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Mitchc said:
69NovaSS said:
normally speaking if a car can sit all day idling but over heats when driving down the road it is a coolant flow issue....and normally it is not enough flow that is causing the problem...
I agree with you.. I think the coolant is moving to fast through the system and cant cool off.. It can pickup heat but cant transfer the heat away in the radaitor.
Ummmm....I think we have a misunderstanding here because what I said was normally it is a flow issue....... NOT enough flow...which would mean you need to increase the flow through the rad not decrease the flow as your response would imply...:)
 

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71Novacaine said:
The pressure in the system also helps suck fluid into the block as well, it assists the pump and prevents cavitation.

I will argue that point with you. The pressure in the system only assists the pump if the discharge of the pump is not at the same static system pressure.
In a closed system like a auto cooling system the pump will develop the same discharge differential pressure even if the system has no pressure or if it has 15 psi on the closed system. If the pump discharge pressure indicates 50 psi with no static pressure on the closed system the pump discharge pressure would indicate 65 psi with a 15 psi static system but the suction pressure would also be positive 15 psi leaving you with the same actual 50 psi discharge differential. A pump will not cavitate as easily in a pressurized system but that is only due to the raised boiling point when a liquid is under positive pressure and cavitation is simply fluid boiling in the suction of a pump due to the lower pressure in the suction venturi.
 

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Actually...the thermastat opens and all the hot water comes out of the motor into the top of the radiator. The hot water runs down the radiator, cools off and returns (cool) into the block via the lower radiator hose. So the coolest part of an engine would be the water pump inlet. I think... Someone correct me if I am wrong....
I knew that I don't know what I was thinking. It's obvious that water doesn't get pulled in from the top.
 

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wskaiser said:
I will argue that point with you. The pressure in the system only assists the pump if the discharge of the pump is not at the same static system pressure.
In a closed system like a auto cooling system the pump will develop the same discharge differential pressure even if the system has no pressure or if it has 15 psi on the closed system. If the pump discharge pressure indicates 50 psi with no static pressure on the closed system the pump discharge pressure would indicate 65 psi with a 15 psi static system but the suction pressure would also be positive 15 psi leaving you with the same actual 50 psi discharge differential. A pump will not cavitate as easily in a pressurized system but that is only due to the raised boiling point when a liquid is under positive pressure and cavitation is simply fluid boiling in the suction of a pump due to the lower pressure in the suction venturi.
Yeah, that is a good point. I will agree with you there.:D
 

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I still like Kevin's suggestion from a LONG time ago.
Double check to make sure your fan in pulling air through the rad instead of trying to push it out the front. This will not be a problem when you are sitting still but will basically stop airflow once you get moving. Inadvertantly reversing the wires on an electric fan makes this an easy thing to do. I know an absolutely brilliant guy who did this once.

Make sure the system is properly burped. Like run for 15-20 minutes with the cap off and the heater running.

Pretty basic stuff but you'd be surprised how often it gets messed up.
 

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Mitch, how are you doing with the overheating problem? I saw some pictures and you're write up stating no improvement despite new upper and lower rad hoses and a high flow thermostat. They don't appear here now. Any other changes in store? Must be real frustrating trying to enjoy your ride with this problem hampering things. Do you have more info for us to ponder? Previous setup, engine, how many miles on this new engine, etc... Something that may help us, help you.
 

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Awesome thread guys!

I also have a hot running Nova. Interestingly it didn't used to be....actually it was, I fixed that and changed something else and it runs hot again.

The first time around it was airflow. Ran fine on the highway, 170-180, started getting hot in town. I ditched the flex fan the PO had installed for a stock five blade and thermo clutch set-up with the stock shroud. Problem solved, ran great in tow and on the road.

Next problem is obviously a flow issue. I swapped out the 2.56 rear gears for 4.10s. My crusing rpm jumped by about 1000 rpm to 3400 @ 60-65(hafta change the speedo gear still). Now the car runs hot on the highway, easily gets to 210. It never went above 180 before and the only change is the gears.

Before this thread I was thinking different pulleys, cavitation, or a water pump made for higher rpm use. Now I think I will pull the thermostat out in the morning and take it for a drive. I am guessing that could be the restriction point. Maybe the lower hose next, I'll make sure it has a wire in it.

I will say that without scientific background my first thought was cavitation since nothing changed except rpm. This could have a high flow pump on it too. Sounds like I might do better with a stock pump if I need to change it. Does a place like NAPA stock a high flow thermostat if I need one or will I have to mail order the bugger?
 

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Discussion Starter #48
Shane65

I'm just about out of ideas. I did order a new Mr. Gasket High flow thermostat from Summit yesterday. Looks just like the Robert Shaw thermsotat. The pictures I had did go away.. I'm at work and the firewall wont let me get to photobucket, So I will post later.

Mitch



Shane65 said:
Mitch, how are you doing with the overheating problem? I saw some pictures and you're write up stating no improvement despite new upper and lower rad hoses and a high flow thermostat. They don't appear here now. Any other changes in store? Must be real frustrating trying to enjoy your ride with this problem hampering things. Do you have more info for us to ponder? Previous setup, engine, how many miles on this new engine, etc... Something that may help us, help you.
 

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Mitchc said:
I have a 62 with a 383 and TPI, 350 turbo..
Mitch
Hey Mitch...I was wondering here if your 383 is based on the 400 block or the 350 block? If its the 400 block did you drill the heads for the steam holes? Just wondering is all...:)
 

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My car had one of those flow restrictors in place of the thermostat. I took it out and the car now runs cooler. Not as cool as it did when it was turning 2500 rpm on the road but at 180-190 on a hot day, it is much better than the 210 it was with that restrictor in place. I also have a bit of a lower hose issue created by the PO so once I get that fixed maybe I can shed another 5-10* off.
 

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Discussion Starter #53
Here are the pictures I posted last week.









As you can see what the gauge reads (left head) and what the ECM reads (intake)


I just finished putting the new Mr. Gasket high flow thermostat in .. i will report later.. or just drive it off the nearest bridge.. :)

Mitch
 

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What is the waterpump application for? Is it a reverse rotation for a serp belt, or the old V-belt, standard rotation?
 

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Discussion Starter #55
Its a 84 Chevroelt Pickup Heavy Duty. Autozone CWP-520HD

DrDenny's 69 Rat said:
What is the waterpump application for? Is it a reverse rotation for a serp belt, or the old V-belt, standard rotation?
 

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Ya, that would be something if they were going the wrong way. I did that on a S10 blazer I used to have, put a 4.3 in place of a 2.8, tried to use the old 2.8 fan...:eek:

Denis
 

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Discussion Starter #58
DrDenny's 69 Rat said:
Ya, that would be something if they were going the wrong way. I did that on a S10 blazer I used to have, put a 4.3 in place of a 2.8, tried to use the old 2.8 fan...:eek:

Denis
The fans are going the correct way.. I can put a rag in front of the grill and it will suck them to the grill..

Mitch

The car is still getting hotter than I want.. I'm just out of idea's.. I put the new thermostat in yesterday I got from Summit.. Mr. Gasket high flow.. Its not getting as hot but still up around 245...

I
 

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Can the Tech 1 be connected and the car driven at the same time? It would be nice to know the rpms and timing at the highway speeds that make it heat up. A knock sensor will retard the timing to protect the engine and if the knock sensor is faulty or picking up some type of vibes from the engine then this will contribute to overheating(IMO). With the Accel system the timing is retarded quite a lot to the point that you want the timing map not too close to detonation. Is this a freshly built engine?
 

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Discussion Starter #60
Shane65 said:
Can the Tech 1 be connected and the car driven at the same time? It would be nice to know the rpms and timing at the highway speeds that make it heat up. A knock sensor will retard the timing to protect the engine and if the knock sensor is faulty or picking up some type of vibes from the engine then this will contribute to overheating(IMO). With the Accel system the timing is retarded quite a lot to the point that you want the timing map not too close to detonation. Is this a freshly built engine?
Shane65

The Tech 1 can be connected and driven.. The knock sensor is new, which dont mean anything.. but It seems to work.. If I get some pinging it will retard the timing.. I have the int timing set at 10 degrees.. factory settings is 6 degrees.. at 6 degrees the engine seems so lazy, it gets real happy up around 12 but..

the engine was built this winter..

Mitch
 
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