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Old 05-06-2013, 09:43 PM
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Running hot?

Now that I've put some miles on my build I have gotten a feel for my running temps and think they seem a little high compared to others with similar setups. Maybe you can help me with this.

I'm running a fresh built mild 350 sbc build (vortec heads, Lunati 60102) in an old pickup. I have a Northern aluminum radiator with a shrouded derale electric fan rated for like 2500cfm. I'm running a 185* thermostat I had to loop my heater core plumbing because the core crapped out. It seems my temperature always climbs right up to about 212* and stops dead. I have my temperature probe on the driver's side cast iron head between the front two block hugger ports.

The grill on the truck is pretty wide open and gets a lot of airflow. I was just hoping my temps would be closer to 190-200 tops. I'm guessing that getting the heater core in the chain may be good for a slight drop in temp, but is there anything else I can do?

My temp gauge displays like this:

100---^---175---^---250

My needle always rests dead center between 175 and 250 whether its 50 degrees out or 80 degrees. It never drops even when I'm doing 60 mph.

Should I even be concerned about this? Can I expect temps to drop once I put some miles on the engine? I just broke 100 miles on the fresh build.

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Old 05-06-2013, 09:54 PM
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Move the sender out to the intake manifold and you'll sleep a little better.
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Old 05-06-2013, 10:19 PM
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I thought that might make a difference. So does that head read hotter than the intake manifold? and what would be the more accurate reading? Is 210 normal at the head and nothing to worry about?
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Old 05-07-2013, 02:03 AM
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Quote:
Originally Posted by RatPin View Post
I thought that might make a difference. So does that head read hotter than the intake manifold? and what would be the more accurate reading? Is 210 normal at the head and nothing to worry about?
Nothing I'd be worried about. Motors need to run hotter than most fellows think anyway. I just cringe when I read about someone installing a 160 thermostat, when in actuality they should be installing a 205 thermostat.
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Old 05-07-2013, 08:40 AM
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What are you running for coolant and how many cores does your radiator have? With iron heads I wouldn't be concerned. Im always a little leery about how accurate the electric fan cfm ratings are done. Do you know what PSI your radiator cap is rated for.
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Old 05-07-2013, 09:10 AM
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Quote:
Originally Posted by RatPin View Post
Now that I've put some miles on my build I have gotten a feel for my running temps and think they seem a little high compared to others with similar setups. Maybe you can help me with this.

I'm running a fresh built mild 350 sbc build (vortec heads, Lunati 60102) in an old pickup. I have a Northern aluminum radiator with a shrouded derale electric fan rated for like 2500cfm. I'm running a 185* thermostat I had to loop my heater core plumbing because the core crapped out. It seems my temperature always climbs right up to about 212* and stops dead. I have my temperature probe on the driver's side cast iron head between the front two block hugger ports.

The grill on the truck is pretty wide open and gets a lot of airflow. I was just hoping my temps would be closer to 190-200 tops. I'm guessing that getting the heater core in the chain may be good for a slight drop in temp, but is there anything else I can do?

My temp gauge displays like this:

100---^---175---^---250

My needle always rests dead center between 175 and 250 whether its 50 degrees out or 80 degrees. It never drops even when I'm doing 60 mph.

Should I even be concerned about this? Can I expect temps to drop once I put some miles on the engine? I just broke 100 miles on the fresh build.
What is the size of the radiator core and how many rows of tubes? Is this a crossflow or conventional radiator?

Is the gauge electric or mechanical?

Frankly this sounds like a sender and/or gauge problem given the lack of sensitivity to speed or outside temp changes.

Bogie
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Old 05-07-2013, 03:55 PM
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The radiator cap I'm currently using is a 16psi. I guessed when I bought the cap. I've got a 50/50 mix of autozone green antifreeze and distilled water in the system. The radiator is a 19"x22" 2 row with 1" tube all aluminum. Part #NOR 209612. Thermo is mechanical and came from Summit and is 185*. I currently do not have an overflow tank and just have a tube out the bottom.

I'm considering buying one of those no spill radiator funnels to be absolutely certain I don't have any air left in the system.

It sounds like from what I have read that the head may read about 10* hotter than the intake. I feel a little better about that. I guess I should be more concerned of a drastic temp change while running than a slightly hot temp that stays consistent. Like I said though this engine is new and I'm still getting to know it.

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Old 05-07-2013, 08:24 PM
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Quote:
Originally Posted by techinspector1 View Post
Move the sender out to the intake manifold and you'll sleep a little better.

How much difference is found in temp readings from the block, head and intake?
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Old 05-09-2013, 04:10 AM
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Techinsp is correct in saying the sensor should be in the manifold.
This is something that I say everyday as I work in the cooling industry for vehicles.......since most sensors for temp gauges are located at the front of the manifold, near the top hose outlet.........you have to understand just exactly what the gauge is telling you.
The coolant comes out of the radiator on the bottom and starts its circulation into the motor. As is starts circulating, it is removing heat away from internal metals like heads and cylinder walls. Now it picks up more heat on its way to the top of the motor and headed to the radiator.
The coolant is now at it's hottest point as it passes the sensor, BUT you are temping coolant that is also leaving the motor.
If the fan,pump and radiator are doing there job, the temp inside the motor can be 15-20 degrees cooler but you are not gauging the coolant temp in the motor, only the temp of it leaving the motor.
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Old 05-09-2013, 10:58 AM
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Quote:
Originally Posted by sunsetdart View Post
Techinsp is correct in saying the sensor should be in the manifold.
This is something that I say everyday as I work in the cooling industry for vehicles.......since most sensors for temp gauges are located at the front of the manifold, near the top hose outlet.........you have to understand just exactly what the gauge is telling you.
The coolant comes out of the radiator on the bottom and starts its circulation into the motor. As is starts circulating, it is removing heat away from internal metals like heads and cylinder walls. Now it picks up more heat on its way to the top of the motor and headed to the radiator.
The coolant is now at it's hottest point as it passes the sensor, BUT you are temping coolant that is also leaving the motor.
If the fan,pump and radiator are doing there job, the temp inside the motor can be 15-20 degrees cooler but you are not gauging the coolant temp in the motor, only the temp of it leaving the motor.
Its not that it "should" be in the intake, its more of an illusion that makes people feel more comfortable. I have done the same thing for people who complain their temps are steady at 205-210 and feel it should be 190. Move the sender, nothing changes but a number. And they are happy.
This is what tech was referencing....not a "right or wrong"
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