 is stamped on one flat (resistance at ambient or maybe supplier number?) and K (October?) on another. Very linear and smooth changes in resistance as water heated up like Royce saw on his Motorcraft sensor.
I had issues with the “replacement” sensor in the XR7 I bought. Found a NOS on Ebay recently. No bids, surprisingly, so I got it for $86oo. As it completely cured the problem, I consider it a bargain.