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I swapped 4.10 gears into my Nova. It previously had 2.56's. The car runs cool at slow speeds,even in traffic, no problem. Once on the highway at 60-65 mph it starts getting hot and will get up around 210 degrees. If I slow down 10 mph the temp goes back down.

It sure seems like I am getting to a point where the pump is turning too fast and cavitating. Is there a different set of pulleys the factory used on cars with deep gears? Is there an aftermarket solution? The car had a restrictor in place of the thermostat, I removed it, and now it flows wide open. That made a slight improvement but didn't solve my problem.

Looking for ideas on how to cool down this hot Nova:eek:
 

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Maybe the engine working harder (with 4.10's) and not cavitation is why its running hotter. What radiator/fan/shroud are you eunning?
 

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Running hot at idle but not highway is an indication of insufficient air flow over the rad.
Running hot at highway speeds but no slow speeds is an indication on insufficient cooling. You may have a plugged rad row or two. It's also possible the belt is slipping.
 
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Discussion Starter #5
The car has a full factory type shroud and factory five blade fan and clutch. The fan clutch is brand new as well.

I can further check out the rad I guess but this was a V8 AC car to start with, the rad should be large enough especially since the condensor has been removed. I doubt there is a blockage but possible. Maybe it is time for a re-core.

I wonder what help it would be to refit a t-stat?

The reason I think the pump is cavitating is that backing off just a few hundred rpm makes all the difference. It is like you get to a line, if you cross it the car gets hot, if you don't it runs fine.

Nobody else has had this happen? The original question still stands, is there a different pulley set out there to slow the wp?
 

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The reason I think the pump is cavitating is that backing off just a few hundred rpm makes all the difference. It is like you get to a line, if you cross it the car gets hot, if you don't it runs fine.

Nobody else has had this happen?
Mine does the same thing on really hot 100 degree days. 60 mph on the highway and all is fine, 65-70 mph and it starts to climb up from 195 to 210. Drop back to 65 and in a mile temps drop back to 195. I would like to know what you figure out if you ever fix the problem.
 

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T

The reason I think the pump is cavitating is that backing off just a few hundred rpm makes all the difference. It is like you get to a line, if you cross it the car gets hot, if you don't it runs fine.

Nobody else has had this happen? The original question still stands, is there a different pulley set out there to slow the wp?
What rpm is this line? You never rev'd it to that rpm before the gear change? I'd check the simple things first. I'd say double the check the fan belt for glazing. I'm thinking it's slipping at a certain rpm when the fan load exceeds the belt friction. Don't assume it will squeal.
If you are convinced it's the water pump, there are aftermarket pumps out there.
Stewart and Edelbrock make good pumps
 

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Just a shot, but check the lower hose for collapsing. When the RPMs go up maybe the hose isn't supporting the demands of the water pump. I wouldn't worry about the water pump itself pumping too hard, it's always something else.

The lower hose sometimes has a spring inside of it to ensure it doesn't collapse. If it's getting a little old maybe the spring isn't doing it's job. Good luck!

Also double check Paul's suggestions. He's pretty much correct all the time.

Rod
 

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Nobody else has had this happen?
Ever since I've owned my Nova(many engine combos) it has a tendency to creep higher and higher with the rpm over 3500. Slowing down brings the temp down--2 row radiator, 3 row, radiator, 4 row, and my 2 row aluminum; clutch fan, flex fan, electric fan; iron pump, aluminum pump, and now my 3rd electric pump, whatever.....it has always done it. It never goes much over 200 after many miles of driving way too fast, but if I drive at 3000 or less it stays nice and cool. When I get back in traffic, it's just fine.

There are several different sized pulley combos; I'm sure you could find something out there.
 

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Discussion Starter #10
Well, At least I am not alone on this:beer:

The rpm point is right about 3400 rpm.

The belt looks good and is nice and tight.

I guess it really isn't that big of a deal. It doesn't go over 210 so I am not overheating it, and it does stabilize there on our typical 30 mile highway cruise. I would just prefer it ran a little cooler;)

Come to think of it my Buick will run warmer if I drive it faster too, not nearly as hot as the Nova gets but 190 instead of 175-180.

So with that under control....what are the pros/cons of installing a t-stat again? The car is a summer toy, it warms up fine on its own. Just curious.

Thanks guys for all of the input.
 

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If I read correctly you don't have a stat in the car. You must run either a stat or a flow restrictor so the water will not circulate too fast to actually be cooled by the radiator. With your 2.56s it probably didn't turn enough RPM at crusing speed to make the water flow too fast.
 

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Well, At least I am not alone on this:beer:

The rpm point is right about 3400 rpm.

The belt looks good and is nice and tight.

I guess it really isn't that big of a deal. It doesn't go over 210 so I am not overheating it, and it does stabilize there on our typical 30 mile highway cruise. I would just prefer it ran a little cooler;)

Come to think of it my Buick will run warmer if I drive it faster too, not nearly as hot as the Nova gets but 190 instead of 175-180.

So with that under control....what are the pros/cons of installing a t-stat again? The car is a summer toy, it warms up fine on its own. Just curious.

Thanks guys for all of the input.
Actually, the 210 temp on the highway is probably better. Engines are more fuel efficient when they run around that temp. At least newer ones are, I'm not sure if older ones are. You know, the ancient cylinder head designs and such, but it should still be the same for our older cars. And for what it's worth, if I go above like 2600 rpms, my car starts to heat up.

Matt
 

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okay so i have to ask 210 is not bad for engine 2 run? ive removed my thermostat and on the hot days here in georgia she will run 210 or a little better. it worried me for awhile considering my 350 blazer with thermostat runs 185-195 on the same days . so if i replace the thermostat on the nova should i expect it to run cooler? thanks, mark
 

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You must run either a stat or a flow restrictor so the water will not circulate too fast to actually be cooled by the radiator.
I've run every combo of thermostat, different sized restrictions, you name it--I don't use anything anymore. I never found any noticeable difference.
 

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Discussion Starter #15
If I read correctly you don't have a stat in the car. You must run either a stat or a flow restrictor so the water will not circulate too fast to actually be cooled by the radiator. With your 2.56s it probably didn't turn enough RPM at crusing speed to make the water flow too fast.
I ran it both ways already. It cools better without the restrictor. I think you have succumbed to an old wives tale. The water can not move too fast through the radiator. In fact, if you slow the flow, the water can spend too much time in the engine creating hot spots and steam pockets.
 

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I ran it both ways already. It cools better without the restrictor. I think you have succumbed to an old wives tale. The water can not move too fast through the radiator. In fact, if you slow the flow, the water can spend too much time in the engine creating hot spots and steam pockets.
Indeed.

Matt
 
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