[Tbohann]

Curious what is normal operating water temp for a 302, flat tappet cam, no ac, 4bbl at 50/50 coolant mix. Standard 4 blade fan setup with shroud. Running 180 degree thermostat. I’m curious when is open where is normal operating temp. Car is 1967 convertible

 

[Travis98146]

Your thermostat should open somewhere around 180-190 degrees. Your operating temp will run from 180 up to 200-215, depending on type of travel and outside temps. You might see the higher temps at idle after a highway run and the lower temps while driving.

 

[Tbohann]

Thanks Travis. Yeah I see the thermostat open at about 178 according to infrared gun. I'm chasing a symptom where gauge reads in the lower end of display then to middle of scale but definitely seems to hunt. Every now and again the gauge will quickly spike to max then immediately begin to come back down to middle of scale. After 30 minutes of idle I see the temp get to 210 degrees on the infrared gun and will pretty much stay there over a period of an additional 10 minutes or so and this is what prompted my question about normal operating temp after thermostat is open and engine is fully warm. By the way I'm in Indiana. Right now while I'm working on this it is 90 degrees each day with high humidity. I've changed thermostat with no change to symptom. Today I changed the sending unit but haven't tested it yet.

 

[zray]

now would be a great time to go on amazon.com and order yourself a Ford published shop manual.

there is no good reason to run a 180 or 160 degree thermostat. The stock thermostat is the 190/192/195 type. They came from factory by the millions with the 190-195 installed and ran great and did not overheat.

The stock thermostat does not even FULLY open until it gets to 212. Any temp between 190 and 220 is fine and will never hurt your engine. the oil needs to be over 212 to vaporize condensation. The 190- 195 thermostats lets the engine and the oil heat up as fast as possible.


PS FYI, All this is in the manual, which was written by the most knowledgable people, the same ones who designed your car. They are (or were) way smarter than me, or anyone else on internet.

PPS an IR gun is NOT an accurate way to be checking engine coolant temperature. A quality AutoMeter or other reputable brand of temp gauge is the only way to reliably know your engine temp. I prefer a full sweep mechanical gauge, but a 90 degree sweep electric gauge is better than nothing

Z.

 

[GT'sGT]

PS FYI, All this is in the manual, which was written by the most knowledgable people, the same ones who designed your car. They are (or were) way smarter than me, or anyone else on internet.


Z.

Little known fact:
The manual was not written by the same people that designed the car at all. The car was designed by engineers and the manual was written by technical writers, not the engineers. They are not any smarter, just more knowledgeable about one particular thing. I doubt they have super high IQ's or anything like that though, just normal guys doing a job.

 

[zray]

Little known fact:
The manual was not written by the same people that designed the car at all. The car was designed by engineers and the manual was written by technical writers, not the engineers. They are not any smarter, just more knowledgeable about one particular thing. I doubt they have super high IQ's or anything like that though, just normal guys doing a job.

From what my source tells me, (a retired engineer from product development ), we are both right, the shop and assembly :nerd:manuals are a collaboration between the tech writers and the engineering staff The various specifications are supplied to the writers, and they write the copy and take the photos . There was a continual back and forth vetting of the tech writers progress by the engineering dept. until the job was done.

I'd imagine the modern process is much more streamlined these days.

But with the 1960's era product, they are Overall, a pretty good job. I've only found a couple of places where the copy does not jibe with the illustrations

Z

 

[Tbohann]

zray ...yep, have the manual but maybe I just read past the answer to my question. InfraRed gun is what I have at the moment so maybe I'll be able to get better diagnostic tool soon....regarding who wrote the manual, probably a fun discussion but not answer to the question 'what is considered a normal operating range for a 302?' (Topic of this thread). Thanks for taking a couple minutes to post.

 

[Ivy66GT]

Its like most other things in life, you get what you pay for. I would agree that if you are using a $20 IR temp gun from Harbor Freight that it won't necessarily be accurate. If, however, you use a professional $300 one from a better source I would trust its numbers more than any gauge with a $10-20 sender installed in your block.

If I want to know the REAL temperature I use my IR gun. Its accurate, instant reading and I know exactly what 3/4" diameter spot its measuring. Both the accuracy and spot size vary with how expensive a gun you are using.

The symptons described by Tom sound more like a gauge problem than an engine temperature problem. Is pretty obvious he is not using a factory gauge since those are so slow acting (intentionally) that the quick changes he describes could never happen.

 

[zray]

. Any temp between 190 and 220 is fine and will never hurt your engine. the oil needs to be over 212 to vaporize condensation. The 190- 195 thermostats lets the engine and the oil heat up as fast as possible. ......"

Z.

zray ...yep, have the manual but maybe I just read past the answer to my question. InfraRed gun is what I have at the moment so maybe I'll be able to get better diagnostic tool soon....regarding who wrote the manual, probably a fun discussion but not answer to the question 'what is considered a normal operating range for a 302?' (Topic of this thread). Thanks for taking a couple minutes to post.

The answer to your question is in my post quoted above (post #4), minimum temp 190 maximum continuous temp 220. Very brief temp of 225 F , like in traffic or at stop lights , won't hurt anything

also you can find the spec. For the stock thermostat in the back of the cooling system section of the Ford shop manual.

Since your question has already been answered a couple of times, I didn't think it going OT and rogue to mention the shop manuals as an aside. Sorry if that was offensive.

Re using an IR gun, IMHO, they are a very ineffective way of measuring the coolant temp. The surface of hose or metal you point at is not the same as a quality temperature probe reading immersed in the coolant. Plus, what you want is a temp reading WHILE YOU ARE DRIVING and with the engine UNDER A LOAD.. a quality aftermarket gauge, such as the autometer mechanical temp gauge, is the only way to get consistent reading .

https://www.summitracing.com/parts/atm-2432

A full sweep gauge will give you the most usable information. In a mechanical version, the full sweep gauge is not expensive. Reasonably priced electric gauges are usually 90-120 degree sweep, and therefore not as easy to read precisely. . Full seeep electric gauges are available, but usually cost double the price of the full sweep mechical gauge.

pulling the car over and doing an IR reading with the engine under NO LOAD doesn't tell you much in the way of relevant information, again, just my opinion, based on 50+ years experience. Of course the makers of the IR gums are very happy you are buying their product....

Z

 

[Urambo Tauro]

Another thing is that the pyrometer gun only measures the surface, which is subject to some small degree of ambient cooling. The reading will be close, though. The tricky part about using them is that you really need to hold the gun as close to the surface as possible, or else nearby components in its field of vision will affect the reading.

 

[Tbohann]

No zray...you misunderstood my response or I didn't word it well. I was just trying to show that I do try to do some homework before I pop a question on here. I did not see the comment about operating range in your post...see it now...it's exactly what I was looking for...thanks. I just was chuckling about the 'who wrote the book' tangent because I see that on Facebook all the time where a thread begins on one topic and evolves into something completely different by the end of the thread. Thanks again!

 

[Tbohann]

Yeah I am thinking it may be the gauge. With new thermostat and sending unit installed symptom still there (but gauge does react much smoother with new sending unit). The temperature sending unit range runs from 197 ohms cold to 14 ohms at 220 degrees F. I am thinking at operating temperature the low resistance occasionally show up as an 'open' causing gauge to spike to 'high' then return to midpoint. All other gauges working fine so I guess I am thinking the IVR is fine. Although my infrared gun is lower end quality, it stills returns 205 to 210 after driving for 45 minutes and then idling. Reading is 1 inch from manifold side of thermostat and other is 1 inch from manifold at water temperature sending unit.

 

[GT'sGT]

From what my source tells me, (a retired engineer from product development ), we are both right, the shop and assembly :nerd:manuals are a collaboration between the tech writers and the engineering staff The various specifications are supplied to the writers, and they write the copy and take the photos . There was a continual back and forth vetting of the tech writers progress by the engineering dept. until the job was done.

I'd imagine the modern process is much more streamlined these days.

But with the 1960's era product, they are Overall, a pretty good job. I've only found a couple of places where the copy does not jibe with the illustrations

Z

Nope. The engineers never write anything, that's the job of the technical writer, trust me, I did that job before becoming a technician. A lot of the information comes from the engineering team, generally the head of the department but the engineers do not write manuals <Period>
Sorry to burst your bubble. That's just how it is though. I know a lot of people believe that engineers and designers write manuals though, it's a common mistake.

 

[Charles Reeves]

Depends on where you work, GT'sGT. I was an engineer, and I wrote manuals. The technical writers/editors cleaned them up.

 

[poqman]

also you can find the spec. For the stock thermostat in the back of the cooling system section of the Ford shop manual.

Looking at the 1966 Mustang Shop manual cooling system specifications, I cannot find that a specific thermostat is specified for the 289. Instead the manual gives two choices.
Choice 1: "low temperature", opens 155-162, fully opens 182.
Choice 2: "high temperature", opens 188-195, fully opens 210-212.
It would seem that either the 180 or the 190 thermostats can be used and meet the shop manual specification. I don't see where a 180 thermostat is wrong or the 190 is right. It would seem that a 180 for the summer and a 190 for the winter would work fine. In my climate, I can use a 180 year round.

 

[Ivy66GT]

The tricky part about using them is that you really need to hold the gun as close to the surface as possible, or else nearby components in its field of vision will affect the reading.

That is true for the cheap ones with low FOV ratio. However, a better gun like I use has a 50:1 ratio which means it is only sensitive in a 3/4" diameter spot at any range up to almost 6 feet. (The lens is 3/4" and the 'focus' spot is about 3' from the gun.) A cheap HF gun with a 5:1 ratio has a huge spot size since it has no focusing optics. IR optics are expensive. I know, I designed and used them for 35 years.

Almost all these cars came with a 192 F thermostat. There were still owners who would change t-stats for winter/summer. With ethylene glycol antifreeze in the new Mustang that was/is not necessary and you can use 192 F year round which is the best for your engine. Changing to a lower t-stat in the dark ages was only to lower the temp so the alcohol some used for antifreeze didn't boil out of the system. It wasn't good for the engine, only for the alcohol in the radiator. It was little things like that limited engine lifetimes; your grandfather would have been excited to get 50k miles before an engine overhaul. If you don't get 250K miles on a new car today there is something wrong.

 

[Tbohann]

Morning guys...just a follow-up on this problem. I have installed new (and tested) 180F thermostat and new (and tested) temp sending unit. Put a shroud on it as well. Problem still there where, after 20 minutes or so, the temp gauge will read in the upper 2/3 of the range on warm side. Then the gauge will just quickly(and somewhat randomly) move to full hot then come back down to the middle or the upper 2/3 portion again. I have burped the motor with front end jacked up many times now. The following are the results of troubleshooting so far:
- No white smoke from exhaust
- No apparent oil in coolant
- With a thermocouple snaked into the radiator all the way to the top hose, temp reading is steady at 204-206 deg F during the whole time.
- With an ohmmeter on the sending unit, reading steady 22.0 to 22.5 ohms (based on testing with double boiler equates to roughly 208 deg F) during the whole time
- Grounding the lead to temp gauge, the gauge will read maximum
- Using a series of 2-watt resistors, testing of the gauge appears very accurate.
- IVR not yet tested but seeing no issues with gas gauge or oil pressure gauge
- been looking for any potential shorts in the wiring (maybe only caused by vibration or heat?)

This has been fun to work through but would definitely welcome additional input. My next step is to take another IVR and temp gauge and feed the signal from the sending unit while the engine is running to this setup to see if the problem shows up with different IVR and gauge.

Thanks again for any thoughts,

Tom

 

[FordSparkee]

Little known fact:
The manual was not written by the same people that designed the car at all. The car was designed by engineers and the manual was written by technical writers, not the engineers. They are not any smarter, just more knowledgeable about one particular thing. I doubt they have super high IQ's or anything like that though, just normal guys doing a job.

Donkey! I think its obvious he wasnt implying they were savants or anything like that. Just far better informed in the matter. Double DONKEY!

 

[Grimbrand]

LOL! Well, this may be an old post, but welcome to AFM anyway, Sparkee! =)