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Is my car overheating? I'm getting crazy!

3K views 28 replies 7 participants last post by  ufobobo 
#1 ·
These are some temperatures I got today with my infrared thermometer pointed around the engine. To: intake manifold, thermostat housing, upper radiator hose, down radiator hose and radiator inlet.

Consider that my temperature gauge indicator is on the H mark when I get these temperatures.

Is the sending unit faulty or my car is really overheating?

Put a new 3 rows aluminum radiator, fan shroud, flex fan and a new 180 thermostat.


I'm getting crazy!
 

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#2 ·
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Assuming your infra red gun is accurate, your gauge is reading incorrectly. The most common cause for that is a sender that is inaccurate which most senders are even though they are claimed to be for your particular car. One thing you can do is to put a thin piece of tape on the gauge when your gun reads 180 on the intake manifold just behind the thermostat housing and another when it is at maybe 200. This will give you a reference point on the gauge for now.

When working properly, your temp should not go more than around 7 degrees above what the thermostat rating is. At 209, your 20 above your thermostat so this means that your cooling system is not working properly. This is typically because the fan is not pulling enough air when this condition occurs at idle like yours is. If the temperature goes down to 180 to 187 while you are doing around 40 mph or more, it means that your radiator is big enough. If the temp does not go down at that speed, it means the radiator is too small or the lower radiator hose ma be getting sucked closed. It should have a spring in it. Grab the lower radiator hose and try to compress it. If it compresses, it does not have a spring.
 
#8 ·
what brand of 6 blade is it?

how long has it been doing this?

the flex a lite metal fan 1717p is one of the better ones but from the sound of it, it won't cure your problem either.

if further checking, confirms it is running that hot, i might check the water pump. if thats ok, i would try a 16" spal fan. they come in both push and pull models.

https://webstore.spalusa.com/content/files/content/PDF/30102113_SPEC.pdf


the are $140.00 . . if you get one, make sure you get the correct suction or blow type.

JayCorp Technologies - SPAL 16" High Performance Curved Blade Fan

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#7 ·
I agree that your temp sender is inaccurate. With the factory 192F thermostat for a 289, full open did not occur until 212F. You are not overheating, your gauge is wrong. For the temps you measure the gauge needle should be ever so slightly to the right of straight up.

Shiny objects don't give an accurate temp reading. The temp reading is also from a circle much, much larger than the laser spot and, at that close of a range, probably not even centered on the laser spot. That explains the extra-low 120F since you are measuring mostly the shiny hose clamp and radiator and not the hose. Even the 177F on the hose is probably a little low since the spot being measured is larger than the hose diameter.
 
#9 ·
Your temp gauge should be right in the middle when it's reading 180. So if the temp there on the intake manifold near the sending unit is 209 then your gauge & sender are accurate. I fought mine for 2 years before I replaced my 185 thermostat & original style radiator with a 165 thermostat & aluminum radiator. I also have an electric "pusher" fan I have mounted up under the hood latch brace and I set it up to come on at 200 degrees. However after the radiator & thermostat change it has NOT come on!

This is me on July 4th idling along a parade route (probably ~25-30 minutes of idling). Sorry the pic is a little fuzzy wasn't easy to hold camera with one hand while steering with my knee & tossing candy out the window with my other hand.

 
#11 ·
Your temp gauge should be right in the middle when it's reading 180. So if the temp there on the intake manifold near the sending unit is 209 then your gauge & sender are accurate. I fought mine for 2 years before I replaced my 185 thermostat & original style radiator with a 165 thermostat & aluminum radiator. I also have an electric "pusher" fan I have mounted up under the hood latch brace and I set it up to come on at 200 degrees. However after the radiator & thermostat change it has NOT come on!

This is me on July 4th idling along a parade route (probably ~25-30 minutes of idling). Sorry the pic is a little fuzzy wasn't easy to hold camera with one hand while steering with my knee & tossing candy out the window with my other hand.
Hi Cracker,

how can the sender be accurate if 209 is the real temperature near the sending unit?
The needle at these temperatures is almost on the H mark and that should be considered the overheating point (230 - 250F), right?

Also, reading the forums I always found different opinions about dangerous temperature for the engine, what do you consider really dangerous? Someone says 230 some others 250/260
 
#12 ·
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every time i check an engine temp with an infra red gun, i shoot it right behind the thermostat housing and it is always within a few degrees of a real temp gauge, therefore, the cast iron or painted surface should not cause your temp gauge to read artificially high.

a very simple test to confirm the actual water temp if you want to is to take the rad cap off and put a candy thermometer in the rad hole . . this temp may be a bit lower than the temp in the block at the thermostat.

you can also check the temp of the bottom of the radiator hose when your block reads 209 degrees and you may find that it is slightly hotter than the top of the hose because the hose may only be around 1/3rd to 1/2 full at idle when your thermostat is open. if it is hotter, it still doesn't mean it is accurate but you can shoot the bottom of the rubber hose to compare the two if you want.

you can also shoot the front of the rad just below the inlet fitting where the water is certain to be and see what it says.

you have a 180 thermostat . if your temp is really 209, your cooling system is obviously not working properly. the engine is not overheating at 209 as was mentioned and it can safely go a little higher but i would correct the problem if it does not run near thermostat temp all the time.
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#14 ·
The Ford temp gauge was designed so that the 192F thermostat would put the needle at center scale. The far right 'H' mark was the boiling point of the antifreeze solution used: 250F. Some of the older Ford senders had either 250 or 260 stamped on them indicating what temp an 'H' would represent.

http://www.allfordmustangs.com/forums/classic-tech/204666-temperature-senders.html

I agree that the best spot for IR temp measurements is the back side of the thermostat housing. The paint there gives a good reading and its a big enough hot spot that most guns will not have a problem. Anything shiny is not a good place to measure since shiny surfaces don't emit much IR energy. A black hose is a good material for IR measurements but only if your IR gun has a small field of view. Most cheap ones have a LARGE field of view and will average the hose along with a bunch of other cooler stuff and give you a low reading.

The engine was designed to run at 200F and 210F or even a little higher when idling is not any problem as long as it cools back down with more air flow on the highway. No matter what thermostat you use its the radiator that determines how cool your engine can run. Once a 180 stat is wide open it has no control over temperature; the air flow through your radiator will determine the coolant temp. Using a 160 isn't recommended since engine wear is 10x worse at 160 then 180. When alcohol was used as an antifreeze (in the 1950s) anything over 160 would boil out the antifreeze. Otherwise, there was never any reason to use a 160 stat.
 
#15 ·
Hello Cracker289, Can you tell me why you chose to put your fan in the front? Are you still running your stock fan also? Is your aluminum radiator the stock size or did you go with a bigger one? I have a newly built engine and it's getting hot when idling. It seems you did all the right things to your mustang. Any advise is greatly appreciated. Thanks George
 
#16 ·
Hi George, I like the stock look, so I wanted to keep the original style engine fan, but it would always get too hot when idling in traffic, so I got to looking and saw that I could fit a pusher fan in front that is really not too noticeable. I mean if you look for it you'll see it but if you just walk up to check out the engine it's not something you'll notice because its up under the hood latch brace. I wired it up with a 30 amp relay connected to a temp switch in the thermostat housing, and it used to do a pretty good job of keeping it from getting too hot at idle but like I said now that I changed my radiator and thermostat it hasn't even gotten hot enough to kick on. I used an aluminum radiator that fit in the stock location, my water pump is a parts store replacement, and my thermostat is 165. Engine fan has a parts store replacement fan clutch and I believe 16 or 17 inch fan with 6 blades. In 2014 during the same parade I started overheating and had to pull off a side road and have a cop move the barricade to let me get away from the parade and out on the road to cool it down some. This year, never even got to the halfway point!
 
#19 ·
That's about where mine was too. Sometimes on the highway it would creep up hotter than that and I would need to slow down and let it work it's way back down to the halfway point.

Do you have any of the other symptoms of being too hot, like "pinging" when you press the gas pedal down, or very hard to restart if you stop off at the gas station for a few minutes, etc?
 
#18 ·
Your sender needs replacing. You can get them for as little as $4.

The first photo shows the needle to the right of center about where it should be for the 209F IR readings you showed earlier. The second photo shows what you should be seeing with maybe 230F and you are NOT that hot. If you were there would be coolant coming out of the overflow tube every time you drive the car.
 
#21 ·
Hi Cracker, thank you for your help.

When the car is idling hot (needle at H mark) I can hear a ping. It is not loud at all, you can pay attention to it only if you know the engine (like me). No ping when i press the gas pedal down.

I don't have any hard restart, even if I stop for few minutes at the gas station. The only thing I have to do is to push just a little bit the throttle pedal down.
 
#24 ·
Ivy is spot on if it never exceeds 210-215 change the sender and keep going, you are thinking too hard about this. Iron will heat soak and with coolant temps coming out of the block at 200* tstat full open this is not uncommon at all, nor are temps 10-15* higher than tsat ratings.
Jarbergers is also right about airflow, the fan is most Inefficent at Drive in traffic. For that reason I have gone to Electric fans with controllers. Techkology is a good thing my friend, max airflow when needed(700rpm in gear with or without ac) and they do not even run when you exceed 25-35 mph. You would be surprised if you took your fan off and drove above 40 mph the temp will be exactly as if the fan were in place...sounds crazy but i did it to prove to it myself.
 
#28 ·
You never know what you might get. The new one could be better or worse than your present one. So that you know what it is, put it in a pan of water on the kitchen stove and measure its resistance vs temperature as you slowly heat it up to boiling. If you want to go higher than 212F you need to use cooking oil instead of water. Center scale on your gauge should be whatever temp you have when the sender resistance measures ~25 Ohms. The right end of the scale will be at 10 Ohms.

For that matter, do the same for your present sender to see how they compare.

Without that kind of a measurement you will always be guessing as to what is happening with your gauge.
 
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