67 GTX 440 Engine Temperature With AC

67GTX440 · Aug 17, 2016

I live in Florida where the summer temperature is a consistent 90-95. Car has 195 degree thermostat, so runs 195 with AC off. I have been told by Classic Air to expect running the AC in hot weather to add 15 degrees to operating temperature. Car runs 205 to 210 degrees with the A/C on on a scorching day. New cars run these temps and may even have 205 degree thermostats.

Should I have any worry about this or is this a normal expectation for and A/C car in a hot climate? I am assuming going to a 180 thermostat would only reduce the time at startup until the thermostat opened since the car is running 195 with the the thermostat open and the AC off. Am I wrong about this?

Any responses from those with 67 440 A/C cars in a hot climate and a temperature gauge on what their car runs with A/C off and A/C on would be appreciated.

I see lots of "my car never runs above 180 degrees with a 180 degree thermostat", but not necessarily from someone with A/C in a hot climate.

lewtot184 · Aug 17, 2016

your car probably came from the factory with a 180 'stat. '68 and later had 195"s, which we all took out and pitched back in the day, for smog reasons. i'd do a 180.

PurpleBeeper · Aug 17, 2016

1. You can "get by" at 210F, but I would shut the car off at 220F and let it cool down. You are on the ragged edge of engine meltdown in my opinion.

2. You're right. Changing to a 180F themostat will make no difference & you will still run at 205F on hot days with the A/C on..... it just might not reach that temperature for an extra 3-5 minutes, but it will get there.

3. I STRONGLY suggest that you switch to Water Wetter / Purple Ice / Lucas Super Coolant / Hyper Lube & distilled water instead of 50/50 antifreeze. It will drop your engine temperature 20F-30F on scorching days with the A/C on. You can also run a combination antifreeze/"water wetter" product/distilled water.

How cold does it get in Florida on the coldest night of the year? Do you have aluminum heads and/or an aluminum water pump housing? PM me if you'd like me to give you the recipe for a custom-blend antifreeze that will make your engine run cooler. I also need to know your cooling system capacity to do that calculation for you.

terzmo · Aug 17, 2016

At 210 the factory heat gauge would be pegged. It's not a new car. My truck runs at 215 all day...that's the norm for a new vehicle,at least chevy. At 200 I worry...at 205 I shut mine down. 195 and lower is good...I run a 170 stat(stat is only an indicator of what temp it will let water flow) but on hot muggy days ,believe it or not,in WNY it runs at 188 to 190. 472 hemi....26 inch alum rad...6 blade steel clutch fan and schroud.

Now....previously some mopar people have stated they run their old mopars at 240..(hard to believe for me)..good luck with that. Been driving mopars for 50 years....old engines don't like heat. They will run and perform best at 185 plus or minus a couple.

super-bee_ski · Aug 17, 2016

Well, I guess it depends on the car

oldbee · Aug 17, 2016

"67"-- why not try a 160 t-stat first? I cringe at 200deg. You don't have a new-design engine; more air flow thru rad.? You're almost overheating eng.oil & trans oil if automatic!!

Dennis H · Aug 17, 2016

Run that much higher with ac on? No way. My car runs within 3 degrees with ac on or off. Yes if it gets hot you can cut the ac.

oldbee · Aug 17, 2016

Dennis H- I think that's where I was going.?? He needs more air flow thru condenser/radiator??? Fla. shouldn't need a 180 t-stat in my opinion.

Mike67 · Aug 17, 2016

Modern cars are totally different materials/alloys and are desgined to disapate heat quicker than older vehicles. I also know newer vehicles have provisions for relieving steam at those temps. Someone can correct me but old cast iron cylinder heads were not designed for steam... ????...I would think you would have to take into consideration of the design pressure of the cap, 15 lb vs 20lb cap will change the boiling point of water...Don't know what the effects are with an additive though...
I know I get worried at 210 in Texas...to help combat that I added a small pusher fan to my wife's car and it knocked it down about 10 degrees w/ a.c. on sitting in traffic...

oldbee · Aug 17, 2016

Mike67- that's what I was thinking. Maybe a 160deg. t-stat would help. My 68 w/180 t-stat heats up real quick on Ohio this summer(no a/c). Haven't really spent much time on the road. Find out next week when I take it out to my old workplace !!

AR67GTX · Aug 17, 2016

I had my radiator re-cored a couple years ago and in the process checked the numbers for it and found it was originally from a Chrysler New Yorker or something like that. So it may not exactly be typical. But my car runs pretty much the same on the dash gage with AC on or AC off and it's a factory AC car. It runs cool enough that I haven't even bothered to check it with an IR gun. I think I have a 180 thermostat in it. Temps in the mid to upper 90s are not rare in Arkansas in the summer.

One item I added to my car that you may want to consider was an idle compensator to boost the idle rpm when the AC compressor is engaged. It bumps the idle speed up to compensate for the load of the compressor which can't hurt cooling when sitting at a light. It also helps with the headlights at night when the AC is on. Makes the car a little more pleasant to drive.

I ordered it from Summit.

https://www.summitracing.com/parts/edl-8059

terzmo · Aug 17, 2016

Hey guys.....the stat is designed to block flow until it reaches design temp.....I run a 160 stat as I like the car to run cooler sooner than a 195 stat....A 195 stat will keep the car at 195 minimum..if it is running cool...it will stay at 195 on the gauge because the stat will close and block circulation...IF a car is running hot....the stat has nothing to do with keeping temp down....the stat keeps the car at it's designed temp or higher...My 160 stat opens but if it's a hot day...I run at 185 to 188 and the stat in these temps is open...The stat was used to warm cars up faster in the winter to get heat out of the system. You get no cooling flow if the stat is closed so the engine warms up quicker than no stat
If you are running hot down the road at speed...I'd look at the rad and lower hose..if hot in traffic and not down the road...the rad is not getting enough air to cool and could be pump...shroud.not installed properly with fan..etc

Ranger16 · Aug 17, 2016

67GTX440 said:
I am assuming going to a 180 thermostat would only reduce the time at startup until the thermostat opened since the car is running 195 with the the thermostat open and the AC off. Am I wrong about this?

You are running 195 because you have a 195 thermostat in it. The thermostat controls the operating temperature, not the amount of time it takes to open, although a higher stat may take slightly longer to go full open. Install a 180 and you'll run cooler. It's just that simple.

I see lots of "my car never runs above 180 degrees with a 180 degree thermostat", but not necessarily from someone with A/C in a hot climate.

I went from the 190 that was in it when I bought it to180 because it was running too hot. 200 on the highway and got to 230 in a Power Tour traffic back up in Madison in 2010. Never skipped a beat, but I was nervous. Changed the thermostat to a 180 when I got home and now run about 185, with an occasional 190.
All that said, I have a non A/C 383, but the principles are the same. You want to run cooler, run a lower stat.

As for the cap pressure, I would not even worry about it. Remember, that is simply the vent pressure. I don't know what the normal operating pressure is, but I doubt you (we) are running anywhere near it.

67GTX440 · Aug 17, 2016

AR67GTX said:
I had my radiator re-cored a couple years ago and in the process checked the numbers for it and found it was originally from a Chrysler New Yorker or something like that. So it may not exactly be typical. But my car runs pretty much the same on the dash gage with AC on or AC off and it's a factory AC car. It runs cool enough that I haven't even bothered to check it with an IR gun. I think I have a 180 thermostat in it. Temps in the mid to upper 90s are not rare in Arkansas in the summer.

One item I added to my car that you may want to consider was an idle compensator to boost the idle rpm when the AC compressor is engaged. It bumps the idle speed up to compensate for the load of the compressor which can't hurt cooling when sitting at a light. It also helps with the headlights at night when the AC is on. Makes the car a little more pleasant to drive.

I ordered it from Summit.

https://www.summitracing.com/parts/edl-8059

Good advice.

67GTX440 · Aug 17, 2016

I bought the new Hayden short shaft 2947 heavy duty thermal clutch designed for Mopar and will also spring the $5.00 for a new 180 degree thermostat and gasket. I will report back once I see if this makes a substantial difference. Shroud and fan blade all appear to be stock for a 67 with factory air. New water pump and 26" 3 row factory radiator just recored.

I am running out of things to try. I keep thinking about that thread where someone found an old misplaced freeze plug stuck in the block blocking water flow. You never know what an old Mopar has in store after 50 years of shade tree mechanical work.

TxDon · Aug 18, 2016

I have similar issues when running A/C in Texas and started a thread about it: http://www.forbbodiesonly.com/mopar...xas-cooling-adventures.115664/#post-910495174
The difference is I have an aftermarket aluminum radiator and aftermarket A/C. I found a much larger fan and am also considering the 2947 clutch to make it fit, so I will be following to see how it works for you...good luck.

67GTX440 · Aug 18, 2016

TxDon said:
I have similar issues when running A/C in Texas and started a thread about it: http://www.forbbodiesonly.com/mopar...xas-cooling-adventures.115664/#post-910495174
The difference is I have an aftermarket aluminum radiator and aftermarket A/C. I found a much larger fan and am also considering the 2947 clutch to make it fit, so I will be following to see how it works for you...good luck.

Very similar climate and issues on same car. I have the Hayden 2947 on order and am going to remove the thermostat to see what temp I get. Currently running straight distilled water with water wetter for anti-corrision since pure water dissipates heat better than a 50/50 water/antifreeze mix. Running factory fan and shroud, a 30 percent higher flow water pump and radiator was just recored. No real heating issues until I reinstalled the condenser and got he A/C up and running. Running a more efficient Sandin compressor.

Mike67 · Aug 18, 2016

Removing the stat completely might make it worse, in addition to getting the motor up to temp in cooler weather, it also restricts the flow slightly to allow ample time spent in the radiator as to remove as much heat as possible like T said. Does it boil over?
You might have answered this already but how close is the condenser to the radiator?...it still sounds like an airflow problem to me...

67GTX440 · Aug 18, 2016

Mike67 said:
Removing the stat completely might make it worse, in addition to getting the motor up to temp in cooler weather, it also restricts the flow slightly to allow ample time spent in the radiator as to remove as much heat as possible like T said. Does it boil over?
You might have answered this already but how close is the condenser to the radiator?...it still sounds like an airflow problem to me...

Does not boil over. There is about an inch or a little more between the condenser and radiator. Radiator is factory just recored, fan is factory, shroud is factory, thermostat is 195 that is currently shown as OEM in most part lookups although factory was 180. No overheating prior to putting AC back on. Classic Air said to expect 15 degrees diff with AC on. I am not sure if I am chasing a non problem or if this car ever ran any cooler when it rolled out of the factory in 1967. I have no idea what the normal operating range on the factory gauge has as a low and high. My factory gauge never gets to the top of normal operating range with the secondary temp gauge at 220.

Dennis H · Aug 18, 2016

I recommend Classic Auto Air to everyone, but cannot agree with the 15 degree statement. Be sure to use a Stant Super-Stat 180. No chrome housing.

67 GTX 440 Engine Temperature With AC

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