Cooling Bigger Engines

[BRX]

I would like to see how others are dealing with the additional heat their bigger engines produce.


In my case, I have a 5.7L Toyota V8 paired to the Jackson Racing Dual Oil Cooler and Radiator. JDL Fan shroud and 2 10" pushing fans on the condenser. Weather here is almost always above 90 and is usually about a 100 degrees.


Haven't actually been able to beat down on my car after the swap due to the clutch slipping (Waiting on my dual clutch). But from the 2000 miles I drove it so far, it seems to run hotter than it should. With the stock 200F thermostat it would run 205-210 on the highway. Without any thermostat its slightly better but not by much at about 205 most of the time.


Slowing down actually reduces temps surprisingly but stays around the 195 mark without a thermostat.


Usually, these engines run cold and throw a code running without a thermostat at about 155 degrees. So my cooling system is extremely inefficient compared to the huge truck radiator (no surprise here).


I have a few theories as why it is that way:


1. Bleeding the coolant is a pain now and there is probably an air bubble trapped somewhere. I'm planning to elevate where I refill my coolant to solve this.


2. My mesh grill from Grillcraft is dramatically reducing airflow. I'll remove it and test my theory.


3. The JDL fans are inefficient. Might go back to the stock fans.


4. I doubt this is the issue, but without a thermostat I might not be giving the coolant time to exchange heat. I'll be installing a 175 degree thermostat to eliminate this theory.


Anyone else having heat issues with their swapped V8?

[Zer0]

Could have cavitation in the pump at higher rpm, or to high of flow for proper heat exchange with the smaller radiator. You could try slowing down the water pump speed with a different size pully.

[ILLSMOQ]

You had a 200 degree thermostat and it ran about 205-210? Are you looking at a scanner or data logger to see what the exact temp is or just looking at the gauge? Was it stable/steady the whole time?(you said you can’t push it hard so I guess you can’t really say)

Running no thermostat isn’t a good idea because as you mentioned the coolant never has a chance to sit in the radiator to actually cool down.

Try the cooler Thermostat like you said and see what that does. If that doesn’t drop your temp down then yes I’d say you need to look at a redesign to your cooling system.

You have factory fans behind the radiator or no? Just the two fans you mentioned up front?

[Ultramaroon]

Originally Posted by ILLSMOQ

Running no thermostat isn’t a good idea because as you mentioned the coolant never has a chance to sit in the radiator to actually cool down.

This makes no sense.

OP, are you boiling off any coolant? Do you have a decent expansion tank?

I'm liking your air bubble theory. Can you install a burp valve at some high point?

[ls1ac]

You could try a vacuum pump on the radiator to help move the trapped bubble out of the engine. We use this on our LS engines to help speed up the coolant fill proses.

[ILLSMOQ]

Originally Posted by Ultramaroon

This makes no sense.

OP, are you boiling off any coolant? Do you have a decent expansion tank?

I'm liking your air bubble theory. Can you install a burp valve at some high point?

What doesn’t make sense?

[Ultramaroon]

Originally Posted by ILLSMOQ

What doesn’t make sense?

Your statement that I quoted. Of course a thermostat is necessary but not for the reason you gave. It makes no sense.

[ILLSMOQ]

Originally Posted by Ultramaroon

Your statement that I quoted. Of course a thermostat is necessary but not for the reason you gave. It makes no sense.

Oh okay. I’ll leave it to you then.

[humfrz]

Originally Posted by BRX

I would like to see how others are dealing with the additional heat their bigger engines produce.


In my case, I have a 5.7L Toyota V8 paired to the Jackson Racing Dual Oil Cooler and Radiator. JDL Fan shroud and 2 10" pushing fans on the condenser. Weather here is almost always above 90 and is usually about a 100 degrees.


Haven't actually been able to beat down on my car after the swap due to the clutch slipping (Waiting on my dual clutch). But from the 2000 miles I drove it so far, it seems to run hotter than it should. With the stock 200F thermostat it would run 205-210 on the highway. Without any thermostat its slightly better but not by much at about 205 most of the time.


Slowing down actually reduces temps surprisingly but stays around the 195 mark without a thermostat.


Usually, these engines run cold and throw a code running without a thermostat at about 155 degrees. So my cooling system is extremely inefficient compared to the huge truck radiator (no surprise here).


I have a few theories as why it is that way:


1. Bleeding the coolant is a pain now and there is probably an air bubble trapped somewhere. I'm planning to elevate where I refill my coolant to solve this.


2. My mesh grill from Grillcraft is dramatically reducing airflow. I'll remove it and test my theory.


3. The JDL fans are inefficient. Might go back to the stock fans.


4. I doubt this is the issue, but without a thermostat I might not be giving the coolant time to exchange heat. I'll be installing a 175 degree thermostat to eliminate this theory.


Anyone else having heat issues with their swapped V8?

Do you feel that that temperature range is too hot .....?? If so, why ...??

You are running with antifreeze ....??


humfrz

[BRX]

Originally Posted by ILLSMOQ

You had a 200 degree thermostat and it ran about 205-210? Are you looking at a scanner or data logger to see what the exact temp is or just looking at the gauge? Was it stable/steady the whole time?(you said you can’t push it hard so I guess you can’t really say)

Running no thermostat isn’t a good idea because as you mentioned the coolant never has a chance to sit in the radiator to actually cool down.

Try the cooler Thermostat like you said and see what that does. If that doesn’t drop your temp down then yes I’d say you need to look at a redesign to your cooling system.

You have factory fans behind the radiator or no? Just the two fans you mentioned up front?

I'm looking at an OBD2 scanner and temps would keep rising while driving and cool down when I let off the throttle.

I will run a cooler thermostat, might make a difference since it is a smaller cooling system but I don't suspect it's the main issue. As I mentioned in my OP (at least in stock form in the truck) running no thermostat will cause the engine to never warm up with temps at about 155.

I have 4 fans in total. 2 10" pushing fans in the front and 2 JDL fans with their shroud. I will go back to stock if I have the space. The OEM fans flow much more air.

Originally Posted by Ultramaroon

OP, are you boiling off any coolant? Do you have a decent expansion tank?

I'm liking your air bubble theory. Can you install a burp valve at some high point?

Not boiling anything at the moment but the weather is getting warmer and I suspect I will with the new clutch.

I have the Perrin expansion tank and it works as it should.

I have a valve installed but with the stock location filler cap I can't be sure there are no air bubbles. I will delete the stock filler cap and weld one on the water jacket coming off the water pump to be at the highest point possible when refilling.

Originally Posted by Zer0

Could have cavitation in the pump at higher rpm, or to high of flow for proper heat exchange with the smaller radiator. You could try slowing down the water pump speed with a different size pully.

This might be my last option as it's unlikely to happen, at least with a thermostat installed.

Originally Posted by humfrz

Do you feel that that temperature range is too hot .....?? If so, why ...??

You are running with antifreeze ....??


humfrz

This engine is designed to run at exactly 200 degrees. My stock truck with the same engine stays at that temp always and never goes above not even by 1 degree. I'm not saying it's dangerously hot but for driving like a grandma and still getting these temps it's definitely bothering me.

Yes, I'm running Toyota antifreeze (the pink one).

Sent from my Pixel 2 XL using Tapatalk

[humfrz]

Originally Posted by BRX

..................
This engine is designed to run at exactly 200 degrees. My stock truck with the same engine stays at that temp always and never goes above not even by 1 degree. I'm not saying it's dangerously hot but for driving like a grandma and still getting these temps it's definitely bothering me.

Yes, I'm running Toyota antifreeze (the pink one).

Sent from my Pixel 2 XL using Tapatalk

Well, hmmmm ......I don't understand how an engine can be designed to run at exactly any set temperature ..... It would seem to me that their are too many variables involved for that to be possible.

It appears your comparing the same type of engine in your truck, with it's cooling system, to the cooling system in your car ...... and expecting the exact same results. That may be unrealistic.

Unless the maximum coolant temperatures exceed 220 degrees F for any extended length of time ...... I wouldn't worry about it ......

humfrz - jest don't worry about too much no more.

[BRX]

Originally Posted by humfrz

Well, hmmmm ......I don't understand how an engine can be designed to run at exactly any set temperature ..... It would seem to me that their are too many variables involved for that to be possible.

It appears your comparing the same type of engine in your truck, with it's cooling system, to the cooling system in your car ...... and expecting the exact same results. That may be unrealistic.

Unless the maximum coolant temperatures exceed 220 degrees F for any extended length of time ...... I wouldn't worry about it ......

humfrz - jest don't worry about too much no more.

Using the 200F thermostat lol. And yes, that's what I'm comparing it to since it's the same engine. I don't want to run it 10 degrees hotter than it was designed to.

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[EAGLE5]

Originally Posted by Ultramaroon

This makes no sense.

I know, right? WTF?

If testing without a thermostat, you might want to instead just pin it open somehow to keep the back pressure up and avoid cavitation in the pump. But yeah, running without a thermostat is bad. Better yet, just buy a 180F thermostat.

Set up a water spray on the radiators to dump more heat.

Add more radiator.

Fender vents? Hood vents?

[BRX]

Originally Posted by jsimon7777

I know, right? WTF?

If testing without a thermostat, you might want to instead just pin it open somehow to keep the back pressure up and avoid cavitation in the pump. But yeah, running without a thermostat is bad. Better yet, just buy a 180F thermostat.

Set up a water spray on the radiators to dump more heat.

Add more radiator.

Fender vents? Hood vents?

Would this work? I can feel the heat on the windshield driving 50 mph... lol

Water spray is not a bad idea either. A friend has it setup to spray water on the radiator same time his water/meth kicks in.

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