All Small Six Thermostat Temp for the 3.3 / 200cid in line 6

[1981 Capri]

I have the in line 200 in a Fox body . I will be changing the coolant . Would like to renew the thermostat at that time . I have lost track of when the thermostat was changed last or what temp is in the engine now . The engine bay seems to me to be too hot ,and the hood is hot . The car has a new rad . The car does not have hood vents , just fake looking hood vents . Engine has the log head with a single barrel carb . i am wondering if this is over heating this little carb . The car has been repainted so do not want to over heat the hood paint . I lift the hood when i get home to let the heat out . what is the lowest thermostat temp i could go to ? 180 ? or 160 ? thanks for your time and input .

 

[B RON CO]

Hi, I use a 180* Motorcraft thermostat in my Bronco. The temp gauge rarely reaches 200*. The Motorcraft thermostat is very good quality. Good luck.

 

[1981 Capri]

B RON CO thanks for the input . My car is a 1981 not sure if that makes any difference , could I please have a part number for the 180 F Motorcraft thermostat .

 

[65coupei6]

For this kind of stuff I use rockauto for cross reference.

1981 MERCURY CAPRI 3.3L 200cid L6 Thermostat | RockAuto

RockAuto ships auto parts and body parts from over 300 manufacturers to customers' doors worldwide, all at warehouse prices. Easy to use parts catalog.

www.rockauto.com

 

[DON]

I have the in line 200 in a Fox body . I will be changing the coolant . Would like to renew the thermostat at that time . I have lost track of when the thermostat was changed last or what temp is in the engine now . The engine bay seems to me to be too hot ,and the hood is hot . The car has a new rad . The car does not have hood vents , just fake looking hood vents . Engine has the log head with a single barrel carb . i am wondering if this is over heating this little carb . The car has been repainted so do not want to over heat the hood paint . I lift the hood when i get home to let the heat out . what is the lowest thermostat temp i could go to ? 180 ? or 160 ? thanks for your time and input .

180 should be good, if you live in cold country the heater might not get real warm, I live in central Fla. I have a 390 in a 67 mustang that puts out a lot more heat than the 200, I too open the hood when I get home, but have never had a problem with hood paint, but better safe than sorry!

 

[DON]

Hood insulation might be an option for you

 

[1981 Capri]

We do not drive this Fox body in cold weather or even wet weather . It's rare that we even use this car . We have an 82 Oldsmobile to drive in colder temperatures. So a 160 thermostat would be enough heater core heat for us . But from what i read the 160 F will cause issues. Painting a car is now expensive , so i lift the hood as a preventative measure . Don I agree i could add Hood insulation as another preventative measure. But at this next coolant change will start with a thermostat change .

 

[DON]

The other thing to remember, a lot of under hood heat is from the exhaust. 10 or even 20 degrees difference in thermostat rating isn’t going to change that. I haven’t installed them yet but I sent my header’s to Jet Hot. Their coatings are supposed to help control exhaust heat….we will see

 

[Frank]

We do not drive this Fox body in cold weather or even wet weather . It's rare that we even use this car . We have an 82 Oldsmobile to drive in colder temperatures. So a 160 thermostat would be enough heater core heat for us . But from what i read the 160 F will cause issues. Painting a car is now expensive , so i lift the hood as a preventative measure . Don I agree i could add Hood insulation as another preventative measure. But at this next coolant change will start with a thermostat change .

A 160* would work fine. The "issue" is the oil may run too cool to fully evaporate all blow by moisture. Keeping a closer eye on oil condition and potentially a more frequent oil change is not an excessive price to pay on an occasional-use specialty vehicle. Don't have a 160* in service right now, but have had on several occasions. I like the cooler "everything" under the hood- there's nothing wrong with using a 160* IMO

 

[1981 Capri]

Frank we keep a close watch on the engine oil colour and smell . how often should we change it if we only put on about 300 miles a year ? and if i change to a 160 how often should the oil be changed ?

Don good point about the exhaust , The engine had blown an exhaust gasket , could that have been from excess engine heat ? or just age ? 1981 ! so had the exhaust manifold off to replace the gasket , the manifold on the car has the attached cat built onto it , the cat had nothing in it , so where did that go ! maybe stuck in the muffler ? i think that was a mistake to put that same cat exhaust manifold back on, but thats another thread topic ! even with the cat empty still seems like a lot of heat under the hood , but i do not have a gauge on the engine to prove that .

 

[TrickSix]

If the catalytic converter guts did blow through and partially clog up your muffler, that could make your exhaust system run hotter. Even if a prior owner had removed the cat guts, just the relatively large surface area of that hot canister radiating heat may be making the situation worse. A regular exhaust manifold should fit, but you will need to add a short piece of pipe to reach and splice onto the old exhaust pipe after the cat.

 

[DON]

Hard to tell, especially without being there, what caused the exhaust failure. Someone might have knocked out the guts of the cat. Change the oil at least once a year. If it starts to get real black before then, change it. I have gotten in the habit of writing the date on the oil filter with a sharpie…the date it was changed. That way no confusion on when it needs to be changed again. For black filters and parts, the silver sharpie works great

 

[PSIG]

But from what i read the 160 F will cause issues.

It did in the old days in short-trip cars (limited warm-up), and gave less heat and slower defrosting in dead winter. The factory recommended 3000-mile oil changes, or annual. If you didn't change the oil for 15000 miles the oil would begin to sludge. While that's not a problem with today's oils (since SJ I think it was), it's still good maintenance to stick with 3000-miles or annual. I forget which year they stopped for emissions regulation reasons, but the 160° was an officially approved alternate thermostat for the 3.3L in the service manuals.

Now my opinion - I run 160° in everything classic. Never any issues, though rarely in sub-freezing weather. Power is a bit better, and emissions are... 1960s. Well, actually better as I keep them tuned well. No sludge, no milky, no nothing. Cooler also helps as modern pump gas additives are prone to carb percolation and lower boiling point, with all kinds of problems. Never had those issues either. IMO, 160 is fine for mild weather.

 

[Frank]

Frank we keep a close watch on the engine oil colour and smell . how often should we change it if we only put on about 300 miles a year ? and if i change to a 160 how often should the oil be changed ?

Don good point about the exhaust , The engine had blown an exhaust gasket , could that have been from excess engine heat ? or just age ? 1981 ! so had the exhaust manifold off to replace the gasket , the manifold on the car has the attached cat built onto it , the cat had nothing in it , so where did that go ! maybe stuck in the muffler ? i think that was a mistake to put that same cat exhaust manifold back on, but thats another thread topic ! even with the cat empty still seems like a lot of heat under the hood , but i do not have a gauge on the engine to prove that .

As stated, change the oil and filter once a year. With anything less than 1500 or so miles/year, the 160* Tstat will not have a detrimental effect.

The exhaust gasket blowing out, excessive underhood heat and the cat missing it's internals may be connected, if the muffler is full of cat material and causing backpressure.
Stand at the tail pipe and have someone race the engine a few times. Listen carefully. If it's hissy, too quiet or not blasting a good stream volume then there's a restriction. Whoever's operating the accelerator pedal needs to "romp" it briefly. The goal is not high rpms as much as high volume, which requires a heavy, brief pedal application. This listening method works even better if there's somewhere you can ride alongside the rear of the car with the window down and have them accelerate hard under load. If it sounds like an air compressor the muffler needs to be replaced.
Many places sell an exhaust wrap. It's kind of a pain to install, but wrapping the hollow cat and nearby pipes will reduce engine bay heat.

 

[drag-200stang]

Oddly my high school 200 full carb bore sized tri-power ran faster at the track when run at 180, colder would run slower times. Probably because of open long tube headers, I think it would run richer because of the stronger suck signal to the carbs and needed the heat for better combustion.. The head also had a port divider that insulates some of the exhaust heat from the intake.

 

[1981 Capri]

PSIG good point about the fuel , i should have mentioned that in my very first post , it is very difficult in my area to find no Ethanol fuel . So how does Ethanol fuel effect thermostat temp choices ? Good to know that the 160 is listed in the 3.3 service manuals .

Tricksix my wife is the original owner has every service record . i do not see anything in service records that mentions gutting the cat . Unless it was not legal at the time to gut the cat , so the shop did not want that in writing on a bill ?

Frank what about taking the car to a shop and have the muffler removed to have a look see inside . would a shop be able to see anything wrong ?

Don good idea about keeping track of filter age , we do not do our own work , so have a paper trail of service records . Keep all oil change records in a 3 ring binder.

we do not do our own work , was a mistake on my part to have a shop just change the exhaust manifold gasket should have put on an after market exhaust manifold . buts that another thread topic !

 

[63 Sprint]

It did in the old days in short-trip cars (limited warm-up), and gave less heat and slower defrosting in dead winter. The factory recommended 3000-mile oil changes, or annual. If you didn't change the oil for 15000 miles the oil would begin to sludge. While that's not a problem with today's oils (since SJ I think it was), it's still good maintenance to stick with 3000-miles or annual. I forget which year they stopped for emissions regulation reasons, but the 160° was an officially approved alternate thermostat for the 3.3L in the service manuals.

Now my opinion - I run 160° in everything classic. Never any issues, though rarely in sub-freezing weather. Power is a bit better, and emissions are... 1960s. Well, actually better as I keep them tuned well. No sludge, no milky, no nothing. Cooler also helps as modern pump gas additives are prone to carb percolation and lower boiling point, with all kinds of problems. Never had those issues either. IMO, 160 is fine for mild weather.

The vaporization point of ethanol and gas are totally different. You need more heat than 160 degrees F in order for both the ethanol and gasoline to vaporize properly.

This was experienced when the thermostat went bad on the 300. Poor fuel economy and performance was the end result.

Today’s fuels are not the same as fuels were back when the Ford manuals were written in the 1960’s. Today’s fuels takes much more HEAT to vaporize properly.

Since the intake manifold is part of the small block cylinder head, the intake manifold will be cooled by the engine coolant. It’s best to use a higher temperature thermostat that will aid in keeping the manifold above the vaporization point of ethanol by a decent margin to be sure that ethanol is vaporized.

 

[Frank]

i do not see anything in service records that mentions gutting the cat . Unless it was not legal at the time to gut the cat , so the shop did not want that in writing on a bill ?

Frank what about taking the car to a shop and have the muffler removed to have a look see inside . would a shop be able to see anything wrong ?

Yes a shop would know once the muffler is removed. Since there's no reason for or record of cat modifications, I recommend the muffler be removed and checked. Replacement mufflers are not expensive, if that one is suspect. Exhaust restriction will cause higher underhood temps, which is your original concern. You may ask them the cost of removing the cat and replacing the section with pipe, if it's a place you trust.

 

[DON]

Interesting, please expound on the vaporization of gas/ ethonal, I remember that carbs atomized fuel ( same with injectors ). Engines aren’t designed to run on vapor

 

[Frank]

Interesting, please expound on the vaporization of gas/ ethonal, I remember that carbs atomized fuel ( same with injectors ). Engines aren’t designed to run on vapor

It takes more energy (heat) to vaporize alcohol, bottom line. with a stock log intake/exhaust there's plenty of intake heat on the OP's engine to vaporize fine with a cooler t'stat IMO. The aftermarket intakes without direct exhaust heat need more help.