A little background. Car was overheating pretty bad found out it was a collapsing lower rad. hose. Changed to new hose with spring. Now car slowly climbs in temp on the factory gauge and maintains 240 degrees but when factory gauge reads 240 an aftermarket gauge with sender in water outlet reads only 210. Engine bay feels really hot but have only worked on newer 4 cyl. cars so dont know if that is normal on older v-8s. any one have any suggestions on what might be going on. Also as of right now there is no thermostat in the car. Should i put the aftermarket in the head and see what that reads or do I have some other problem going on.

thanks
geo

 

Hi g,
Not a lot of information for a cooling system question.
What are the:
Year of car?
Engine?
Radiator?
Shroud?
Fan?
Fan clutch?
Water pump?
Radiator seals?
Shroud seals?
Help!
Regards,
Alan

 

What year? Did you change sensor? Aftermarket replacements are known to not be accurate with factory gauge.

 

yes sorry lol hard to evaluate with no real info. the car is a 78 new motor nothing fancy just mild cam, intake etc. new stock radiator with electric fans no shroud. everything on the motor is new. It has the stock 78 manifolds would this create extra heat as they might not flow enough?

thanks for any help

Geo

 

YES put the thermostat back in. It has been proven over and over that removing the thermostat is a big mistake and hurts cooling.

 

A thermostat doesnt help or hurt cooling it gets the engine up to that temp faster and if the cooling system is up to par keeps the engine at least at that temp,

 

no thermostat is the same as having a low temp thermosstat. Put in a 180* thermostat and drive it to get a feel for the cooling. You need airflow to cool it and it will heat up just sitting in your driveway. If its stable at 210* sitting there its on par with mine. drive it and the temp should come down prettty quickly. The engine bay does get hot pretty quickly, think of it as having 2, 4 cylinder motors in there.

 

see if you can borrow an infrared temperature gun,that will tell you your true temp.Try bumping up the timing as retarded timing will will cause it to run hot. A new engine might run a little hotter till it breaks in.

 

I think you should have one, my 74 was night or day depending on the shroud

 

 

How would I use the shroud with the electric fans. I have an infered temp guage and the manifolds are 650-750 degrees. The temp outside the manifolds like the plug wires, intake and such is showing 300 degrees. The stock guage is showing 240 from the head and the aftermarket gauge on the water outlet shows 210.

 

to do it correctly you mount the fans on a shroud and mount to the radiator, then the other ways are position the fans to allow the shroud to fit around the fans or get a different fan sized to fit factory shroud in place of clutch fan and make mounts to hold it there.

 

FOR WHAT THIS IS WORTH:

This information was obtained though years of doing this stuff and also having an in depth conversion with one of the major radiator manufactures.

Thermostats have a purpose and what they do is mainly restrict some of the coolant flow so that the coolant says in the radiator longer so it can be cooled. Here is a perfect example to those who pay attention when they work on their car.

Yes..I know there are people who do not run thermostats and swear by them and I guess that is good for them. Not me...the engine will have a thermostat or a large washer with a hole in it so slow down the coolant flow like are used on some engines for specific usages.



The heater hose fitting that is in your intake manifold is REDUCED to slow down coolant flow....to slow down the water flow to the heater core so it works better. IF you think I am full of it...change it out with a fitting that flows the maximum and see how well you heater works. And I am sure ...for many they may not be able to tell a difference. By having teh reduced fitting it is slowing down the coolant so you can get the heat to come off the heater core....thus...the radiator is the same way. IF you stop and think about it. Or...do as you wish and I guess all is good.

Coolant flow is also very important AT IDLE. Water pump impeller design and pulley size can effect this.

Making sure you have the front air dam is very helpful along with ALL foam seals that seal the radiator to the radiator support and the underside of the hood.

A good photos of your two electric fans would be nice if possible.

And I agree that I just do not trust temp senders any more and when I have a new engine I install my racing temp gauge that I know is correct and verify all is good and them put in or connect whatever the customer has or wants and make sure it is correct also.

I seriously doubt your cast iron exhaust manifolds are causing a problem due to there are countless of them on the road and this problem is not occurring....assuming that they are sealed up and not leaking.

DUB

 

You do realize the longer the coolant is in the radiator cooling, the longer it is in the engine heating.

 

Common myths and misconceptions about stats and coolant flowing too fast,

From Stewart, a top and trusted name in cooling,
Stewart Components is an industry leader in high performance automotive cooling system research and development. For the past 25+ years,

"Thermostats & Restrictors
We strongly recommend NEVER using a restrictor: they decrease coolant flow and ultimately inhibit cooling.

For applications requiring a thermostat to keep the engine at operating temperature, we recommend using a Stewart/Robertshaw high flow thermostat. This thermostat does not restrict flow when open. The Stewart/ Robertshaw thermostat enhances the performance of the cooling system, using any style of water pump. However, the Stewart Stage 1 high-flow water pump may require this thermostat to operate properly, and Stewart Stage 2, 3, and 4 water pumps simply will NOT operate with a regular thermostat because these pumps have no internal bypasses.

Stewart further modifies its thermostat by machining three 3/16" bypass holes directly in the poppet valve, which allows some coolant to bypass the thermostat even when closed. This modification does result in the engine taking slightly longer to reach operating temperature in cold weather, but it allows the thermostat to function properly when using a high flow water pump at high engine RPM.

A common misconception is that if coolant flows too quickly through the system, that it will not have time to cool properly. However the cooling system is a closed loop, so if you are keeping the coolant in the radiator longer to allow it to cool, you are also allowing it to stay in the engine longer, which increases coolant temperatures. Coolant in the engine will actually boil away from critical heat areas within the cooling system if not forced through the cooling system at a sufficiently high velocity. This situation is a common cause of so-called "hot spots", which can lead to failures.

Years ago, cars used low pressure radiator caps with upright-style radiators. At high RPM, the water pump pressure would overcome the radiator cap's rating and force coolant out, resulting in an overheated engine. Many enthusiasts mistakenly believed that these situations were caused because the coolant was flowing through the radiator so quickly, that it did not have time to cool. Using restrictors or slowing water pump speed prevented the coolant from being forced out, and allowed the engine to run cooler. However, cars built in the past thirty years have used cross flow radiators that position the radiator cap on the low pressure (suction) side of the system. This type of system does not subject the radiator cap to pressure from the water pump, so it benefits from maximizing coolant flow, not restricting it."

Im gonna believe stewart on this one,
I have discussed this with fellows who have earned a living in fields related to thermo hydro dynamics and I accept Stewarts tech, if you dont,
I highly recommend if you disagree with stewart, hit them an email or phone call, im sure you can set them straight. That they are wrong and your opinion is the only right one....

http://stewartcomponents.com/index.p...ormation_id=11

 

Are you doing this testing at idle?

If yes, what happens when you drive it faster then about 35-40 mph?

And yes, that coolant must flow slowly to cool theory is wrong. If it was true, then it would also be true that slower airflow though the radiator would absorb more heat from the radiator. But, we all know what happens without enough airflow....

Divide the coolant into individual cups of water and think what happens when a cup of water makes the loop through the coolant system.

Say one cup of water spends 2 minutes in the engine. It's temperature will increase, likely a fair bit. It could be 120* hotter coming out then going in. So, this cup of water then spends 2 minutes in the rad and cools by 120*. The net result is a constant average coolant temperature so all is well, right?

No, you don't want the coolant temperature swinging very much as it makes the loop. You want that cup of water to spend 10 seconds in the engine so it's temperature rises by 10* and then spend 10 seconds in the radiator so it cools by 10*. This keeps the coolant temperature more consistent so the block isn't cold while the heads are overheating.

 

 

HMMMM...thanks bats and others for the
information...something to consider. Hard for me to dispute teh performance of the cooling systems on the countless cars that are working fine that seem to contradict what Stewart states.

DUB

 

the fans have the correct rotation. ??

 

Youre welcome dub, its all good,


Back to the ops problem,

Assuming no air trapped in system,
Im gonna toss my guess on the fans not moving enough cfm because even a stock radiator being new should cool this set up,

Almost all aftermarket electric fans have a shroud, some are just made in the housing others are basically a simple ring around the blades,


Sometimes people will mount 2 like this,
The draw back is these waste a lot of radiator core,
The air flow is pretty much limited to a donut shaped area right under the blades,

If a person has a big overkill aftermarket radiator they might be okay but marginal or not cool in other situations,

Ideally we want to cover as much core as we can like this style,


The built in shroud covers far more core and cools better but all this is moot if the fans do not move enough cfm and most all the top fan manufacturers say a v8 needs at least 3200 to 3800, depending on who you ask, but this is a case more is better too little wont work,

Ebay sells a lot of crap fans with high rated cfm that is not correct.

After speeds are reached the electric fan should not be needed.




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