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Temp Gauge Shows HOT - Engine Is Not
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Author:  ptretrorod [ Mon Jul 17, 2006 5:53 am ]
Post subject:  Temp Gauge Shows HOT - Engine Is Not

Hi,

I just bought a 1961 Dodge Dart with the slant 6. I have been driving it back and forth to work daily for the last few weeks 10 miles on the interstate each way. Great car, great engine with a couple small problems. The biggest is the cooling. It was running hot according to the temp gauge, so I replaced the thermostat. Still shows hot, removed the thermostat. Still shows hot, replaced all the hoses clamps water pump, radiator, flushed the block and the heater core. Still shows hot. The temp gauge slowly climbs to the hot side after about 5 miles on the interstate. What should I do now?

Thanks in advance!

Author:  SlantSixDan [ Mon Jul 17, 2006 6:02 am ]
Post subject: 

Welcome onboard.

What type of thermostat did you install? Many books list 195° as the correct temperature, which is not correct; 180° is.

Assuming a correct thermostat, your trouble could be caused by a faulty temperature gauge sender, which is an easy swap, so you may want to install a new one of those—make sure you get the correct one, Standard # TS52 or NAPA Echlin #TS6463.

Thinking further, does the gauge indication go back down if you get off the interstate and let it idle? Or does it remain "H"? Have you verified (as with a thermometer in the radiator top tank) that coolant temp is normal?

Author:  ptretrorod [ Mon Jul 17, 2006 10:08 am ]
Post subject: 

Hey cool car in the pic. I installed a 160 degree thermostat after reading some tips on this site. The temperature does go down slightly after getting off the interstate and taking back roads. I have not checked the actual temperature yet but plan on that next. Then get the coolant temp sending unit if everything checks out. Thanks for the part numbers. Your help is much appreciated!

Author:  SlantSixDan [ Mon Jul 17, 2006 10:21 am ]
Post subject: 

A 160° thermostat is not a good idea; all it will do is reduce your fuel economy and engine life. Use the correct 180° unit.

Author:  argentina-slantsixer [ Mon Jul 17, 2006 3:57 pm ]
Post subject: 

Quote:
A 160° thermostat is not a good idea; all it will do is reduce your fuel economy and engine life. Use the correct 180° unit.
and you're the man who sez that proper recommendations can be given with plenty of information! a 160º unit is good for some applications and not the best choice for others. :wink:

Author:  SlantSixDan [ Mon Jul 17, 2006 4:00 pm ]
Post subject: 

Well, sure, but what we're talking about here is a stock or near-stock daily driver, which means...

...180°.

Author:  Orange72 [ Mon Jul 17, 2006 4:55 pm ]
Post subject: 

180* has always worked for me, stock engine or built. Have you checked your timing lately?

Author:  mopardon [ Mon Jul 17, 2006 10:43 pm ]
Post subject:  160 stat n/g? Oops!

How does a 160 (summer) stat reduce fuel mileage and, most importantly, engine life? I did not know that 20 degrees (I can't find the mark on this TRS80) made that much difference. With a new rad, sending
unit, and 180 this Aspen edged toward H whenever the outside temp
was near 80 in stop-and-go. I figured that I could just block part of the rad to increase temp. a bit if needed.

Thanks

Author:  ptretrorod [ Tue Jul 18, 2006 4:18 am ]
Post subject: 

I went to the local auto parts supply only to find out that Autozone uses a Wells temp sending unit p/n TU-22 which is no where close to the one I need. It was smaller, I could drop it through the hole in my engine, plus the connector was a threaded rod vs. mine has a flat round top on it that my connector slides around.

Napa says they can get me one in a day for 10.49. I dont know until it comes in if it is correct either.

Can anyone explain to me how this thing could have gone bad and be showing too hot? I normally understand when it quit sending a signal at all, but this perplexes me.

I have not checked the timing, though right before all this happened, I messed with the carb a bit to get it running better, but other than that, I havent touched anything. The carb is a single barrel. My car was puttering and idled high, so I slowed the idle down, and adjusted the screw on the bottom of the carb as instructed, turn clockwise until the car wants to die, the turn left half. It seems to run great now.

I have not checked the actual temp yet either, I can say that my radiator is not overflowing so I consider that a good sign, and yes, I beleive that the cap is good.

Thanks for all your help on all the threads!

Author:  SlantSixDan [ Tue Jul 18, 2006 6:52 am ]
Post subject:  Re: 160 stat n/g? Oops!

Quote:
How does a 160 (summer) stat reduce fuel mileage and, most importantly, engine life?
See here.

The notion of a 160 "summer thermostat" is left over from the 1950s.

Author:  SlantSixDan [ Tue Jul 18, 2006 6:58 am ]
Post subject: 

Quote:
I went to the local auto parts supply only to find out that Autozone uses a Wells temp sending unit p/n TU-22 which is no where close to the one I need. It was smaller, I could drop it through the hole in my engine, plus the connector was a threaded rod vs. mine has a flat round top on it that my connector slides around.
Right, that's the '64-up sender, which not only won't fit but won't work with your '61 gauge. Get one of the ones I called out by part number, and it will fit and work.
Quote:
Napa says they can get me one in a day for 10.49. I dont know until it comes in if it is correct either.
Well, if it's an Echlin TS6463, then yes. If it's a TS6178 ('64-up sender), then no. :-)
Quote:
Can anyone explain to me how this thing could have gone bad and be showing too hot? I normally understand when it quit sending a signal at all, but this perplexes me.
It's an element whose resistance varies with temperature. If the engine was ever heated up (not even severely overheated), this can throw off the calibration of the variable resistor. They had a few problems with the OE sending units in '60-'61 not making the gauge read where it should...customers were coming back to the dealer complaining of overheating which didn't actually exist...the initial fix prescribed by the factory was for the dealer to install a plain resistor in the sender wire, and tuck it out of sight, to reduce the gauge readings for any given coolant temp! Eventually they released a revised sender and customers got that one.

One further question: How accurate is your gasoline gauge?

I have not checked the timing, though right before all this happened, I messed with the carb a bit to get it running better, but other than that, I havent touched anything. The carb is a single barrel. My car was puttering and idled high, so I slowed the idle down, and adjusted the screw on the bottom of the carb as instructed, turn clockwise until the car wants to die, the turn left half. It seems to run great now.

I have not checked the actual temp yet either, I can say that my radiator is not overflowing so I consider that a good sign, and yes, I beleive that the cap is good.

Thanks for all your help on all the threads![/quote]

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