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Discussion Starter #1
I've always had the issue of my 69 with a 350 running hot. In the winter I'll stick around 180 on the temp gauge but as soon as it gets warm I'm almost always running at just under 220. In the middle of the summer I rarely drive, or if I do it's at night. I'm too afraid of the car overheating. I'm not sure what thermostat is in the engine right now, but would having a 160 degree thermostat allow me to drive in the summer? I'd prefer the car stay around 180 if possible.
 

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160 will just open fully sooner than a 185....if you are hitting 220 temps either stat would be fully open so your cooling system is suffering elsewhere.

Do you have a fan shroud?
how many blades is your fan?
What condition is the radiator in? (read has it ever been flushed and do you know it is not clogged some)

Temps today are within a few degrees of what these cars were 50+ years ago and they didn't overheat in summer with properly functioning cooling systems
 

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Discussion Starter #3
160 will just open fully sooner than a 185....if you are hitting 220 temps either stat would be fully open so your cooling system is suffering elsewhere.

Do you have a fan shroud?
how many blades is your fan?
What condition is the radiator in? (read has it ever been flushed and do you know it is not clogged some)

Temps today are within a few degrees of what these cars were 50+ years ago and they didn't overheat in summer with properly functioning cooling systems
Yes i have a fan shroud, 6 blades on the fan, condition has ~8,500 miles on it but is roughly 7 years old. Not sure if it's clogged, but I've had this temp issue since originally put it and the engine in about 6 or 7 years ago.
 

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A SBC with stock shroud and fan (about 1/2 in/out of shroud) with a 185 stat should not have a problem overheating. Yeah it will run hotter in hot summer days at 200-210 in stop/go traffic but that is not a problem. Temps should drop back down to 185ish once you get mooving

You verify the temp gauge using a IR temp gun to compare?

What is your timing?

you sure you are also not running lean?
 

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Discussion Starter #6
Danny, What mods if any have been done to the engine? Running air conditioning?
Driving in stop and go traffic? Does the temp drop when moving allowing more air flow?
No mods, stock 350. I do have AC but typically drive with the top down so I rarely have it on. I typically don't have it on at all during the hotter months because I do notice the temp increases quick. Which sort of defeats the purpose of an AC.

and yes mostly stop and go traffic around town, i do not notice it drop when moving. It usually just creeps up to just under 220 and stays there during the duration of my drive.
 

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Al - Waterloo, Iowa
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220 is pretty much the top I would be comfortable with but if you're not puking.
coolant I wouldn't sweat it. Have you ever checked the accuracy of your gauge?
I use a hand held infrared thermometer to check my engine temp after a drive.
I check the upper and lower radiator hoses and the thermostat housing. Kind of
a piece of mind thing. Given the area you're in and the type of traffic you're probably
not going to improve much without throwing a lot of $$ at it. I spent the winter in Mesa
so I'm aware of the traffic.
 

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Discussion Starter #9
A SBC with stock shroud and fan (about 1/2 in/out of shroud) with a 185 stat should not have a problem overheating. Yeah it will run hotter in hot summer days at 200-210 in stop/go traffic but that is not a problem. Temps should drop back down to 185ish once you get mooving

You verify the temp gauge using a IR temp gun to compare?

What is your timing?

you sure you are also not running lean?
I have not tested it with an IR temp gun, it is possible the temp gauge is just reading incorrectly.

Not sure of my timing and if I'm running lean or not.
 

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No mods, stock 350. i do not notice it drop when moving. It usually just creeps up to just under 220 and stays there during the duration of my drive.
if temps do not drop when on hwy, steady driving, the radiator is not doing its job

..and the note offered about the clutch fan if you have one is definitely something to follow up on

Is AC condenser in front of your radiator?

You could add a electric fan in front....IMHO more a band aide but it would push more air through the radiator
 

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Discussion Starter #14
if temps do not drop when on hwy, steady driving, the radiator is not doing its job

..and the note offered about the clutch fan if you have one is definitely something to follow up on

Is AC condenser in front of your radiator?

You could add a electric fan in front....IMHO more a band aide but it would push more air through the radiator
Yes the ac condenser is in front of the radiator.

I think what I'll do is first get an IR temp gun, see what the radiator pipes read and go from there. If they do read what the gauge says then I might just go ahead and replace the radiator, clutch fan, and blade to a 7 blade fan.
 

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Al - Waterloo, Iowa
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Danny, The temp of the upper hose will be higher than the lower hose by ~25*
if the system is working correctly. The temp at the thermostat housing will be
the highest of the 3 and should be within ~10* of your cars gauge assuming
your gauge is tapped into the manifold just under the housing or in the housing.
With IR guns different materials can effect the readings. Rubber vs. steel vs. cast.
If your sender is in a cylinder head the gauge will probably read a bit higher yet.
Seems that's what most have found anyway. I basically look for the difference
between the upper and lower hoses and then verify the housing isn't higher than
my target temp of 200* max. This is just my experience.
 

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68 Camaro SS/RS clone, 454 BB 4 speed, 3.73 Posi, new paint, motor, trans and diff assembly. 2" Drop
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I will add when you get an IR Thermometer take readings at different areas all over the core, be sure the cores are clean and free from dirt/grime. If the temps vary widely that tells you some tubes may very well be clogged. I have seen crap get in there and have also seen solder particles from a poor rebuild job accumulate in tubes.
 

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Harbor freight sells cheap useful IR guns.
As suggested, do all the above. Radiators are only going to cool, by design, 20°F between inlet and outlet.
With engine off, you could feel the backside of rad core feeling for cool spots.
The AC condensor and radiator could use a good rinsing with the garden hose removing debris/bugs from the fins.
A working clutch fan will lock up at a cold start-up then release, you should hear the fan noise, then the noise will go away after about ten seconds or so.
 

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Discussion Starter #18
So this is what I've done. I borrowed a temperature gun from my father (it's made for food by the way) and after driving the car around for about 15 minutes in 90 degree heat both the upper and lower radiator hoses read about 10 degrees apart from each other, lower one being about 168 degrees and the upper being 175. At the time the temp gauge was reading just above 180, maybe 190-200. The thermostat was reading ~208 degrees. The fan was running the entire time.

So I'm not exactly sure what to take from this. It seems like the temp gauge is fairly accurate given the thermostat was around 200, and the temp gauge was in between 180 and 220. Then again I'm not sure if my temp gun was the most accurate since it's made for food, I still might try and buy a IR temp gun from somewhere, doesn't seem like Harbor Freight sells them.

I'm still leaning towards just replacing the radiator, I'm not sure if its really the issue but I feel like a newer aftermarket radiator might make a difference.
 

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Al - Waterloo, Iowa
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Danny, Your temps are very close to mine. Only real difference is I get ~20* difference
between upper and lower hoses most of the time. I would flush the radiator and change
the thermostat before replacing the radiator. It's possible your thermostat isn't opening
fully. Replacing it is cheap insurance.
 

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Discussion Starter #20
Danny, Your temps are very close to mine. Only real difference is I get ~20* difference
between upper and lower hoses most of the time. I would flush the radiator and change
the thermostat before replacing the radiator. It's possible your thermostat isn't opening
fully. Replacing it is cheap insurance.
Should i go with a 160 or 180? Or does it really matter. I'm researching the differences now.
 
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