Running too hot.

[taank]

68 c10 518 hp 383 stroker. High flow 165 jegs stat. Original or original replacement v8 radiator. Serpentine drive standard flow water pump.

On warm days. 80 or so the truck will run 200 to 215 on the highway or in town. Dual electric fans with shroud. Fans run constant. If I'm just driving around town. Truck stays 160 to 190. As soon as I get on the highway it will get hot. I'm thinking the radiator may not be efficient enough. Any thoughts?
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[taank]

I have a new direct fit 4 core radiator on order. But I would still like to try and trouble shoot this.
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[BIGKEV]

Through a 180 stat in it, there is a good chance the coolant isn't staying in the radiator long enough to actually cool. Also what are the ratings on your fans?

[68gmsee]

Radiator may help, but a quick check list if you haven't done them already;

Test the thermostat in pot of water with thermometer to insure it's opening.
Make sure the temp is correct on the temp gauge. They can be inaccurate.
Check for collapsing lower radiator hose when accelerating. (rev the engine while observing the hose)
Replace the thermostat with higher rating. (180-185?)
Replace the cap.
Install an overflow container.
Do a leak down test on radiator.
Cylinder leak down test on the engine to check for head gasket failure.

[geezer#99]

Easier way to check your bottom rad hose is to squeeze it when it's cold. If there's a coil in it you'll feel it. If no coil. Easy to make your own.

[Fitz]

Originally Posted by taank

68 c10 518 hp 383 stroker. High flow 165 jegs stat. Original or original replacement v8 radiator. Serpentine drive standard flow water pump.

On warm days. 80 or so the truck will run 200 to 215 on the highway or in town. Dual electric fans with shroud. Fans run constant. If I'm just driving around town. Truck stays 160 to 190. As soon as I get on the highway it will get hot. I'm thinking the radiator may not be efficient enough. Any thoughts?
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Lower is not necessarily better when it comes to thermostat temps but if you really are making that much HP I doubt you have enough radiator to cool it. The OEM rad is a two row unit and I think you will need a four row Rad. The difference between Radiator inlet and outlet temps will tell the story. I measure this with a thermocouple taped onto the inlet and outlet neck of the rad and read them with a microvolt meter. There are ways of connecting ordinary senders for temp guages but that's a bit messy if you're just trying to satisfy your curiousity.

[dougminton]

I'm not positive but shouldn't a serpentine setup have a reverse rotation water pump.

[mrein3]

How does that old rule of thumb go?
If it overheats in the driveway it is the fan.
If it overheats on the highway it is the radiator.

I too have a 383. I can't remember if the 4-row radiator came before or after the 383 but I've never had an issue with the stock fan and 4-row radiator.

Since you have a new radiator coming anyways, I'd swap it in and see if your problem goes away. With that eliminated from the equation, it will be much easier to diagnose if the problem still exists.

[vasquezmrysvll]

what serp. system are you useing? if its stock gm, you MUST use a reverse rotation pump. not to be confused with "reverse flow"

[taank]

Originally Posted by vasquezmrysvll

what serp. system are you useing? if its stock gm, you MUST use a reverse rotation pump. not to be confused with "reverse flow"

It's the same pump that came with the serp belt kit from gm.
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[steelhorse]

A stock style radiator was never ment to cool a 500+hp engine.I would recomend going to a high proformance radiator.On a side note on my 75 Ford I put a big block school bus radiator in when I redid the engine and it stays cool no matter what the temp is.

[Longhorn Man]

i would suspect coolant flow. Could be a bad pump, or a semi-clogged rad.

[RRR18]

Higher thermostat.

[taank]

How would a high temp stat keep the motor cooler. I guess I'm just not getting the reasoning. I have a big ass radiator coming
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[RRR18]

I know it sounds weird but it always worked for me. I lived in Tucson, AZ for 15 years and every single time me or any of my buddies tried lower than a 180 stat we were overheating. Now keep in mind these were daily drivers of every american make and model and engine combo with mostly close to stock cooling systems. I can't explain the technical side of it....someone else will....I can only tell my experience. That keeps me outta looking like a dick.

[DANTIP]

I've had excellent luck with factory 4-row radiators when they are healthy. However, Everything must be working properly in order to get good results. As mentioned, low-coolant flow due to fouled/clogged radiator, bad thermostat, collapsing suction hose, bad water pump, etc. along with bad fan-clutch on the air side all contribute to poor cooling performance. If this is not your specialty, find an expert! I bet it will be cheaper than playing parts-change roulette. Please let us know what the root cause was and what was needed to fix it.

[geezer#99]

A lower temp stat let's say 180 will be open all the time. Continuos flow. No retention time for cooling in the rad. A 195 will be closed a bit. Restricting flow enough for better retention time in the rad. Thermo will cycle.
Also it's not all about the number of cores in your rad. It's about design of your cooling tubes, the flow of coolant, what your rad is made of (aluminum) and flow through the rad.
I've seen a custom 5 core rad cool no better than a stock 3 core rad did.
A new big ass rad could be a good start. Maybe.
JMHO

[68gmsee]

Going to a higher degree won't necessarily mean it will solve your problem but it's a cheap test to try. Also, it does help warm the engine up to temp quicker and prevents wear, carbon buildup, etc.

A good explanation.

http://www.2carpros.com/articles/how...ermostat-works
.... Never run an engine without a thermostat because the thermostat works as a system flow regulator as well. What this means is the thermostat has a specific opening that regulates the flow through the cooling system. If the coolant is allowed to flow too quickly through the radiator the coolant will not have time to transfer the heat it has absorbed. This will cause the engine to overheat.

[GASoline71]

The high flow thermostat isn't helping. A drag car only doing a warm up, burnout, and a 1/4 mile run and back to the pits is what they are designed for. Huck a regular flow thermostat in there.

Gary