DIY "Airlift" for Easy and Quick Coolant Change

I joined this forum back in 2007 but this is actually my first post.

I just bought my first Prius, a 2008 Touring with every goodie except leather. It's for my daughter but I'm loving the car and I may have to buy another for myself. After doing plenty of research here and elsewhere I've been doing preventative maintenance and the biggest worry I had was doing a proper bleed on the cooling system after a flush. I've been a BMW guy for years and bleeding those systems is a pain but nothing like what I read for the Gen 2 Prius.

I'd never heard of the Airlift vacuum and fill system until reading about it here a few days ago. I didn't want to spend money on yet another rarely used tool so I did rigged my own DIY vacuum fill on the coolant system. I used one of those spill-proof funnels for coolant system filling which I bought a few days ago from Amazon (EPAuto for only $22). I pulled a vacuum in the system with the funnel installed in the radiator by using about a foot of copper pipe inserted through a rubber stopper (cork), AC gauges, and a vacuum pump. I kid you not, after getting everything set up, it took me maybe 5 minutes to refill and bleed the system at which point I had good heat from the heater. I suspect over the next few days some trapped air will make it to the top of the radiator so I'll be checking for that.

Obviously this won't be easy for everyone because not everyone will have AC service equipment sitting around. I do only because I took an interest years ago and I've been repairing my own automotive AC systems ever since. I wrote this only to point out another way to overcome the coolant bleeding hassles.

If you check the pics you'll get the general idea. I should have taken more, maybe I'll reshoot the setup and post those pics later.

Anyway, the gist is:

1) Follow all the usual draining directions.

2) Install the spill proof funnel using the adapter that fits the radiator opening (the blue one in the EPAuto funnel kit). Firmly snug all the fittings so that a good seal is achieved.

3) Plug the bottom of the funnel with the copper pipe/rubber stopper.

4) Pull a vacuum in the system and CLOSE the AC gauge valves. Very important to close the valves, otherwise in the steps below coolant will be sucked into the AC gauges, not good.

(I have to admit I don't know how deep the vacuum can be safely taken to. Any decent AC vacuum pump will pull very low, like -29.9 in/Hg. I've got concerns about going too far because I've read that the rubber gaskets in the radiator end caps can be sucked in, resulting in a bad leak, obviously an undesired outcome. Venturi based vacuum pumps like the Airlift won't pull that low so I stopped at about 26 and, as quickly as I could, started the coolant flow back into the system.)

5) Fill the funnel with coolant.

6) Gently break the seal formed by the stopper in the bottom of the funnel. Don't completely remove the plug; use it to moderate the coolant flow. Completely removing the plug will quickly result in a whirlpool where air, instead of coolant, will be sucked in. Re-plug the funnel to stop the flow and top up coolant in the funnel as necessary.

7) When no more coolant will flow in, with plenty of coolant still in the funnel, pull the heater pump relay and use the “jumper method” to run the pump until no air bubbles are appearing in the funnel.

(I don’t know how long it’s safe to run the pump but I did approximately a 10 second on/10 second off cycle while monitoring the current, around 4 amps the whole time in my case. I didn’t count but I’d guess it took less than 10 cycles before no more bubbles were appearing in the funnel.)

8) Reinstall the relay.

9) Do whatever is necessary to get the ICE to start and with the heater on HI monitor the vents for heat.

(I did this with the engine completely cold and an outside temp of about 55 degrees F so with the heater on HI the ICE started. Within a minute or so I was feeling warm air from the vents. I didn’t have to do the inspection mode thing.)

10) Check the (cold) radiator coolant level over the next few days and top up as necessary.

Cheers,

Keith

 

I actually have two.

One is a serious kludge. I pulled the compressor from a dying old refrigerator on my Dad's farm about 25 years ago and rigged the necessary fittings, wiring, frame, and handle. It works OK but over the years got to where it would not pull a deep vacuum that is recommended for AC repair. I used it for this project just in case I screwed up and let coolant get into it.

The other is a slightly more fancy one that I bought at Harbor Freight.

 

Your venturi pump will work just fine. According to HF's website, their venturi vacuum pump is good for 28.3 in/Hg vacuum.

My point was that a good AC vacuum will pull a deeper vacuum and I was worried about potential damage to the cooling system. I watched a few Airlift YouTube videos and I recall 25 or 26 in/Hg being the vacuum that was obtained so I stopped at an indicated 26 on my gauge.