{Chrysler 300} Chrysler 300 64 temp units & Gauge

On Mon, Jun 29, 2026, 2:29 PM John Grady <jkg@xxxxxxxxxxxxxxxxx> wrote:

Carl is right, the same applies to the so-called reproduction fuel senders from Van's and others—they are all selling the same one. Reading above F, adding ohms will fix that and coincidentally help a little bit at low end, which tend to read near E with 1/2 atank . Resistor has most imapct near F will not fix E withought greatly dropping F Since I have a lot of cars, I use little paper tags so I don't forget what's going on. Running out of fuel in the passing lane at 80 with twenty Hell's Angels type Harleys all around me taught me that lesson in Harrisburg PA on that bidge, many years back/. . . They did not think it funny when I started coasting to right ,at suddenly lower speed.

On Mon, Jun 29, 2026 at 12:59 PM Carl Bilter <cbilter@xxxxxxxxx> wrote:
For the '60 and up thermal gauges, I haven't found a modern replacement sender that will give a correct reading - they all read too high on the gauge, but easy to correct by adding a 10 ohm resistor in series with the sender. For 60-62 this will yield a reading at or just above the first mark on the temp gauge at 180 degrees, which is about right. For 63-64 it might read a little higher on the gauge, or you can just add a bit more resistance. As John said, the reading on the temp gauge not as critical as fuel; however, seeing the needle always up near "H" is a bit unnerving. Always use an IR thermometer at the stat housing or radiator cap to verify actual coolant temperature, then note where the gauge reads at normal operating temperature.

Carl

------ Original Message ------

From "'JIM KRAUSMANN' via Chrysler 300 Club International" <chrysler-300-club-international@xxxxxxxxxxxxxxxx>

To "dave mason" <forwardlook300@xxxxxxxxx>; "John Grady" <jkg@xxxxxxxxxxxxxxxxx>

Cc "Chrysler 300 Club International" <chrysler-300-club-international@xxxxxxxxxxxxxxxx>

Date 6/29/2026 10:14:13 AM

Subject Re: {Chrysler 300} 64 temp sending units

A follow up on John's comments. Replacement temp senders for my C never worked right. Many sellers (including Goers) said they had the right one.
Long or short size, they weren't and read hot. Several years ago I found a vintage NORS unit (gas station brand) at a Carlisle vendor. It was labeled TS18.
It works great.
Jim Krausmann

On Thursday, June 25, 2026 at 02:46:04 PM EDT, John Grady <jkg@xxxxxxxxxxxxxxxxx> wrote:

That plug setup Dave M mentions is almost always the culprit in later mopars, and trucks. I had the issue in a '67 Dart; it drove me crazy.The pins are swaged into a PC card, (starts in 63?) the card shrinks , loosening all the pins ,which are only a mechanical fit used to make the electrical contact . Tends to be intermittent, not just gauges but panel lights etc
The only real cure is not too bad, but it takes some dexterity.
Get a small box cutter or "ignition file" and shine up both the pin , all around 360 at board , maybe 1/8" up --and copper trace near bottom of pin . Has to be shiny or next step goes no where. If solder does not take, due to oxide or dirt--- you now got youself a big problem, as you dont get try two, makes a mess of it. . Box cutter can make scratches like tight criss cross pattern of scratches to get at good copper
Get a small solder iron , maybe 30-40 watt, or I have done with weller 100 gun if careful. Solder each pin to the trace , fast and with tinned clean iron. rosin core solder like Kester, ,being sure to not push sideways on pin with iron which gets you a crooked pin , wont go into plug. Be very careful not to overheat card as it will lift copper off it
Bulletproof .

On temp senders,a cold temp sensor are like the fuel gauge at empty Resistance is about 70-80 -90 ohms,Like E on fuel,as both gauges are the same parts. maybe a bit more ohms, and obviously temp is less critical. If no ohms, (open) = bad will stay at C , if low or shorted will go to H or mid when cold
NAPA ones tend to be slightly wrong resistance , readingsa bit off . This info is thermal gauges only. 1960 up. Ealrier gauges with wound coils have ohms like 240 , big difference. A NAPA is better suited to FGH etc ; in a C or D will read up on temp scale when it's cold. Ours (F up) are close to stude, which also used Atwater-Kent thermal gauges ,
I know I could never get correct one for a 300C new, always wrong ohms, with a long story about I must be wrong its the gauge etc I finally took to pulling one off any mopar junk engine 57-59, plymouth dodge etc for 392. always worked , not sure about 56 back. Stude even in 1950 are about the same, 100 ohms , as 60 up mopar
Hope this helps,
J

PS, you have to take dash apart anyway, On Dart, to do this right , to get card out . That gave me the idea of get another card online or from a JY supplier , fix that one , shine where the lights twist in too , I put ba little silicone grease there . Avoids part of dash lighting going on and off , or one directiojnal not lightng..sometimes. I got one on Ebay for dart
Then you just swap it in.

On Thu, Jun 25, 2026 at 1:09 PM 'dave mason' via Chrysler 300 Club International <chrysler-300-club-international@xxxxxxxxxxxxxxxx> wrote:
Run a ground jumper from the “S” terminal on fuel gauge (or, ground the wire at temp sender end) for a few seconds only and you should see your temp gauge go up, provided the gauge is good and it’s getting 5.5V from the fuel gauge limiter (output on fuel gauge labeled “A” with the copper strap you mentioned).

Many times the 5-pin connector on back of instrument cluster gets loose or pins are tarnished, not saying this is your case, just info for the archive if someone looks this thread up.

Recently had an old temp sender go bad, first time I’ve ever seen that happen. Replaced sender (just a variable resistor) with one from Napa and problem solved.

D&K

Sent from my iPhone

On Jun 25, 2026, at 11:31, David Dumais <ddume300@xxxxxxxxx> wrote:

I have 3 sending units that thread into
W/pump housing.

No China or US stamped on any.
1 is stamped 250 with KS j3,

Another has no stampings.

And one has KS B4 and 250 all stamped
Twice .

All stamping are on hex faces .

Any thoughts on correct unit for the 64
Application?

Also, the voltage regulator stud has the copper ribbon squeezed tightly to it

I have to remove cluster again to verify
It.

I used the 12 volt needle test light between sending unit and the plug on end of violet gauge wire.

It flashed intermittently and not a steady light signal

NOS temp gauge not registering yet.

All pins and board copper have been gently cleaned.

Any thoughts?

Thanks
Dave D

Thanks Dave

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