Update: 195' thermostat makes no difference at all (I didn't really think it would) My car gets to 176' and stays there. I drove for 60 miles @ 55mph yesterday 33' outside and it never got above 176'. I am reinstalling the OLD original thermostat, because it warms up noticeably faster with it then any other one I have installed.(but still doesn't get Hot)
I am just at a loss to why this car is running so cool.
Thanks for everyones comments! -Dan

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1964 Dart GT

Other than the heater not blowing hot, it is better to run a little too cool than a little too hot, just means the cooling system is in good condition. If you have a fixed fan or a flex fan on it you may benefit from an electric. Then the fan will only run when it is hot enough, and you wont have air constantly flowing across the radiator and it will help keep the temps up...

With no fan that is very true ......mine warms up very quickly and is up to temp 195 degrees with in 2 miles from the house at 50 mph. The choke completely kicks off at the one mile marker.

Mine is timed at 12 degrees initial and I run mid grade gas. The lower octane fuel has too much water in it out here.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

It is better to run at the correct temperature and, if the engine doesn't run hot with a 160°F thermostat, it certainly won't with a 195°F thermostat. Heat transfer improves with a greater difference in temperature between ambient air and engine's cooling water.
There is ALWAYS air blowing through a radiator from the forward motion of the car. A flex or electric fan reduces the parasitic load on the engine at higher rpms (flex) or vehicle speeds (electric).

A thermostat's job is to REGULATE engine temperature by remaining CLOSED below its rating or by progressively opening with increasing temperature above its rating. Once a thermostat is FULLY OPEN (any temperature rating), heat transfer through the radiator (related to air flow & temperature difference) and water flow (RPM-related) is what determines how hot the engine runs.

If your thermostat is working correctly, there should be practically zero flow through the radiator below its temperature rating. Therefore, there is no way for an engine to warm up faster (ie, degrees per minute) with 195° thermostat than a 180° or 160°.

Unless your slant six is somehow magically much more thermodynamically efficient than everyone else's, the water jacket will be absorbing the same amount of waste heat as everyone else's engines and that heat has to be rejected somewhere. If your thermostat is good and the engine is cooler than the thermostat's rating, either your temperature measurement is incorrect or water is leaking past the thermostat. The thermostat MUST be correctly seated in its housing to seal properly.

If you have a 180°F thermostat in your engine and it "barely" reaches 180°, it is still reaching its rating. If it's only reaching 176°F, that 4° difference could still be within the accuracy of your gauge and the tolerance of your thermostat.

• The heater hose originating beside the thermostat (heater core supply) should be the same temperature as the engine.
• The heater hose connected to the water pump (heater core return) should be cooler than the supply hose when the heater fan is running.
• The upper rad hose should be close to engine temperature.
• The lower rad hose should be much cooler than the upper hose.

Does this car have air conditioning? If so, is the water valve to the heater core fully open?

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1965 Plymouth Barracuda,
225 engine, Quadrajet, HEI, Dutra Duals, 904 Torqueflite, 2.76:1 axle, Addco front bar
Rods & Relics - Fort Erie, ON / Collector Car Tech

yes, running at the correct temp would be ideal for everybody, my point was its better to run a little cooler and have the downside being low thermal efficiency, a little extra sludge build-up and possibly fouling some plugs if temps really do stay too low...

Yes it actually should run hotter with a 195* (not warm up faster) because the coolant will flow through the radiator less often, and not be cooled off. As long as the thermo is closed engine temps will continue to rise until the point of engine failure, on the other hand, no thermo, or one that doesnt seal will cause it to run a little on the cooler side, and take forever and a day to warm up because the coolant is constantly cycling through the engine and radiator...

For the fan, an electric will help very slightly with warm-up, also will running a leaner mixture when the choke is on, also will running a slightly higher timing, all of wich increases cylinder temps, wich in turn increases coolant temps. A fixed fan will be pulling air at all times, all vehicle speeds, and all rpms, and electric will ONLY run when temps are right or you manually turn the fan on. No cold air past the rad, and no cold air blowing against the engine itself, both will slightly shorten warm-up time.

For the thermo, yes it regulates the coolant flow based on temperature. Unlike an on-off switch it doesnt just fully open and fully close, it will gradually open allowing small amounts of coolant to flow, and gradually close as the cooler fluid cylces from the rad back into the engine. If engine temps still rise faster than the rad can dissipate, the thermo opens more. All this keeps engine temps consistant...

As far as actual warm-up time, every car varies just a little. Like I mentioned earlier, air/fuel adjustments as well as timing will play a big roll on engine temps as well.

Sounds to me like you need a better temp gauge so you know what the temps really are rather than "this one feels hotter than the other" If you have a 195* thermo, you should see an average of about 200* on your temp gauge depending on where your sensor is (engine temps are different in different locations of the engine as well as different from the radiator temps) You WILL NOT see the same temp front to back, hose to hose, top to bottom. Youll even see a small diff in temps from one side of the radiator to the next...

If temps on the engine are right, check and make sure the blend doors on the heater work and seal the way they should, if equipped make sure the heater control valve is opening all the way, maybe the heater core itself is clogged... This goes for ALL cars, years, makes, and models, not just our slants.

Im sure youll get it figured out, and just keep in mind that it is still more important that the cooling system remains consistant, not just how fast it warms up or cools off, but that it keeps all parts of the cooling (and heater) system a relatively equal temp...

Bad phone pic, I was driving at the time.(engine had been running 30 minutes.,only 45-55 mph)

Gauge works fine.(I have tested it with a cooking thermometer.) I am beginning to think my cooling system might just be working too well. I only have (2) radiators, both of which came from A/C equiped cars, both fans are 6 blade fans(each different shape), and I have the shroud for the fan also. On an off suggestion from a friend, I covered 1/3 of the radiator in front with cardboard and the temp went right over 180' on my commute ,but I still have the 195' thermostat in. I will change the thermostat back tomorrow and see what happens.

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1964 Dart GT

Block off part of the radiator with cardboard and see what happens.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

If you have a 195°F thermostat, your engine should not be running below 180° once it is fully warm. If you can raise the temperature by blocking off part of the rad, that tells me that there is either a lot of water flow leaking past the thermostat or the thermostat is defective. The fact that it takes a long time to warm up confirms this.

I have a 195°F Stant Superstat (PN 45359) in my car and it works well. Stant advertises that the stronger spring and power piston in their SuperStatensure better temperature control and faster warmup. Rock Auto lists this thermostat for $4.53.

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1965 Plymouth Barracuda,
225 engine, Quadrajet, HEI, Dutra Duals, 904 Torqueflite, 2.76:1 axle, Addco front bar
Rods & Relics - Fort Erie, ON / Collector Car Tech

Were did you install the sensor probe for that temp gauge? Is it in the engine by the thermo? Plus don't be surprised to get a bad "new" thermo either. Its not very common with Stant but its not impossible either. I have to agree that the thermo is bad or not in correctly if it truley is a 195* and your still not even getting close.

(3) Bad new thermostats? ((2) 180 & (1)195) all Stant.( I am doubting this.)

The gauge is in the same location in the head as the factory gauge(just tapped larger).

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1964 Dart GT

Danarchy: That is an old trick truckers (they actually have a zippered cover that fits over outer radiator grill), and others use up here in cold country.

By reducing size of radiator with cardboard, you are throttling its cooling capacity. Throttling cooling rate is also controlled by thermostat as previously discussed. I think that your thermostat is not fully closing, and or prematurely cracking open, and or is slower than normal to react to temperature swings causing lower engine coolant temperatures.

I see you are from Texas, and I know that temperatures have been on the cool side for that neck of the woods lately. What is normal during cold ambient temperature conditions is long warming cycle for coolant in radiator. During cold weather once thermostat cracks open coolant enters water jacket at a very cold temperature, and drops water jacket coolant temperature very quickly. Instead of pumping summer time 80 degree coolant from radiator, it getting 20 degree (or whatever ambient is) coolant, a much greater delta T (temperature differential), than you are accustom to, and it takes a long time to warm up the radiator coolant at these conditions to smooth out the thermal swings in water jacket. Thermostats are slow to react to quick temperature changes because they have mass, and allow a few seconds of excess cold coolant flow into water jacket that shocks the system.

This morning we are at 7 degrees above the doughnut, it will take 15 to 20 miles of driving ~40 mph to fully warm an engine, and its cooling system. I have oil temperature readout on my 300C, and yesterday at about 16 miles its oil reached 190 degrees with ambient temperature at 25 degrees. The bigger the coolant’s delta T between ambient and operating temperature, the slower the engine and related drive train warms up.

I recall one -33* morning after a winter scout camporee in northern Maine my old Crown Vic very reluctantly started running first on 2, than 3, than 5, 6 finally all 8 cylinders, sitting on its foam seat that felt like concrete, and after driving 30 miles to brother-in-law’s house the car just began to blow lukewarm air. It was another 50 miles before the engine got close to operating temperature to blow hot air from heater.

I know you aren’t going to see a delta T of 223 degrees like the old ford did, but it is not unreasonable for your engine to occasional see a delta T of 165 degrees (@25* ambient, 190 stat) when the jet stream dips south.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

My thinking on installing the 195' thermostat was that the engine might get hotter before the thermostat started to open. It didn't, it ran just the same as with the 180' thermostats. I have always thought that a thermostat would not start to open until the water reached the designated temp. rating. It seems as if mine have been opening slightly(not fully) before the rated temp., and either opening and closing, or staying open to keep the temp.low.(?)
I mentioned to someone that I had an old chevy(194 straight 6) and the temp. gauge needle would bounce when the thermostat opened, but a slant would not do the same thing due to the placement of the temp. gauge sensor. I plan to place the original dash gauge sensor in a thermostat housing, so I will get a reading on both sides of the thermostat. Hopefully this weekend, if the weather holds out.

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1964 Dart GT

That is the supposed to be the way it works. See "How does a thermostat work?" and "Why doesn't the passenger compartment in my car heat up?".
http://www.stant.com/consumer-products/thermostats/faqs


The thermostat in the engine works like the one in your house but opposite. Below its rating, the thermostat remains closed to keep heat in the engine. The one in your house turns the furnace on when the temperature is below its setpoint. In either case, the engine thermostat cannot be more CLOSED and the furnace cannot be more ON.

In your situation, with the engine taking longer to heat up because of leakage to the rad, it is a lot like trying to heat the house with the windows open. Closing the curtains helps (like putting cardboard in front of the rad) but you really need to close the windows.

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1965 Plymouth Barracuda,
225 engine, Quadrajet, HEI, Dutra Duals, 904 Torqueflite, 2.76:1 axle, Addco front bar
Rods & Relics - Fort Erie, ON / Collector Car Tech

Yea its very unlikely to have three in a row that is bad. Really probably is just the fact that the cooling system is just doing its job and as mentioned above, when the ice cold coolant from the radiator begins to make its way into the engine it dramatically drops the coolant temp of the engine.

On mine, I have the factory sender in the stock location, and added my aftermarket one in the very front of the head (there was a pipe plug in the hole I had to remove). I see about 15-20mins of running/driving time on mine before it shows full temp on the gauge and the heater starts blowing hot, but it stays very consistent at about 198* once it is warm (20*-30* mornings)

You may just be one of the lucky ones (or unlucky) that the cooling system is efficient. Some cars temp gauges do bounce around a lot and some are steady, I have found that the factory one will peg full hot after the engine is off for a minute and turned back on but immediately comes down, and the aftermarket one will only rise a tiny bit (maybe 5*). On the other hand my 1989 Golf, the gauge is all over the place, you can watch it and see when the thermo actually opens, as well as watch it drop as the fan runs... That car with a 195* stat will average 200*-220* degrees when its running... but still takes about 20 min to reach operating temp on cold mornings as well. Both have fresh engines, new radiators, all new hoses and water pumps, thermos, etc...

Where are your heater hoses connected? Can you post a pic of them?

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Mattelderca
78 NYB (gone now), two S series, three old Snow Cruisers and a Doo.