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I have an Airlift 50000 to use in flushing and refilling my cooling system.

I used it to flush the system with distilled water 3 times and then to fill with coolant after replacing the coolant expansion tank with a Radium. Each time the Airlift reached and held 25psi vacuum.

After driving the car my coolant temperature was erratic between 195 and 215 so it would seem I have an airlock. I thought the Airlift would eliminate this but I guess not.

I decided to drain the coolant and use the Airlift again to refill the system to remove the air lock.

I used the Airlift to draw the 25psi recommended vacuum. This vacuum was reached as before but now it bleeds down slowly as soon as the vacuum is drawn on the system.

I'd appreciate some advise on what my issue might be, what to check and what steps to take from any of you guys that have some experience with this.

Thanks

Mark
 

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I have tried everything under the sun, and time and repetition are the only things that have worked reliably. Granted, I also have the heater core bypass, so my cooling system is more complicated than stock, too.

That all being said, you don't mention bleed screws. Did you open the one by the radiator and the one by the engine block? If you didn't, there is your problem. If you did, make sure they aren't loose.
 

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Just my experience - I used an Airlift on my Caterham. I followed the instructions, did not exceed any pressures. It appeared to work great. However, it concaved both the top and bottom tanks of the radiator.
 

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If it now bleeds down slowly.... sounds like you have a leak somewhere. If you're really lucky its where you're attaching the airlift to the car.
 

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When I did the coolant replacement with my airlift, I found that it looked full but actually wasn't and still needed to be burped. I pull a vacuum three times and then run the burp procedure which if I remember right is to let it idle, keep refilling until the radiator fans kick on for a couple of minutes. < But check me on that because I'm going by memory.

@cyow5, The beauty of the airlift is that you don't need to use the bleed points. Out of curiosity, I did check them after I used the airlift and they sprouted water right away.

If you're not holding a vacuum, I agree with @jds62f, you have a leak but first make sure you've got a good seal with the airlift.
 

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When I did the coolant replacement with my airlift, I found that it looked full but actually wasn't and still needed to be burped. I pull a vacuum three times and then run the burp procedure which if I remember right is to let it idle, keep refilling until the radiator fans kick on for a couple of minutes. < But check me on that because I'm going by memory.

@cyow5, The beauty of the airlift is that you don't need to use the bleed points.
You mention having to burp which absolutely does use the bleed points. The whole point of the airlift is to avoid having to burp, and, since I always end up burping, I just do that from the start. The airlift poses a significant risk since you are pulling on seals and parts designed to only be pushed on, so the duplicated effort tells me it is not worth the risk at all.
 

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You mention having to burp which absolutely does use the bleed points. The whole point of the airlift is to avoid having to burp, and, since I always end up burping, I just do that from the start. The airlift poses a significant risk since you are pulling on seals and parts designed to only be pushed on, so the duplicated effort tells me it is not worth the risk at all.
The airlift fills the system beyond the level of the bleed ports. As I said, they spring water as soon as you open them. Please correct me if I'm wrong because, again, I'm going by memory, but the bleed screws are part of the fill procedure but they are closed when operating the engine during the burp procedure.

The airlift indeed does collapse the rubber lines in the system, if they are cracked or marginal this will accelerate their failure. But a healthy set of hoses will not experience damage from pulling a vacuum on the system and exercising the hoses to expose a weak one may not be such a bad idea.

To each their own on what their favorite method is but I don't believe that pulling a vacuum on a healthy system will cause issues.
 

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The airlift fills the system beyond the level of the bleed ports. As I said, they spring water as soon as you open them. Please correct me if I'm wrong because, again, I'm going by memory, but the bleed screws are part of the fill procedure but they are closed when operating the engine during the burp procedure.

The airlift indeed does collapse the rubber lines in the system, if they are cracked or marginal this will accelerate their failure. But a healthy set of hoses will not experience damage from pulling a vacuum on the system and exercising the hoses to expose a weak one may not be such a bad idea.

To each their own on what their favorite method is but I don't believe that pulling a vacuum on a healthy system will cause issues.
I'm not worried about the rubber tubing so much as the radiator and seals. Under pressure, the radiator is trying to stretch (tension); under vacuum it is trying to collapse (compression). This can lead to buckling very easily of some of the large, flat, unsupported areas, but not guaranteed. The other issue is how the seals are designed, especially around the end caps. Under pressure, the seal is squeezed in a way that increases its effectiveness. Under vacuum, this principle is reduced and reduces the effectiveness. Again, whether or not it is enough to induce failure varies, but it is undeniably a step in a bad direction.

Regarding the bleed screws, burping is a synonym of bleeding, so I thought they were used. I certainly use them since, even if they gush water at first, sometimes they still help, especially if an air bubble moves towards them.
 

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Thanks for the great discussion.

I'm not worried about the rubber tubing so much as the radiator and seals. Under pressure, the radiator is trying to stretch (tension); under vacuum it is trying to collapse (compression). This can lead to buckling very easily of some of the large, flat, unsupported areas, but not guaranteed.
The parts of the radiator that are seeing coolant are the end tanks and oval tubes. I agree that these are stronger under positive pressure than negative, but from what I can tell, there's enough safety factor built into the materials that the 10PSI or so that the airlift can draw isn't enough to cause any collapsing.

The other issue is how the seals are designed, especially around the end caps. Under pressure, the seal is squeezed in a way that increases its effectiveness. Under vacuum, this principle is reduced and reduces the effectiveness. Again, whether or not it is enough to induce failure varies, but it is undeniably a step in a bad direction.
The only seal that I can think of that isn't soldered, brazed, or welded is the one between the end tanks and the heat exchanger. In the radiators I've seen apart, the gasket sits in a groove in the HX section and is held down by the end cap. This design appears doesn't depend on positive pressure to make the seal, it appears to only depend on the compression of the end tank against the gasket. This video is a decent example of the construction. Skip to 3:30 for the gasket.


Regarding the bleed screws, burping is a synonym of bleeding, so I thought they were used. I certainly use them since, even if they gush water at first, sometimes they still help, especially if an air bubble moves towards them.
I suppose that I used the the two different terms to separate the process of fluid fill without the engine running vs the second step of running the engine to eliminate air bubbles. But my point is that the bubbles in the lines at the bleed points are eliminated using the airlift so using those points is not necessary, it is just not able to get the last bit of coolant into the system for reasons that I don't understand. Clearly there is another bubble in the system somewhere that needs to be cleared.
 

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For what it’s worth, I bought an Airlift for my recent radiator replacement after hearing about how difficult the process is and couldn’t get it to hold a vacuum. I feared that I had a leak somewhere, but ended up filling and burping the traditional way and it’s been trouble free since. Maybe I just didn’t have a good seal on the Airlift, but I don’t think I’ll try it again during my next flush.
 

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Stick a Dorman vacuum cap on the bleed port of the Radium (sticks out of the fill neck). You (like I did) may not have a good seal with the Airlift adapter inside the fill neck.
 

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Used it twice and never a problem. What I do that I noticed that no one ever mentions is that I raise the rear on some ramps making the radiator the lowest point in the system.
 

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Discussion Starter #14
Stick a Dorman vacuum cap on the bleed port of the Radium (sticks out of the fill neck). You (like I did) may not have a good seal with the Airlift adapter inside the fill neck.
Which Airlift adapter did you use to put into the Radium?
 

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With the airlift I was able to drain and refill about a dozen times in a single day. It was a life saver in that regard, as I found it tiresome getting all the old coolant out of the system in changing over to toyota red. Now that the car is 10+ years old I do worry a little bit that it will kill a hose, and I have no desire to chase a coolant leak.
 

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With the airlift I was able to drain and refill about a dozen times in a single day. It was a life saver in that regard, as I found it tiresome getting all the old coolant out of the system in changing over to toyota red. Now that the car is 10+ years old I do worry a little bit that it will kill a hose, and I have no desire to chase a coolant leak.
I love it too. Did you find that you still had to burp the car as I did?
 

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I love it too. Did you find that you still had to burp the car as I did?
I did no burping. Drove it around a bit and topped it off once.
 
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