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Why isn't air bleeding necessary on automotive radiators?

1K views 38 replies 20 participants last post by  8051 
#1 ·
I've drained & back-flushed automotive radiators and heater cores many times on my various vehicles. When I refilled the cooling system w/coolant and H2O I never had to perform any steps to bleed air out of the system though -- just top off the overflow bottle. Why is it necessary to bleed air out of a computer liquid cooling system?
 
#2 ·
Air in loop can go by pump and kill it. befor that reduce the flow over gpu block /cpu or in rad. Makeing the water loop not worth it if not bleed right . MAkeing a loop run @ 75% not 99% is 10-15 % in temps. also the sound in loop as water pass over air pockits makes a noise. Most in water loops want low DB noise and temps.

OK then why a turbo with out a intercooloer. ? Needs to be cool for the POWER.

Btw yes cars have auto bleeder. just need refilling. like water-loops for pc just more often@the start loop size vs car. cant let the pump run dry. CAr vs pc same size the rez in car would be a cup not the 1/2 gallon.
 
#3 ·
Every car engine I ever flushed and replaced the coolant in had to be bled of air. After the initial refill of coolant, I had to run the engine and keep adding coolant until most of the air pockets had worked their way out. Even then, I usually had to add some more coolant after a few days of driving since more air would be worked out of the system. However, automotive cooling systems are usually better designed than computer cooling systems.

A properly designed computer cooling system will have fewer places to trap air, making bleeding easier. The reservoir and fill port should be at the highest points of a loop to help avoid air pockets but that rarely is done or is even practical. Top mounted radiators with the inlet and outlet ports pointing down create a huge air pocket but mounting them with the ports pointing up and still below the reservoir just isn't going to happen. Even vertically mounted radiators usually have the ports at the bottom, again creating a huge air pocket. Water blocks usually have air pockets because of the way they are designed with ports on a face rather than at the tops and bottoms of the blocks.
 
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#4 ·
Quote:
Originally Posted by Lady Fitzgerald View Post

Every car engine I ever flushed and replaced the coolant in had to be bled of air. After the initial refill of coolant, I had to run the engine and keep adding coolant until most of the air pockets had worked their way out. Even then, I usually had to add some more coolant after a few days of driving since more air would be worked out of the system. However, automotive cooling systems are usually better designed than computer cooling systems.

A properly designed computer cooling system will have fewer places to trap air, making bleeding easier. The reservoir and fill port should be at the highest points of a loop to help avoid air pockets but that rarely is done or is even practical. Top mounted radiators with the inlet and outlet ports pointing down create a huge air pocket but mounting them with the ports pointing up and still below the reservoir just isn't going to happen. Even vertically mounted radiators usually have the ports at the bottom, again creating a huge air pocket. Water blocks usually have air pockets because of the way they are designed with ports on a face rather than at the tops and bottoms of the blocks.
Purging the liquid cooling system of air on computers sounds like a nightmare.

For my vehicles I usually just ran the engine for 5 minutes or so and topped off the overflow container -- then checked the overflow container a couple times over the next week. I imagine the much more powerful water pump in my vehicles contributes to swiftly purging it of air as well.
 
#5 ·
Air in car radiator systems is just as real a concern as it is in PC watercooling. I think it just tends to work its way out easier because of the volume of water being moved and the size of the passages.
 
#6 ·
As mentioned above, your vehicle's coolant reservoir tends to be much higher placed in a vehicle than the radiator/s and components needing cooling. Additionally, because vehicles require coolant, their incorporation by manufacturers tends to be more critically designed for ease-of-servicing.
 
#8 ·
On many vehicles there are bleeder valves you should open to purge air out of the cooling system. In fact, you find them on pretty much every VW, Audi, BMW, Porsche, Mercedes, Ford, Chevy, etc out there. Just because you didn't use it doesn't mean it wasn't there and thus ignored.
 
#9 ·
Quote:
Originally Posted by 8051 View Post

This whole thread makes me like AIO or hybrid coolers that much more.
A properly designed loop shouldn't take more than a few minutes to bleed. Even if you don't get all the air out, it will eventually make its way to the reservoir so just top it off as needed (like topping off the expansion tank in the cars you have done). That shouldn't be too difficult for you.
 
#10 ·
Then you have the technicians that use the vac fill method. They have vac pumps for putting the system in a vac just like an AC system and then filling it so you have no air pockets at all.
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#11 ·
Mostly because the cooling loops have been designed by people with half a brain so they are for the most part self-bleeding.

I mean, look at my computer. I have a big frickin' radiator right on top of the case and the ports facing downwards - of course it takes ages to bleed.
 
#12 ·
Quote:
Originally Posted by Andrew LB View Post

On many vehicles there are bleeder valves you should open to purge air out of the cooling system. In fact, you find them on pretty much every VW, Audi, BMW, Porsche, Mercedes, Ford, Chevy, etc out there. Just because you didn't use it doesn't mean it wasn't there and thus ignored.
Where is this "bleeder valve" on Fords located? It's not on the radiator, it's not in the expansion tank so where is it?
 
#13 ·
8051: Depends on the model and what year you are talking about. Some cars has the bleeder around the thermostat housing or somewhere high in the water loop. Watch for a brass screw since that is what manufacturers normaly use. On several cars like BMW there is an "easy" way to see if you have gotten the air out and that is to run the engine temps up, turn the heater on in your car.
If it blows out cold air or just alittle hot then its a good sign you have air trapped inside. But alot of BMW cars has the bleeder valve at the heater radiator. Can be a pain in the ass to get to it
sozo.gif


Another way to "bleed" the car is ofc to try and place or tilt your car so the point at where you fill the water in is the highest point. Start the car and let it idle until the thermostat open and water starts rushing into the system. Refill and find the lowest thick watertube on your radiator and press it with you hand hard. And just keep pumping it. If that does not help, you need to find the bleeder valve.

Hang on... Overclock.net..... computers.... what the h... now we are on cars! what happend!!
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#15 ·
Quote:
Originally Posted by Cooked CPU View Post

8051: Depends on the model and what year you are talking about. Some cars has the bleeder around the thermostat housing or somewhere high in the water loop. Watch for a brass screw since that is what manufacturers normaly use. On several cars like BMW there is an "easy" way to see if you have gotten the air out and that is to run the engine temps up, turn the heater on in your car.
If it blows out cold air or just alittle hot then its a good sign you have air trapped inside. But alot of BMW cars has the bleeder valve at the heater radiator. Can be a pain in the ass to get to it
sozo.gif


Another way to "bleed" the car is ofc to try and place or tilt your car so the point at where you fill the water in is the highest point. Start the car and let it idle until the thermostat open and water starts rushing into the system. Refill and find the lowest thick watertube on your radiator and press it with you hand hard. And just keep pumping it. If that does not help, you need to find the bleeder valve.

Hang on... Overclock.net..... computers.... what the h... now we are on cars! what happend!!
drunken.gif
offtopic.gif
I've never seen such a thing as a "bleeder valve" on any of the Fords I've ever owned -- or my Jeep Cherokee.
 
#16 ·
Depends on the car.

On the Gen2 SBC, the LT1, there are multiple bleeder screws and due to reverse flow cooling are notoriously difficult to bleed. The waterpump cools the cylinder heads before the block, and its easy to get air trapped in the system.
 
#17 ·
Yes many newer cars have bleeder valves, this has been around since the car manufactures designed reverse flow cooling systems. Since pushing the coolant down from the heads is for one better cooling but the side effects are air locks hence why they now have bleeders valves..

As said already cars are using a larger loop so a small amount of air in the system really won't be noticed also they are open to vent air through the over flow, most PC water cooling systems are sealed to prevent leaks and spillage. PCs also have a lot of smaller tighter places for air to get trapped.

But a properly and not overly complex system. (lots of blocks and tubing) should be real easy to get air out of..
 
#18 ·
If you bleed automotive vehicles you should then know that it depends on the highest point in the vehicle. In my vehicle the overflow tank is the highest so i do not need to bleed. But some cars it is not the highest point which means they must unscrew the bleeder valve on the thermostat.
 
#20 ·
Quote:
Originally Posted by Cooked CPU View Post

Most fords often dont have bleeder valves cause imo they are to cheap to do so sadly... You normaly have to "burp" fords... And there is a difference on some models depending if you have an US or EU model.
Not true, it's just they use the overflow tank. I own the Australian Ford Falcon XR6. Not having a bleeder valve is a very poor way to call a company out. They literally self bleed which is BETTER for the end user.
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#21 ·
Well reason I call the company out is because I dont have a clue about cars in australia but here in norway. Take the Ford mondeo 2012 model with the 2.L engine. One would think the highest point is the overflow tank.
But no, its located on the heater radiator and the real f... up part is that you have to go under the dashboard and bleed it so without a hose or something to catch the water when it comes, you get it inside the car... Yea.. great... But I do know there same car is very different from continent to continent.
 
#22 ·
Quote:
Originally Posted by Cooked CPU View Post

Well reason I call the company out is because I dont have a clue about cars in australia but here in norway. Take the Ford mondeo 2012 model with the 2.L engine. One would think the highest point is the overflow tank.
But no, its located on the heater radiator and the real f... up part is that you have to go under the dashboard and bleed it so without a hose or something to catch the water when it comes, you get it inside the car... Yea.. great... But I do know there same car is very different from continent to continent.
Wow, yeah i just searched that up! That's amazingly stupid! LOL
 
#26 ·
Quote:
Originally Posted by 8051 View Post

This whole thread makes me like AIO or hybrid coolers that much more.
Joke's on you. AIO coolers aren't properly bled before being sealed. They have the same giant air bubbles as unbled systems, but with no way of actually fixing the problem sans breaking the thing open and defeating the whole point of an AIO. Furthermore, since evaporation still happens but they lack a reservoir, that air bubble actually gets larger and more disruptive over time vs custom loops which self-correct.
 
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