benefits of 160 deg. vs. 180 deg. thermostat - Vintage Mustang Forums

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post #1 of 30 (permalink) Old 05-27-2009, 11:12 PM Thread Starter
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benefits of 160 deg. vs. 180 deg. thermostat

I'm going to put a new thermostat on and was just wondering the wisdom of possibly ordering a 160 degree instead of a 180, which is what is on the car now.

Background - the car ran hot from the time I got it until it finally overheated because of a stuck thermostat. Upon fixing this, I found that the coolant was ancient and the system was only about half-full. I didn't have any problems until this spring, when I went on an 80-mile round-trip highway drive and had the temp needle slowly creeping up during the portion of that drive that was on an interstate. It was this that finally clued me in that I had a leaky radiator cap, and that it was the reason I had coolant blowback under the hood - not a leaky overflow hose or some other reason that I couldn't figure out.

I hadn't driven it much between replacing that and starting this project of changing my carb. It's a '65 convertible that I'm upgrading from a 2bbl to 4bbl.

Anyway, just trying to figure out if there's a benefit to using something other than 180. Thanks for the help.

1965 convertible, 289 C-code upgraded to 4bbl
1965 coupe, 200, T5 - daily driver
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post #2 of 30 (permalink) Old 05-27-2009, 11:22 PM
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This is what a few of us Californians use:

180 STAT
Coolant: 20+%
Distilled water: 80+%.
one bottle of water wetter.

Using this in the 50 Chebbie truck, 67 GTO and 65 Mustang

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post #3 of 30 (permalink) Old 05-28-2009, 12:01 AM
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Re: benefits of 160 deg. vs. 180 deg. thermostat

Engines run better at 185º - 195º. Never understood using 160º thermostat.


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post #4 of 30 (permalink) Old 05-28-2009, 01:15 AM
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A 160 degree thermostat is way too low. If you have an overheating problem with a 180 degree t-stat, then you need to find the problem elsewhere.


1967 Saddle/Burnt Amber coupe, C-code T5 5-spd replaced the 4-spd, 302 replaced the 289.
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post #5 of 30 (permalink) Old 05-28-2009, 01:31 AM
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It is definatley going to do is help you run a little cooler. I have a hypertech 160 deg thermostat in my 94 Police Intereceptor Camaro and it definatley helps that LT1 run cooler. But I also beat on that car every chance i get so it heats up alot quicker they also run warmer in general and my fan is not always running all so that also allows it to heat up quicker when im stuck in traffic. But if you are just cruising and not romping on the engine you may not need the 160.
Also how old is the radiator you have in your car right now? What kind of shape is it in ie are the fins all bent and broken on it or is the inside full of rust? If so you might need to upgrade your radiator. Just my .02 worth

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post #6 of 30 (permalink) Old 05-28-2009, 01:47 AM
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There area also I believe some thermostats that have a larger flow when opened. This should also help the heating problems.
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post #7 of 30 (permalink) Old 05-28-2009, 02:12 AM
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I switched to a 160* t-stat once, it was a waste of time. When it was cool out, the car would never heat up enough to run properly. Even after a 20 mile drive, the car still ran like it had just been cold started a few seconds ago. If your car is overheating, the 160 wont help at all. The temp is still going to climb past 160 which just the means the t-stat will open and stay open sooner.

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post #8 of 30 (permalink) Old 05-28-2009, 08:13 AM
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i have a 160 in mine

last summer it was creeping up in traffic with a 180 and stock fan but never to hot

i put on a plastic 90 degree blade flex fan from summit, kept it at 180 going down the road and in town

radiator was old 2 core and sprung a leak, put in a 3 core, and she started running hotter so had to add a shroud

didnt help in traffic, seems like the brand new 3 core ran hotter than the 2 core even with that killer fan from summit

thats when i went 160 and it helped alot but now it took a lot longer to get to get hot but still would

thought about buying another 2 core radiator

ultimately bought an electric fan setup that i could dial in the temp it kicks in at

with the 160 thermostat i have the fan kick in around 170 to around 180 that way she starts cooling a bit sooner (170) and it can creep up in traffic but hold it in a reasonable temp then when ya finally get out on the road you can see it come back to the 180-185 area

dont go the route i did

you dont want it to stay at 160, the motor needs to hover around 180 to 190

if the fan setup pulls good air and the coolant system is clean and the radiator isnt plugged up with crap outside stopping air from flowing through it freely it should be good with a 180

it sounds like your system was ok just neglected so do the coolant as mentioned above in another post and a 180, you will probably be ok


65 stang, 289, c4, 3:25 locker, dual exhaust, vintage wheels, all new interior
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post #9 of 30 (permalink) Old 05-28-2009, 08:17 AM
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Originally Posted by sycostang67
I switched to a 160* t-stat once, it was a waste of time. When it was cool out, the car would never heat up enough to run properly. Even after a 20 mile drive, the car still ran like it had just been cold started a few seconds ago. If your car is overheating, the 160 wont help at all. The temp is still going to climb past 160 which just the means the t-stat will open and stay open sooner.

I agree with you 100%. Once any themostat opens it will stay open till the engine cools back down to it's selected temp. So all a 160 does is open sooner than a 180. The engine is still going to heat up to it's running temp. And if it tends to run on the hot side it still will.
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post #10 of 30 (permalink) Old 05-28-2009, 08:20 AM
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Originally Posted by sycostang67
If your car is overheating, the 160 wont help at all. The temp is still going to climb past 160 which just the means the t-stat will open and stay open sooner.

Ding ding ding, we have a winner.

Many people don't really understand thermostats at all. If your cooling system is working properly, the 160 deg stat will open at approx 160 degrees allowing the cooling system to keep the engine about 160 degrees, too low for proper operation. If the cooling system is inadequate or defective, the cooling system won't be any more able to remove heat with the 160 stat than it would with a 180, 190, 200 etc.

However, a lower degree t-stat will delay an overheating problem (as pointed out above) during warmup by getting the coolant circulating into the radiator sooner than with a higher stat would. But remember, at temps above 180, both a 160 and a 180 stat will be fully open.


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post #11 of 30 (permalink) Old 05-28-2009, 08:25 AM
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Thermostats work the opposite way most people seem to understand them.

If you're car overheats with a 180 will still overheat with a 160 t-stat it just might take a little longer for it to happen. The car is overheating because the fluid isn't staying in the radiator long enough to stay at a constant temp in the system. All the 160 does is run your coolant at an artificially low temp when your system is operating properly and able to cool through the radiator. As soon as driving conditions change and the system is no longer cooling properly through the radiator (stop and go traffic, sitting at a red light with a fan that flow enough CFM, beating on the engine generating heat faster) your temps will increase. You may 'think' you have fixed the issue but all you are doing is starting the overheat creeping from 20 degrees cooler. It may 'mask' the problem for a time (like if you don't get stuck in any major traffic for a few months). The 160 is suitable for the winter when you have a heater core that will not generate heat until the t-stat opens and you have a cooling system that keeps shutting down the 180 on cold days.

If you are over heating with a 180, you should put in a 195 t-stat and/or solve the cause of the poor performance in the cooling system. In my case (since I have run 160, 180 and 195) in my car I can tell you my radiator is marginal at best in my 65 with my 410 stroker. Using the 195 t-stat did wonders to solve my creeping temp problems that occurred both in stop and go traffic and when driving aggressively.

To Mr. Bloom's original question, no you will not gain anything with the 160. It sounds like you solved your issues so just button it back up with a new 180 and call it done.

1965 Fastback 410c AOD - DT
1967 Fastback 347 T5- Cruiser
1968 Fastback 408w T5 - Brute
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post #12 of 30 (permalink) Old 05-28-2009, 08:49 AM
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When I bought my '66 the previous owner had installed a 160 degree thermostat. I replaced it with a 180 & kept the 160 as a spare. It is still in the bottom of my toolbox 9 years later. Even in Texas, the 180 works fine as long as the rest of the engine & cooling system is in good repair.


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post #13 of 30 (permalink) Old 05-28-2009, 08:51 AM
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Mine had a 160 when I got it. It overheated. Put in a 180, no more problems......and it runs better.

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post #14 of 30 (permalink) Old 05-28-2009, 08:55 AM
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Before you change the thermostat, take the time to do a flush treatment. It might remove some scale / crud from the coolant system. You will be draining the system and changing the antifreeze (you live in NJ so antifreeze is a given) to do the replacement as it is. Highly recommended is to add a bottle of Redline Water Wetter with the new antifreeze mix. As noted in above posts, 180 deg t-stat is about as low as you should ever require.

If you continue to have temp creep, you'll have to start looking at other items (radiator condition, water pump impeller condition, etc).

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post #15 of 30 (permalink) Old 05-28-2009, 09:02 AM
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Re: benefits of 160 deg. vs. 180 deg. thermostat

Thermostats aren't cooling devices - they're heating devices. That is, they make sure your engine stays at a MINIMUM temperature, not maximum. They keep the coolant from circulating to the radiator until the engine has warmed up enough, and then maintains that minimum temperature.

Lower thermostats don't solve overheating problems! Hotrodders use them because they reduce the heat under the intake manifold and therefore get a slightly denser intake charge. But, running your engine cooler increases wear and decreases efficiency, so that denser charge comes at quite a price.

Overheating problems are caused by several things:
1) Inadequate or clogged-up radiators,
2) Inadequate fan
3) Lack of fan shroud
4) Gunked-up block restricting heat transfer
5) Contaminated coolant
6) Inadequate water pump.

If you're having overheating problems, tackle these things, first. A lower temp thermostat won't make the car run any cooler - just warm up more slowly.

As for the thermostat, run AT LEAST a 180. A 195 will work nicely, too. Some run a 180 in the summer and 195 in the winter (for better heater performance), but I'm not sure there's validity to even that approach. Pick one and run it year 'round.

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