Temp Gauge Accuracy

[Deleted User]
[Deleted User]
edited August 2012 in HUDSON
In my pursuit to make sure I am overheating the engine, one person suggested that maybe my gauge is not as accurate as one would hope.

I have to warm it up with the cap off the radiator and test the coolant.

That being said, where on the gauge should the needle be for 180-190 while at idle, sitting in the driveway with NO extra fan and the hood RAISED?

How does one adjust the gauge it is determined to be off or would it be the sender that is more than likely the problem?

Comments

  • bob ward
    bob ward Senior Contributor
    There are no user adjustable parts within the temp gauge. The temp sender needs to be of the correct ohm range for the gauge to read properly, I have measured a Hudson one in the dim dark past and I think the sender went from 0 ohms to 35 ohms cold to hot. Someone may need to correct me there. There are many senders out there that will happily screw into that hole in the head, if you have the wrong one it is going to throw your gauge reading out.
  • RonS
    RonS Senior Contributor
    Borrow or purchase a inferred thermometer. These are battery powered and send a red beam to what ever you point it at. Aim it at the thermostat housing and the top of the radiator cap. This will give a good avg water temp reading . Car should be of course fully warmed. See where the gauge pointer sits. On my Hornet, the needle is a needle thickness to the right of center at water temp 170, at idle air temp of 90. The cap,if pressurized, should be on. These are a great tool for many things including brake repairs. BTY what year and model ?
  • [Deleted User]
    [Deleted User]
    RonS: I have the OE Temp Sender in my 50 Pacemaker Deluxe. I will find an inferred thermometer to use.

    Bob Ward: NAPA shows a TS6153 that is supposed to work. Since there is no "zero" set screw on the gauge, I will check the ohms on the gauge - screw to ground while running and warm should do it right?
  • 53jetman
    53jetman Senior Contributor
    P500 - Why are you running a 180 -190 t-stat? Since I don't drive my Hudson in the winter months, I run only a 160 t-stat and my temp gauge never goes over 1/2. These old inline sixes do not have to run near the same temps as modern engines.
  • [Deleted User]
    [Deleted User]
    Yes , cooler the better ,
    Roger
  • kamzack
    kamzack Senior Contributor

    Been told by Dr. Doug, the Hudson gauges are not accurate and not to panick if gauge show hot. The typical theory is if it isn't pushing coolant out the overflow, don't worry.
    I'm sure you have, but be sure you have good flow through the core and tanks. I run an electric fan in front of the rad and no fan on the pump, no problems. In traffic when temp starts rising, I flip the fan on and brings temp down to midway.
    Kim
  • lostmind
    lostmind Expert Adviser
    if you find you aren't overheating,but your gauge runs high, you can install a resistor inline .
    It would go in the wire from the sender to gauge.I would guess a starting point would be 5ohms?
    I thought the desired thermostat was 170 degrees. Always worked for me , and the gauge usually showed to the right of center when warmed up
  • hudsonguy
    hudsonguy Senior Contributor
    I believe most of the original gauges read hot, at least on my car that's the case. I've got an aftermarket Sun temp. gauge that will show it to be about 165 at idle (I use a modern 165 degree thermostat with one of Walt M.'s modified outlets, and an aluminum radiator) while the original gauge is almost pegged all the way to the right!
  • [Deleted User]
    [Deleted User]
    Great! This is helping me a lot. I think once I get a digital thermometer next week, I will know more.

    I have a modern 165 degree thermostat and one of the modified outlets as well.

    With the problem I had before (lose head bolt) - I am overly cautious I guess. I want to know exactly where I am at with temps, pressure, amps, RPMs, etc.........

    ......all so I don't damage an engine.
  • [Deleted User]
    [Deleted User]
    So let me re-phrase my question.

    In a "perfect world," what temp should the coolant be using a digital thermometer at the housing, gauge needle dead center middle, engine idle at proper RPMs, ambient air temp 80 degrees F?
  • RonS
    RonS Senior Contributor
    edited August 2012
    The water will begin to circulate when the water reaches the designed temp, if the stat is in good working order. In your case 165. Most guys like the 160 tstat, but 180 is fine. Once the coolant in the engine starts to circulate for a while ie, after the stat opens , a laser check can confirm the coolant ( water) temp is close to the factory setting. Now check where the gauge needle is sitting at that time. Keep it in mind, like Kentucky windage, AS was stated earlier, close to center is fine, but will probably be a slight bit to the Hot side.
  • [Deleted User]
    [Deleted User]
    RonS: That is my plan next week once I get back from my 28th Anniversary trip. The Army was kind enough to let us be together this year. We are up to 14 together, 10 a part due to Uncle Sam.

    LostMind: I understand add the resister in line. I can do that and there is a Radio Shack near here.
  • RonS
    RonS Senior Contributor
    Know what you mean. I spent my honeymoon at Ft Bragg, 40 years ago next week.
  • [Deleted User]
    [Deleted User]
    Opps....I missed a few of the aparts and togethers. I will need to go back and check my calendars. I wonder where those other three have gone?
  • [Deleted User]
    [Deleted User]
    Does anyone know the correct sending unit for the 308 in a 55, I was told TS 6464 but still showing real hot when the engine isn't.
  • SamJ
    SamJ Senior Contributor
    You can use a regular meat thermometer to test coolant temperature with the rad cap off. I wouldn't recommend taking the one out of your wife's kitchen, though... :-c
  • [Deleted User]
    [Deleted User]
    I know what the engine temp is what I don't know is the correct sending unit, any help will be appreciated
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